WO2014008899A1

WO2014008899A1 - A warning system for alerting drivers of vehicles

Info

Publication number: WO2014008899A1
Application number: PCT/DK2013/050228
Authority: WO
Inventors: Ole Mørk Lauridsen
Original assignee: Warning Systems Aps
Priority date: 2012-07-13
Filing date: 2013-07-05
Publication date: 2014-01-16
Also published as: EP2685439A1; EP2873067A1

Abstract

A method, system and arrangement of warning drivers of vehicles (1), said method comprising: transmitting a traffic bulletin signal (2) at a first predefined radio channel (PI) to one or more radio receivers (3) of said vehicles (1), which one or more radio receivers (3) comprise a Radio Data System facility, and transmitting at least one further radio signal being an interception radio signal (4, 4_1, 4_2, 4 n), wherein said interception radio signal (4, 4 _1, 4_2, 4_n) comprises information (25) in the Radio Data System frequency range of a second radio channel (P2) being different from the first radio channel (P 1), wherein said information is different from information in the Radio Data System frequency range of a third radio signal (5) transmitted from an external broadcasting station (6) at said second radio channel (P2), and wherein said information is configured so as to manipulate said radio receivers (3) to automatically tune said radio receivers (3) to said first radio channel (PI) to receive said traffic bulletin signal (2).

Description

A WARNING SYSTEM FOR ALERTING DRIVERS OF VEHICLES

The present invention relates to a method of alerting drivers of vehicles, and a warning system and warning arrangement for warning drivers of vehicles.

Background art

It is important to some situations that emergency vehicles such as police cars, fire trucks, ambulances and the like reach their destination as fast as possible. Thus, such emergency vehicles can make nearby vehicles aware of their presence by flashing light and a siren emitting an audio signal from the emergency vehicles so that nearby drivers of vehicles can see and hear the signals from the emergency vehicle and pull over to let the vehicle pass. This solution has shown to not always be sufficient in that e.g. loud music or another audio signal from a radio receiver inside nearby vehicles and/or inattentive drivers do not always hear or see the emergency vehicle in due time to react correctly. Also, the emitted audio signal and the flashing lights limit the area that the emergency vehicle can cover to warn relevant drivers of vehicles about the presence of a nearby emergency vehicle.

Also, it may generally be advantageous to warn drivers of vehicles of traffic issues at local geographical areas.

US 2003/0141990 discloses an emergency vehicle or a tracking centre transmitting position information to nearby vehicles, e.g. by use of GPS information, and a receiver of the nearby vehicles comprises means for analysing the position data.

GB2330989 discloses an emergency vehicle having RDS transmitter for transmitting a warning signal to vehicles nearby.

EP0774147 discloses an emergency vehicle that transmits signals to nearby vehicles, e.g. by means of utilizing parts from a RDS (Radio Data System) function. The signal from the emergency vehicle is transmitted at a tunable frequency of the receiver in the vehicle.

It is e.g. an object of the invention to enhance operation possibilities and/or provide further advantages in relation to warning drivers of vehicles.

Brief description of the invention

The invention relates to a method of warning drivers of vehicles, said method comprising: transmitting a traffic bulletin signal at a first predefined radio channel to one or more radio receivers of said vehicles, which one or more radio receivers comprise a Radio Data System facility, and transmitting at least one further radio signal being an interception radio signal, wherein said interception radio signal comprises information in the Radio Data System frequency range of a second radio channel being different from the first radio channel, wherein said information is different from information in the Radio Data System frequency range of a third radio signal transmitted from an external broadcasting station at said second radio channel, and wherein said information is configured so as to manipulate said radio receivers to automatically tune said radio receivers to said first radio channel to receive said traffic bulletin signal.

By the present invention, several advantages may be obtained. For example, by the above, emergency vehicles and other arrangements such as stationary arrangements located e.g. temporarily near a road, may transmit the interception signal(s) and traffic announcement signal to warn the drivers of nearby vehicles of e.g. traffic- related matter relevant to the local geographical area. So by the present invention it may be obtained that receivers e.g. not comprising an RDS feature and/or receivers being set to not receive RDS traffic information will not shift to receive the traffic bulletin signal. Hence unintended disturbance of receivers within range of the interception signal and/or traffic bulletin signal may be avoided. On the other hand, receivers where certain RDS features are enabled will be able to automatically shift to and receive a traffic bulleting of the traffic bulletin signal.

It may furthermore be achieved that listeners listening to a radio program (or a CD, a an audio data file such as MP3 files, WAW files and/or the like) may not notice that the receiver is receiving the interception signal, and the listeners hence will first notice a change when the receiver actually transmits a traffic bulletin of the traffic bulletin signal. Hence, unintended disturbance of an audio signal that the listeners may listen to may be avoided. This is preferably achieved by that the interception signal transmitted at the second channel does not comprise any audio signal in the S- band and/or M-band of the interception signal that will disturb the audio part of a radio signal that is transmitted at the same (second) channel by an eexternal broadcasting station and to be received at the same or near the geographical location that the traffic bulletin signal and/or same geographical location.

It is understood that for the term Radio Data System (RDS) is both to be understood the Radio Data System utilized e.g. in Europe, and the Radio Broadcast Data System (RBDS) being the official name used for the U.S. version of RDS. It is furthermore that the Radio Data System may also be referred to as "RDS" in the present document.

The channels that are used for transmittance of the interception signal and the traffic bulletin signal are different. For example, a receiver of a vehicle may be tuned to the channel of a radio program broadcasted on the second radio channel so that a listener in the vehicle can hear the audio signal of the radio program. Hence, to facilitate that the receiver(s) shifts to the first radio channel of the traffic bulletin signal, the interception signal is transmitted at the second radio channel which the receiver is tuned to. As one example, a receiver may be tuned to a radio channel at e.g. 100 MHz so that a radio program broadcasted at the S-band and/or M-band at this channel can be listened to by the driver, and hence the interception signal may hence be transmitted at the same channel, i.e. 100 Mhz.

Due to the information in the Radio Data System frequency range of the interception signal, the receiver may be manipulated to automatically shift to the first channel so that the receiver receive the traffic bulletin signal and so that a traffic bulletin of the traffic bulletin signal is given to the driver of the vehicle. The first channel is preferably an "empty" radio channel that is not used for broadcasting radio programs from stationary broadcasting arrangements at and near the geographical location from where the interception signal(s) and traffic bulletin signals(s) are transmitted. It is to be understood that the interception signal and the traffic bulletin signal are transmitted within the tunable FM range of the receivers, for example 87.5 to 108.0 MHz, 88.0 to 108.0 MHz, 76.0 to 90 MHz and/or the like dependent on where the present invention is to be used. Also, as described above, the information in the Radio Data System frequency of the interception signal may be different from information in the Radio Data System frequency range of the third radio signal transmitted from an external broadcasting station at the second radio channel. Hereby is understood that a radio receiver of a vehicle originally tuned to receive the third signal that may comprise RDS data may upon receipt of the interception signal be manipulated by the interception signal to shift to the traffic bulletin signal due to the information in the interception signal. So at least some of the information in the RDS band of the interception signal may be different from the information in the RDS band of the third signal to induce the receiver(s) to tune to the channel of the traffic bulletin signal. For example by manipulating one or more EON features of the RDS information in the interception signal, by the interception signal comprising a noise signal in the RDS band and/or the like.

In a preferred aspect of the invention, said method may comprise that the interception signal is configured so that radio receivers without Radio Data System facilities and receiving said interception signal continue to receive and broadcast an audio signal of said third signal.

Hence, a disturbance of audio signals of the third signal may be omitted where such disturbances are inappropriate. For example, receivers not containing a RDS facility are often stationary radio receivers where a listener may have no interest in listening to local traffic-related matters at local geographical areas. Also, it may be an advantage at local areas where a warning arrangement is arranged stationary at/near a road. This may e.g. be achieved by the interception signal not comprising signals in the S-band and/or M-band of the interception signal that will disturb the audio signal of the third signal. This may e.g. by filtering the interception signal by a filter arrangement comprising e.g. a bandpass filter so that signals in the S-band and/or M- band of the interception signal are removed or at least severely reduced. In a preferred aspect of the invention, said method may comprise that the information in the Radio Data System frequency range of said interception signal may be configured so that radio receivers with a Radio Data System Traffic Announcement facility disabled and receiving said interception signal continue to receive and broadcast an audio signal of said third signal while other receivers with the Radio Data System Traffic Announcement facility enabled and receiving said interception signal automatically tune to said first radio channel to receive said traffic bulletin signal.

This may e.g. be performed by the interception signal comprising RDS information such as a configuration of TA and TP flags set so as to have receivers with the Radio Data System Traffic Announcement facility turned on and receiving the interception signal to tune to the traffic bulletin signal. Hence receivers with this function disabled may not be disturbed unintentionally by the receiver shifting to the channel of the traffic bulletin signal upon receipt and processing of the information in the Radio Data System frequency range.

In advantageous aspects of the invention, said method may comprise that the information in the Radio Data System frequency range of said interception signal is configured so that radio receivers with a Radio Data System AF facility disabled and receiving said interception signal continue to receive and broadcast an audio signal of said third signal, while other receivers with a Radio Data System AF enabled and receiving said interception signal automatically tune to said first radio channel to receive said traffic bulletin signal.

The above aspects relating to the Radio Data System AF and/or the Radio Data System Traffic Announcement facility may e.g. be achieved by proper manipulation of the RDS facility of existing RDS receivers. E.g. by adding RDS data and/or noise to the RDS band of the interception signal(s) as described in more details later on.

In general, making it optional if the traffic bulletin signal is to be tuned to may be advantageous.

In preferred aspects of the invention, the method may comprise that the interception signal is configured so that that the information of an audio signal of said third signal is derivable from the output of receivers continuing to receive and broadcast an audio signal of said third signal while at the same time receiving said interception signal.

The audio signal of the third signal is preferably derivable in a way so that a listener by means of a receiver listening to the audio signal of the third signal from the external broadcaster would be able to continue to listen to the audio signal if the receiver does not comprises a RDS facility and/or with a RDS facility set so the receiver does not tune to the traffic bulletin signal upon receipt of the interception signal. Hence, a listener would not be annoyed by traffic bulletins that are not relevant to the listener and/or are deselected.

Alternatively, a measuring instrument connected to the audio output of the receiver receiving the interception signal but adapted so it does not tune to the traffic bulletin signal may be utilized for comparing the output from the receiver with the audio signal from the third signal to test if the audio signal is derivable.

In advantageous aspects of the present invention, method may comprise that the interception signal provides interference in the FM S-band and/or M-band of the interception signal that is at least 20dB such as 30 dB for example 40dB below an audio signal of said third signal registered by said receiver (3).

Hence, an audio signal of the third signal in the S-band or M-band may be broadcasted to the driver in an acceptable audio quality while the receiver at the same time receives the interception signal at the same channel.

In aspects of the invention, the method may comprise that the first radio channel and said second radio channel are spaced apart in transmission frequency by at least 200 kHz.

The FM broadcasting range ( e.g. 88-108 MHz) uses a channel spacing of 200 kHz, with a maximum frequency deviation of 75 kHz, leaving a 25 kHz guard band above the highest and below the lowest frequency to reduce interaction with other channels.

In aspects of the present invention, said method may comprise that the interception radio signal is established based on a predefined carrier frequency, wherein said predefined carrier frequency is modulated with said information in the Radio Data System frequency band. This may be an advantageous way of establishing the interception signal. The interception signal may for example be established digitally by digital means such as comprising a digital synthesiser or signal processor, by means of an analog signal generator and/or signal generators and/or by any other suitable means, by adjusting a frequency deviation as described in more details later on and/or the like.

In aspects of the invention, the said method may comprise that the interception signal is adapted so that the energy of the carrier and eventual M- and S- signals of said transmitted interception signal is reduced compared to the un-modulated carrier.

This reduction may be performed by adjusting the modulation index in e.g. the RDS frequency range, by means of filtering of the interception signal before transmittance and/or the like. In preferred aspects of the invention, the said method may comprise that the modulation index of said interception signal targeting the RDS information is preselected to a value so that the energy of a carrier of said transmitted interception signal is reduced while the energy in the sidebands from the RDS information in the interception signal is maintained.

It has come to the knowledge of the inventor that the RDS signal is very sensitive to disturbance, and also, the inventor has realized that the Bessel function indicates that at certain levels of FM-modulation of the carrier, the carrier of the transmitted signal may be significantly reduced so that the signal substantially only comprise energy in the side bands. Hence, the radiated power of the interception signal may be significantly reduced while the receivers still registers the information in the RDS band of the interception signal.

It may e.g. be possible hereby to reduce the transmission power by about 5 dB such as lOdB, for example 20dB or even more. By the term targeting as described above is to be understood that the RDS range at e.g. 57 kHz ± e.g. 2.5 kHz and/or 3.0 kHz may be utilized.

In advantageous aspects, modulation index is selected so that the energy of the carrier of the interception signal is reduced to less than 60% such as less that 35% for example less that 25% such as less than 10% compared to the un- modulated carrier.

In aspects, a modulation index of said interception signal may for example be selected to a value between 1.8-3.0, between 5.0-6.0, or between 8.0-9.0. At for example the mentioned levels of the modulation index, the carrier will be significantly reduced and hence the total radiated power of the interception signal may be reduced.

In aspects of the invention, the method may comprise that a filter arrangement reduces and/or removes frequency components in the S-band and/or M-band of said interception signal.

The filter arrangement may in aspects comprise a band pass filter with a cut off frequency so as to only allow energy in the RDS range to be transmitted, it may comprise a high-pass filter with a cut off frequency allowing said RDS information to be added to be contained in the interception signal while energy in the S-band and/or M-band of said broadcasted interception signal is reduced or avoided etc. It is to be understood that the filter arrangement in embodiments may comprise any suitable analog and/or digital filters or other suitable arrangements facilitating transmitting an interception signal comprising energy in the S-band and/or M-band that allows radios not tuned to the traffic announcement signal but still receiving the interception signal to broadcast an audio signal of the third signal in the S-band and/or M-band at a level that can be detected by a listener and/or suitable measuring devices. In aspects of the invention, the said method may comprise that the relationship between energy in the Radio Data System frequency band of said transmitted interception radio signal and the energy at a predefined carrier frequency of said transmitted interception radio signal is at least 2: 1, e.g. at least 10: 1, such as at least 100: 1, for example at least 1000: 1.

From the above is understood that there may be significantly more energy in the RDS band of the interception signal than at the carrier frequency. In aspects of the invention the said Radio Data System frequency band of said interception radio signal is located substantially at 57±2.5kHz and/or 57±3.0 kHz.

In advantageous aspects of the invention, the method comprises that information of said interception radio signal comprises a noise signal at said Radio Data System frequency range.

Some radio receivers of vehicles are adapted to tune to another station when a part of the signal of the third signal becomes weak. Hence, by adding the noise signal, the receiver may register this as the RDS information of the third signal becoming weak, and hence start to try to tune to another channel.

The noise signal may comprise white noise, grey noise or any other suitable noise pattern. The noise signal may be established by means of a noise generator and/or any other suitable means facilitating establishing a noise signal that facilitates triggering the receivers registering the noise signal to tune to the traffic bulletin signal, e.g. as described below.

In aspects of the invention, said noise signal is added to a first Radio Data System frequency side band of said interception signal. The noise signal is hence added to at least one of the side bands so as to disturb the RDS information from the central broadcasting station. This triggers RDS receivers to search for an alternative frequency. Generally it is understood that the amount of energy in the RDS side band(s) of the interception signal may be adjusted so as to facilitate adequate disturbance of the RDS signals of the third signal(s) while avoiding disturbance too far away from the location of the arrangement transmitting the interception signal. So the power of the interception signal may be a tradeoff between obtaining adequate and early enough RDS disturbance while avoiding transmitting the signal to too many irrelevant receivers. And this may again be dependent on the conditions that the system works under.

In preferred aspects of the invention the interception signal is configured so as to contain at least 2 times such as at least 5 times, e.g. at least 10 times such as at least 100 times, e.g. at least 1000 times more energy in the one of the RDS side bands of said interception signal compared to the energy in the other side band of said interception signal. It may be preferred that the noise signal is only located at one RDS sideband of the interception signal in that this will reduce disturbance of the audio signals at the channel that the vehicle is tuned to, and it may moreover result in a simpler solution for providing the interception signal. So hence noise may be added to one of the RDS side bands of the interception signal while noise in the other side band is omitted or significantly reduced compared to the noise in the other side band. Experiments have shown that it may be enough to only transmit RDS information in just one of the RDS side bands, and that this may trigger that the receivers search for an alternative channel. In further aspects of the invention, said noise signal may be added to both Radio Data System frequency side bands of said interception signal.

This may increases the amount of disturbance of the RDS information and hence it may facilitate a more reliable disturbance of the RDS content at the channel that the receivers are tuned to.

In advantageous aspects of the present invention, said noise signal comprises energy in a frequency range of said Radio Data System frequency side band, said frequency range of said noise signal being more narrow than the frequency range of said Radio Data System frequency side band.

This facilitates that disturbance of audio signals of the third radio signal at the second channel is reduced and even omitted while at the same time facilitating a disturbance of the RDS information of the third signal. And this may moreover reduce the energy needed In the interception signal for the disturbance.

In aspects, the frequency range of said noise signal may be at least 2 times such as at least 4 times, e.g. at least 5 times such as 10 times, e.g. 20 times smaller such as at least 100 times smaller or even smaller such as 1000 times smaller than the range of said Radio Data System frequency side band.

This e.g. reduces the energy needed to disturb the RDS part of the third signal In aspects of the invention, the noise signal may extend over a frequency range of at least 50Hz such as at least 100Hz, e.g. as at least 500 Hz, such as at least 1 kHz, for example, e.g. 1.25 kHz such as at least 2.5 KHz within the RDS frequency Range of said interception signal (4). The feature that the noise signal may extend over a plurality of frequencies within the RDS frequency range of the interception signal facilitates that a more reliable and efficient disturbance of the RDS signal may be facilitated. In aspects of the invention, said noise signal may extends over no more than 100 Hz, such as no more than 50 Hz, e.g. no more than 10 Hz such as no more than 5 Hz within the RDS frequency Range of said interception signal.

The feature that the noise signal may extend over just a few frequencies or may be located at substantially just one frequency within the RDS range of the interception signal may facilitate that enough disturbance of the RDS signal from the third radio signal is facilitated while substantially no disturbance in the audio part of the third signal is facilitated. Moreover, it may provide a more cost efficient and/or simple system may be achieved in that it is more simple to add a noise signal to the inception signal that does not need to extend over a larger frequency range.

In general, it is also noted that the less frequencies that the noise signal extends over the less energy may be needed to transmit the interception signal while at the same time providing sufficient disturbance of the RDS part at the channel that a receiver listens to. Hence an efficient interception signal with a reduced transmittance power may be achieved. It has generally come to the inventors knowledge that the disturbance of the RDS part in the RDS range may be facilitated by means of a very narrow frequency range of the noise signal so that the noise signal is more narrow than the range of a RDS side band, e.g. as described in the different aspects above.

In further aspects of the invention, one or more stationary broadcasting stations transmits channel information and a RDS Program Identification code of said traffic bulletin signal to said radio receivers so as to enable said receivers to automatically tune to said traffic bulletin signal when receiving said interception radio signal. This information from the broadcasting stations is preferably automatically stored in e.g. the AF lists of said radio receivers by the broadcaster, so that when for example the noise signal as described above is registered by the receivers, they will turn to look in the AF list for an alternative frequency transmitting the same program and hence be guided to tune to the channel of the traffic bulletin signal instead.

The reason for this is that when the receivers registers a bad RDS signal as the noise signal will be interpreted as, the receivers sees this as the radio signal from the broadcasting station getting to weak/disturbed. Hence, the receivers may look for an alternative channel in the AF list and would preferably find the channel and PI code of the traffic bulletin signal. Hence, it is preferred that the PI code of the traffic bulletin signal is preferably identical to the PI code of the channel that the receiver is tuned to upon receipt of the interception signal. In advantageous aspects of the invention, the method may comprise that said information of the interception radio signal comprises Radio Data System data.

For example, the radio system Data may comprise RDS information and commands. Hence, such a signal may be considered as a kind of spoofing signal where the RDS information masquerades as RDS information of a stationary broadcaster and hence inducing the radio receivers receiving the signal to tune to the traffic bulletin signal without interfering audio signals of the stationary broadcaster or at other broadcasting channels. In further aspects of the invention, said interception signal comprises Enhanced Other Network data of the RDS system.

The Enhanced other Network (EON) facility of the RDS system provides some opportunities of having a receiver to temporarily tune to another station to receive a traffic announcement or another message. Hence, utilizing parts of the EON facility, it may be possible to manipulate the receivers receiving the interception signal to tune to the channel/frequency of the traffic bulletin signal.

In further advantageous aspects of the invention, said interception signal comprises EON data configured so that receivers with RDS traffic announcement features in EON enabled will tune to said first predefined radio channel, and wherein receivers with RDS traffic announcement features in EON disabled will stay tuned to said second channel. Hereby, receivers having the TA feature enabled and receiving the interception signal would try to tune to the channel of the traffic bulletin signal, whereas receivers having the TA feature disabled and receiving the interception signal may remain tuned at the second channel. In general it is also to be noted that when the traffic bulletin becomes weak (as seen from the receiver), most RDS receivers will first go back to the originally selected frequency regardless of PI and may also therefore return to the program before interception. In aspects of the invention, the method may comprise that said Radio Data System data comprises an identification of the broadcast channel of said traffic bulletin signal to be implemented in an Alternative Frequency list of said radio receivers

Hereby may be achieved that radio receivers receiving the interception signal will automatically tune to the broadcast channel of said traffic bulletin signal.

In advantageous aspects of the present invention, said Radio Data System data may comprise a program identification code of said traffic bulletin signal. Hereby may be achieved that radio receivers receiving the interception signal may stay tuned to broadcast traffic bulletins of the traffic bulletin signal, in that the receiver may correlate the program identification code with the program identification code of the received traffic bulletin signal.

In further advantageous aspects of the invention, the method may comprise that the Radio Data System data of the interception signal comprises a TA flag and/or other EON features indicating a currently active traffic announcement.

Hence, the interception signal may in this way initiate the receivers receiving the signal to look for the traffic bulletin signal.

In aspects of the invention, said Radio Data System data may comprise a RDS TP flag set so as to indicate that said traffic bulletin signal is considered as transmitting a traffic announcement.

This may e.g. be advantageous in relation to utilizing e.g. the EON feature of the RDS system, in that the TP flag may hence be used for indicating that the traffic bulletin signal is to be considered as comprising a radio program transmitting traffic announcements.

In aspects of the invention, the method may comprise said traffic bulletin signal comprises RDS data to be received and processed by said receivers.

This may be advantageous in relation to controlling if the receivers should stay tuned to the channel of the traffic bulletin system and/or if the receivers e.g. return to the previous channel.

In advantageous aspects of the invention, said traffic bulletin signal comprises a RDS traffic program flag set so as to enable that said one or more radio receivers consider the traffic bulletin signal as a traffic service signal, and/or a traffic program flag set so as to ensure that said one or more receivers tuned to receive the traffic bulletin signal remain to be tuned to the said traffic bulletin signal. It may be especially advantageous to have the traffic bulletin signal comprising RDS information so that the receivers, e.g. as long as the TA flag of the traffic bulletin signal is set to "1", will stay tuned to the traffic bulletin signal to receive the traffic bulletin of the traffic bulletin signal. Also, having a TP flag in a traffic bulletin signal set to "1" may help to have the receivers stay tuned to the channel of the traffic bulletin signal.

In an aspect of the invention, said traffic bulletin signal may comprise a RDS PI code, and wherein a RDS PI code identical to the RDS PI code of the traffic bulletin signal is stored in said receiver(s) so that the receiver(s), when tuning to the traffic bulletin signal accepts the PI code of the traffic bulletin signal.

Radio receivers comprising a RDS facility may be configured for utilizing RDS PI codes for verifying a traffic program that they tune to. Hence, manipulating such receivers may e.g. help to have the receivers tune to the traffic bulletin signal.

In an aspect, the PI code of the traffic bulletin signal may be adapted so as to be identical to the PI code of the radio program that the receiver was tuned to before shifting to the channel of the traffic bulletin signal due to receipt of the interception signal.

In advantageous aspects of the invention a PI code of the traffic bulletin signal is stored in the receiver by means of RDS information in radio signals from an external broadcasting arrangement and/or by means of RDS data in the interception signal.

Having a PI code of the traffic bulletin signal stored in the receiver by a radio signal transmitted from an external broadcasting arrangement may e.g. be advantageous in relation to having the receiver tune rapidly to the channel of the traffic bulletin signal. Having a PI code of the traffic bulletin signal stored in the receiver by RDS data in the interception signal may e.g. be advantageous to facilitate that the system may work by a warning arrangement without the need of external broadcasters broadcasting to specify PI codes of the traffic bulletin system.

In advantageous aspects of the invention, said method may comprise that scanning means scan the FM frequency band within the tunable range of said receivers for one or more channels to be utilized for broadcasting said interception signal and/or said traffic bulletin signal.

Hence, one or more interception signals may be transmitted on channels selected based on the scanning, thus e.g. facilitating local channel adjustment so that the warning arrangement can fit in to the radio environment at the geographical area where it is present. This aspect may furthermore be especially relevant where the interception signal(s) and the traffic bulletin signal are transmitted from a vehicles such as an emergency vehicle since continuous local channel adjustment of the traffic bulletin signal and/or the interception signals) may due to the movement of the vehicle. It may be advantageous to continuously scan for proper and preferably empty channels for use for the traffic bulletin signal.

In aspects of the invention, the method comprises the step of at the location from where the interception signal is transmitted detecting the signal strength of a signal from an external broadcasting arrangements at said second channel, and wherein the signal strength of said interception signal and/or traffic bulletin signal is adapted based on this scanning.

Hereby, it may be possible to adapt the signal strength of the interception signal and/or traffic bulletin signal to avoid unnecessary high transmittance strength of the interception signal, thus avoiding disturbing receivers at locations where the traffic bulletin may not be considered relevant.

In preferred aspects, the scanning may be performed continuously, with a predefined time interval and/or the like.

In aspects of the invention a plurality of interception signals may be transmitted at different channels. Hence, receivers tuned to different channels to receive different radio programs may all be automatically tuned to receive the traffic bulletin signal. This facilitates that more receivers may shift to receive the traffic bulletin of the traffic bulletin signal.

In further aspects of the invention, the method may comprise that the said traffic announcement signal and/or said interception signal are transmitted from a vehicle such as an emergency vehicle.

Hence, drivers of vehicles receiving the traffic bulletin of the traffic bulletin signal are made aware of the presence of a nearby emergency vehicle e.g. acting on e.g. an emergency response. Preferably the traffic announcement signal and said interception signal are transmitted from the same emergency vehicle.

In aspects of the invention, said traffic bulletin signal(s) and/or said interception signal(s) may be transmitted from a stationary location.

This may be relevant in relation to e.g. accidents at roads where authorized personnel may want to arrange the device to e.g. temporarily warn nearby drivers by the traffic bulletin signal that they should e.g. slow down and pay attention. This may hence improve safety of the working personnel at the location of the accident and/or the drivers of vehicles comprising receivers receiving a traffic bulletin of the traffic bulletin signal. In an aspect of the invention, a positioning arrangement detects a geographical position and an adjustment of the channel for transmittance of said interception signal and/or traffic bulletin signal is performed based thereon.

Hence, an advantageous way of determining proper channels for transmitting the interception signal and/or traffic bulletin signal may be identified.

In aspects of the invention the method may furthermore comprise a TCM decoding.

Hence, such TCM (Traffic Message Channel) information may be utilized in relation to adapting the interception signal and/or traffic bulletin signal.

In aspects of the invention, RDS information of radio signals from one or more external broadcasting stations may be received and processed e.g. so as to identify relevant channels for transmittance of said traffic bulletin signal traffic bulletin signal and/or said interception signal.

The RDS information of such external broadcasting stations may provide advantageous information regarding how to transmit the traffic bulletin signals and/or the interception signal. Hence, by processing the RDS information, it may be possible to identify relevant radio stations for transmittance of the traffic bulletin signal and/or the interception signal(s), it may be used to update RDS information of the traffic bulletin signal and/or the interception signal(s) or the like. Hence, by processing the RDS information, a local adaption of the traffic bulletin signal and/or the interception signal(s) may be performed so that these signals are adapted to the conditions at the location of the transmission of the traffic bulletin signal and/or the interception signal(s). Alternatively, the channels, Pi-codes, channels and the like of the traffic bulletin sugnal and/or the interception signal may be determined based on a pre-established look up table and e.g. being dependent on the location for transmitting the signals. In aspects of the invention, said processing of said RDS information may comprise processing of AF list information of said RDS information, and wherein a channel for transmitting said traffic bulletin signal and/or said interception signal is selected based on said processing. In aspects of the invention, said traffic bulletin signal and/or said interception signal is transmitted at a channel selected by means of said processing of said RDS information.

This may be advantageous in that the RDS information may comprise channel information such as AF list information or the like that may contain information of the most relevant channels for transmitting the traffic bulletin signal and/or the interception signal(s).

The RDS information is preferably processed at the location of the transmittance of the bulletin signal(s) and/or interception signal(s), and in aspects of the invention the transmittance of these signals may be updated over time. The processing of the RDS signal(s) is preferably performed continuously such as with a predefined interval or the like. The warning arrangement according to aspects of the present invention may in advantageous aspects comprise means for processing of the RDS information to select a suitable channel, PI code or the like.

In aspects of the invention, RDS information of one or more radio signals from one or more external broadcasting stations is received and processed so as to identify one or more RDS PI codes of said radio signals, wherein a PI code of the traffic bulletin signal is adapted based on said identified PI codes. In aspects of the invention, RDS information of one or more radio signals from one or more external broadcasting stations may be received and processed so as to identify the status of a TA flag of said one or more radio signals. Hence, the TA flag of the Traffic bulletin signal may be adapted based on the registered TA flag setting, which may facilitate a more reliable control of the receivers by means of the traffic bulletin signal. In further embodiments of the invention, the TA flag may be a determining factor in determining whether to transmit the bulletin signal or not. If A TA flag is registered as active, the warning arrangement may temporarily stop transmitting the interception signal and/or the traffic bulletin signal until the TA flag is set inactive again. This may e.g. be relevant in situations where traffic announcements from external broadcasting stations are considered as more important than the traffic announcements transmitted from an emergency vehicle.

The invention furthermore relates to a warning system for warning drivers of vehicles, said system comprising: a plurality of radio receivers arranged at said vehicles, which radio receivers comprise a Radio Data System facility, and one or more stationary broadcasting stations configured for transmitting radio signals at one or more predefined radio frequencies to one or more radio receivers of, said vehicles, and a broadcasting arrangement, said broadcasting arrangement being configured for: transmitting a traffic bulletin signal at a first predefined radio channel to one or more radio receivers of said vehicles, which one or more radio receivers comprise a Radio Data System facility, and transmitting at least one further radio signal being an interception radio signal, wherein said interception radio signal comprises information in the Radio Data System frequency range of a second radio channel being different from the first radio channel, wherein said information is configured so as to manipulate said radio receivers to automatically tune said radio receivers to said first radio channel to receive said traffic bulletin signal. Also, the invention relates to a warning system as described above being configured for operating in accordance with a method according to one or more of the above mentioned aspects and/or a method according to one or more of the claims of this document such as claims 1-45. Furthermore, the invention relates to a warning arrangement for warning drivers of vehicles, said warning arrangement being configured for: transmitting a traffic bulletin signal at a first predefined radio channel to one or more radio receivers of said vehicles, which one or more radio receivers comprise a Radio Data System facility, and transmitting at least one further radio signal being an interception radio signal, wherein said interception radio signal comprises information in the Radio Data System frequency range of a second radio channel being different from the first radio channel, wherein said information is configured so as to manipulate said radio receivers to automatically tune said radio receivers from a third radio signal broadcasted from an external, stationary broadcasting station at said second channel to said first radio channel to receive said traffic bulletin signal. Also, the invention relates to a warning arrangement as described above configured for operating in accordance with a method according to one or more of the above aspects and/or a system according to one or more of the above aspects, and/or a method according to one or more of the claims of this document such as claims 1-45.

The invention may furthermore relate to a method of warning drivers of vehicles, said method comprising: transmitting a traffic bulletin signal at a first predefined radio channel to one or more radio receivers of said vehicles, which one or more radio receivers comprise a Radio Data System facility, and transmitting at least one further radio signal being an interception radio signal, wherein said interception radio signal comprises information in the Radio Data System frequency range of a second radio channel being different from the first radio channel, wherein said information is configured so as to manipulate said radio receivers to automatically tune said radio receivers to said first radio channel to receive said traffic bulletin signal. Also, it is to be understood that this method may be combined with a method according to one or more of the above aspects and/or a warning system and/or a warning arrangement according to one or more of the above aspects, and/or a method according to one or more of the claims of this document. The invention may furthermore also relate to an emergency vehicle comprising a warning arrangement as disclosed in one or more aspects of this document.

In a further aspect, the invention relates to a method of adapting transmittance of a traffic bulletin signal and/or an interception signal so as to warn drivers of vehicles, said method comprising the steps of: receiving one or more radio signals transmitted from an external broadcasting station, processing RDS information of said one or more radio signals, adapting said traffic bulletin signal and/or an interception signal based on said RDS processing, and transmitting said traffic bulletin signal and/or said interception signal to one or more receivers of vehicles. This e.g. provides advantageous adaption to the conditions at the location where signals to warn drivers of vehicles is/are transmitted. Moreover, this may provide advantages in relation to systems where a traffic bulletin signal is configured for overruling a radio signal that a receiver is tuned to.

According to an aspect of the above further aspect, said traffic bulletin signal and/or said interception signal comprises RDS data such as one or more RDS PI codes or TA flags, which are adapted based on said RDS processing. According to an aspect of the above further aspect, said traffic bulletin signal and/or said interception signal are transmitted at a radio channel identified by means of said RDS processing.

According to an aspect of the above further aspect, the method comprises transmitting said traffic bulletin signal at a first predefined radio channel to one or more of said radio receivers of said vehicles, transmitting the interception radio signal wherein the interception radio signal comprises information in the Radio Data System frequency range of a second radio channel being different from the first radio channel, wherein said information is different from information in the Radio Data System frequency range of a third radio signal (5) transmitted from an external broadcasting station at said second radio channel, and wherein said information is configured so as to manipulate said radio receivers to automatically tune said radio receivers to said first radio channel to receive said traffic bulletin signal.

According to aspects of the above further aspect, the method may comprise one or more of the steps of claims 1-45. According to aspects of the above further aspect, said traffic bulletin signal and/or said interception signal is/are transmitted from a vehicle such as an emergency vehicle. In general it is to be understood that the present invention in preferred aspects is utilized for radio receivers in vehicles in the form of, FM (frequency modulation) radio receivers. Such receivers may furthermore also comprise an AM (Amplitude Modulation) feature for receiving and broadcasting AM radio signals from stationary broadcasting arrangements, a DAB (Digital Audio Broadcasting) feature for receiving and broadcasting DAB radio signals, and/or any other suitable feature for receiving different types of radio signals. Hence, the RDS feature and FM features of such receivers may be utilized as described by the present invention. In such embodiments, such receivers may monitor the RDS information of FM signals and may hence be adapted for shifting to the radio channel of the traffic bulletin signal upon receipt and processing of the information in the RDS band of the interception signal, and hence shifting from an FM signal, AM signal, DAB signal and/or the like to the traffic bulletin signal.

It is furthermore generally understood that the traffic bulletin signal(s) and/or interception signal(s) preferably are FM radio signals.

It is to be understood that the disclosed aspects above may be combined in a multitude of varieties so as to provide aspects of e.g. a method of warning drivers of vehicles, a warning system for warning drivers of vehicles and/or a warning arrangement for warning drivers of vehicles.

Figures

Aspects of the present disclosure will be described in the following with reference to the figures in which: Fig. 1 : illustrates an embodiment of the invention according to aspects of the invention,

fig. 2 : illustrates a diagrammatic representation of a FM base band signal according to aspects of the invention,

fig. 3 : illustrates an embodiment of an interception signal transmitted from a warning arrangement according to aspects of the invention,

fig. 4 : illustrates a flow-chart relating to embodiments of a process of transmitting an interception signal and a traffic bulleting signal according to aspects of the invention,

fig. 5: : illustrates a flow-chart relating to embodiments of adding a noise signal to an interception signal according to aspects of the invention,

: illustrates a flow-chart relating to embodiments of adding RDS data to an interception signal according to aspects of the invention.,

: illustrates five radio programs where one of these is a radio bulletin signal transmitted from a warning arrangement according to aspects of the invention.

fig. 8 : illustrates an embodiment where multiple interception signals are transmitted at different radio channels according to aspects of the invention, : illustrates embodiments of a warning arrangement according to aspects of the invention, and

: illustrates different embodiments of adding noise to an interception signal according to embodiments of the invention.

Detailed description of the invention

Fig 1 illustrates a preferred embodiment of the invention. The warning system of the present invention system comprises a warning arrangement 10 configured for transmitting a traffic bulletin signal 2 at a first predefined radio channel to one or more radio receivers 3 in vehicles 1.

The warning arrangement 10 is furthermore configured for transmitting a further radio signal in the form of an interception radio signal 4. The interception radio signal 4 comprises information in the Radio Data System frequency range of a second radio channel being different from the above mentioned first radio channel of the traffic bulletin signal. This information of the interception signal 4 may be different from information in the Radio Data System frequency range of a third radio signal 5 transmitted from an external broadcasting station 6 at the second radio channel. The said information of the interception signal 4 is hence configured so as to manipulate radio receivers 3 receiving the interception signal to automatically tune to the first radio channel to receive the traffic bulletin signal 2. As can be seen from fig. 1, the warning arrangement 10 may be placed in an emergency vehicle 11 such as an ambulance, a fire truck, a police car (and/or police motor cycle) and/or any other suitable emergency vehicle 11 or other suitable transportation means so as to warn drivers of nearby vehicles 1 of the emergency vehicle approaching or being nearby. In embodiments, the warning arrangement 10 may be implemented in a dash-board of an emergency vehicle 11 and consume power from the power supply of the vehicle 11, it may be arranged in its own casing that may be installed in the emergency vehicle 11 external to the dashboard and may e.g. be connected to the power supply of the emergency vehicle 11 and/or the like. In further embodiments of the invention, the warning arrangement 10 may be located in e.g. a casing configured for/facilitating being e.g. portable to be temporarily arranged at a local geographical location and/or it may be configured or being substantially permanently arranged near a road to warn drivers of approaching vehicles 1 by means of the radio receiver 3 of the vehicles.

Also, in embodiments, the warning arrangement may comprise its own power supply in the form of one or more batteries that may be replaceable and/or rechargeable by a power supply external to and connected to a power input of the warning arrangement so as to achieve a stand-alone device.

So the warning arrangement may be a portable device, it may be a device incorporated in/to be incorporated in a dashboard of e.g. a vehicle, it may be a device for being arranged outdoor at a stationary location near one or more roads to warn drivers of vehicles and/or the like.

The broadcasting station 6 may be a conventional broadcasting station transmitting radio signals 5 at one or more predefined channels by means of one or more antennas 7. These signals 5 are to be received and processed by radio receivers 1. The radio signals 5 may e.g. comprise a radio program at a predefined channel such as commercial radio programs. The radio receivers 3 are hence adapted for identifying and broadcasting audio signals of the radio signal 5 to listeners such as the driver and passengers in the vehicle 1. Also, radio receivers 3 comprising a Radio Data System (RDS) facility may be set to process Radio Data System information in the RDS band of the radio signal 5 (if such a signal is present in the signal 5). It is to be understood that the warning arrangement 10 is external to such conventional broadcasting stations 6.

The traffic bulleting signal 2 comprises a traffic bulletin e.g. comprising an audio signal for being broadcasted to the radio receivers 3 tuned to and within the range of the traffic bulletin signal 2. This audio signal may comprise a siren audio signal, a prerecorded audio message where a person has recorded an audio message, an audio signal detected by a microphone connected to the warning arrangement so that drivers of the emergency vehicle may record/speak messages into the microphone to be broadcasted substantially in real-time to the nearby drivers to be warned by means of the traffic bulletin signal 2 as it is registered by the microphone and/or the like.

It is understood that the channel(s) of both the traffic bulletin signal and the interception signal are preferably located within the tuneable range of the receivers 3.

The warning arrangement 10 may be connected to means controlling e.g. a siren and/or blinking light of the emergency vehicle 11 so that it is automatically turned on to transmit the signals 2, 4 when the siren and/or blinking light is turned on. In embodiments, the warning arrangement 10 may also be turned on and off manually by an operator in e.g. the emergency vehicle.

In further embodiments, the warning arrangement 10 may be controlled wired or wirelessly, so that e.g. an operator located at an emergency central or another location may turn the device on and off from a location remote too the location of the warning arrangement 10. This may e.g. be advantageous in embodiments where the warning arrangement 10 may be configured for be arranged temporarily and/or substantially permanently at a geographical location. In the following, a more detailed description of advantageous embodiments of the invention is described. As known in the art, FM radio signals for the radio receivers 3 may be modulated by an audio signal. This signal is conventionally transmitted from a conventional broadcasting arrangement 6, and comprises a base band signal in a range of about 20 Hz to 15 KHz that is frequency modulated on the carrier, i.e. a signal with a +/- 75 kHz maximum deviation from the center frequency. This leaves 25 kHz upper and lower "guard bands" to minimize interaction with an adjacent frequency band. Hence, the distance between FM radio programs is normally about 200 kHz. The base band signal may also contain a S-signal for stereo. This is modulated on a suppressed carrier of 38 KHz and inserted in the base band signal. Finally a pilot tone of 19 KHz, for synchronization, and a RDS signal also on a suppressed carrier at 57 KHz, may be inserted in the base band. See fig. 2.

Fig. 2 illustrates a diagrammatic representation of a FM base band signal. As can be seen from fig. 2, the base band signal may comprise the following:

• A: A Main Channel Mono signal (left+ right audio channel) in the range of 30 Hz to 15 kHz. This part is also known as the M-signal.

• B: A predefined pilot tone of 19 kHz.

• C: A Sub-channel difference signal (left - right) in the range of 23 kHz to 52 kHz. This part is also known as the Stereo signal or S-signal. This part is located at/around a suppressed 38 kHz sub-carrier being a 2^nd harmonic of the 19 kHz pilot tone B.

• D: A 57±2.5 kHz Radio Data System signal. This signal is located at a 57 kHz sub-carrier (3 harmonic of the 19 kHz pilot tone).

In the following different embodiments of establishing the interception signal 4 is described in relation to establishing the carrier of the interception signal:

The modulation index "m" indicates by how much a modulated frequency varies around its un-modulated frequency, such as a carrier wave. The modulation index is given by the following equation:

m=— fd

fm where m is the modulation index, fd is the frequency deviation and fm is the modulation frequency. For example, the highest modulation frequency in mono audio broadcasting is 15 KHz, resulting in a modulation index m= 75/15= 5. It is to be noted that the size of m for FM indicates the signal's ability to withstand noise and interference. Typical the interference resistance for a FM signal is proportional to m, compared to AM (amplitude modulation). A small m, as for the RDS signal as calculated in the following, indicates that the RDS signals are highly sensitive/ susceptible to interference.

The carrier wave for the RDS- or RBDS information is located as a narrow-band FM signal at a suppressed sub-carrier at 3 times the predefined pilot tone of 19 kHz, i.e. a 57 kHz subcarrier as seen in fig. 2. The frequency deviation FdRDs of the RDS signal is predefined to be e.g. ±2.5 kJTZ. Given the above, the modulation index of the RDS as seen in the base band for the 57 KHz subcarrier, is:

m = =— = 0,0438.

fm_RDs 57

On the carrier, the level after demodulation for the 57 KHz composite RDS signal is about -40 dB compared to max +/- 75 KHz for FM carrier thus being 75KHz/100= 0,75 KHz. Giving M (rds)= 0,75/57= 0,0132.

The above calculations indicate that the RDS information is a very narrow band FM signal. Hence, even weak radio signals in the sidebands + and - 57 KHz added to or interfering with a carrier can severely harm the RDS reception due to the very low modulation index of the RDS signal.

A signal containing only the two RDS sidebands will thus be able to interfere with the RDS reception without disturbing the Mono- audio and S-stereo signals of the received FM program, if omitting transmitting or by at least reducing a carrier and signals in the base band of the interception signals equivalent S-band (23kHz to 52kHz) and/or M-band (30 Hz to 15 kHz.) as illustrated in fig. 2.

Given the above, a signal may be generated, containing only the equivalent around the 57 KHz RDS sidebands, but the carrier itself may be suppressed by using some facts of FM modulation:

At certain levels of modulation where the modulation index is e.g. about for example 2.41, it appears that the carrier of a signal falls substantially to a figure of zero, so that the signal is substantially being comprised by the sidebands. Hence, by adjusting the frequency deviation of the carrier wave fc to obtain a modulation index of for example 2.41, this will substantially remove the carrier wave from the composite signal. Such a signal hence being able to "intercept" only the RDS signal from e.g. a broadcasting station.

The adjustment of the modulation index to a desired value may be performed by adjusting the frequency deviation due to the following equation:

fd

m = -— <= fd = fm * m

fm

Hence, to achieve a modulation index of 2.41 for 57 KHz, on a carrier signal at for example 100 MHz, the frequency deviation fd should be about:

fd = fm * m = 57 KHz * 2.41 = 137,37 KHz.

In this case severe side bands are generated in the neighbor channels, so proper filtering removing anything outside +/- 75 KHz is preferred.

Also, in embodiments, it is to be preferred that a filtering is performed during establishing of the interception signal 4, where the filter arrangement comprises a characteristic that allows signals in the RDS band of the interception signal to be transmitted from the warning arrangement 10 and then be received and processed by receivers 3 while signals at frequencies in the S-band and/or M-band of the interception signal 4 are damped at least 10 dB such as at least 20dB, for example at least 40dB. This may be achieved with e.g. a proper designed band pass filter e.g. as described in more details later on in this document. Hence, establishing an interception radio signal 4 based on a carrier wave 20 (see fig. 3), where the modulation index is e.g. about 2.41, and modulating this carrier signal 20 with a signal at the RDS frequency band (57kHz±2.5kHz) (or ±3.0 kHz) would provide advantages in relation to the power needed to manipulate the RDS facility of radio receivers 3 if interception was conducted on the carrier itself. The reason for this is that such a signal would look substantially as illustrated in fig. 3 where the carrier 20 of the interception signal 4 is significantly reduced or even close to zero. The interception signal 4 hence contains energy in the equivalent 57 KHz RDS sidebands, while the energy at the carrier 20 is substantially zero or at least significantly reduced.

At certain other values of a modulation index such as e.g. substantially around 5.53, 8.65 and further higher specific levels of the modulation index that may be identified, the carrier will also fall substantially to zero or at least be significantly reduced, and hence the same as described above may be obtained by adjusting the frequency deviation and thereby the modulation index.

The amount of energy at the carrier frequency 20 compared to other frequencies in the signal 4 is dependent on the selected modulation index as explained above. By studying the Bessel function, further advantageous values of the modulation index may be identified to obtain a reduced carrier. For example, in embodiments of the invention, the modulation index may be preselected to a value between 1.8-3.0, between 5.0-6.0, or between 8.0-9.0. In an embodiment of the invention, a modulation index may be selected so that the amplitude of the carrier 20 is reduced to being less than 50% such as less that 35% for example less that 25% such as less than 10%) compared to the un-modulated carrier (i.e. a modulation index of zero) by adjusting the frequency deviation. However, in embodiments of the invention, de modulation index may be selected so that the carrier is substantially zero and so that the interception signal 4 substantially only comprise energy in the RDS side-bands 21a, 21b as seen in fig. 3. Also, it is to be understood that in embodiments of the invention, the modulation index may be selected to a value where the amplitude of the carrier is not zero, but is reduced compared the un-modulated level of the carrier.

As mentioned both above and later on, the establishing of the interception signal 4 is preferably followed up by a suitable filtering to keep the interception signal inside the boundaries of the FM channel to be intercepted and not disturbing neighbor channels. Such a filtering may comprise a kind of bandpass filtering, e.g. by a filter arrangement having a substantially 200 kHz bandwidth or any other suitable bandwidth and having suitable cut-off frequencies. It is to be understood that in fig. 3, the reference 21a refer to the RDS signal in the lower sideband of the interception signal 4, i.e. the carrier 20 - 57 kHz, whereas the reference 21b refer to the RDS signal in the upper sideband of the interception signal 20, i.e. the carrier 20 + 57 kHz. The reference 22a refers to the -2.5 kHz of the lower RDS sideband 21a, whereas the reference 23a refers to the +2.5 kHz of the lower RDS sideband 21a. In the same way, the reference 22b refers to the -2.5 kHz of the upper RDS sideband 21b, whereas the reference 23b refer to the +2.5 kHz of the upper RDS sideband 21a. Hence, the lower sideband 21a constitutes a -57+2.5 kHz signal and the upper sideband 21b constitutes a +57+2.5 kHz signal compared to the carrier 20.

In general, it is to be understood that in some countries/regions, a substantially ±3 kHz frequency deviation of the RDS signal may be used instead of the ±2.5 kHz as indicated earlier. In such countries the interception signal may be adapted accordingly. In fig. 3, the parts of the interception signal are illustrated as the radiated power as a function of the frequencies of the interception signal.

Another way of establishing the interception radio signal may comprise establishing two signals at different carrier frequencies, being the carrier to be intercepted minus 57 KHz for the one and +57 KHz for the other, where the two signals has a substantially 90° mutual phase shift,. Hence, combining these two signals would result in an interception radio signal where the carrier is substantially reduced or even substantially zero, while the + and -57 kHz signals is substantially maintained in the side bands of the two carries. Thus the signal established hereby may intercept the signal from the external broadcasting arrangement exactly in the sidebands where the original RDS information of the radio signal from the external broadcasting arrangement is located, whereas the carrier would be reduced or substantially zero. A further way of establishing the interception radio signal may comprise establishing it by digital means such as comprising a digital synthesiser or signal processor arrangement being manipulated to establish a signal mainly or solely comprising energy at the RDS frequency range, i.e. being the carrier to be intercepted +/- 57kHz±2.5 kHz ( the latter being the RDS modulation content).

Common to the different ways of establishing the interception signal 4, e.g. as described above is preferably that the interception signal 4 may be established based on a carrier, where the energy at the carrier frequency 20 when the interception signal 4 is broadcasted is significantly reduced.

Now, turning to the content of the signal in the RDS sideband of the interception signal 4, the RDS sidebands 21a may comprise different types of information to manipulate the RDS radio receivers 3 to automatically tune the radio receivers 3 to the channel of the traffic bulletin signal 2. Utilizing the RDS facility of the radio receivers 3 to automatically tune the radio receivers 3 to the channel of the traffic bulletin signal 2 may be done in various ways as described in the following. In the following, some features of the RDS system is described in more details.

The RDS system among other provides a traffic service. This service is facilitated by an Enhanced Other Networks (EON) feature in the RDS system, also referred to as EON feature in the following. The EON feature is designed to allow the RDS system to become "intelligent". The basic function of EON, is to build up a database of information about other transmissions and, if appropriate, to place it into a database in a memory of receivers 3. The EON feature defines a relation between associated radio programs, and allows a receiver to monitor other radio programs for traffic programs, and automatically temporarily tune into that station.

EON radio programs transmit a Traffic Program flag TP, also referred to at TP flag in the following. The TP flag identifies programmes that, from time to time, carry messages addressed to motorists. Such messages are e.g. traffic announcements in a transmitter network. The receiver 3 uses this information to identify a radio program that transmits traffic announcements. If the TP flag is set, the program is used for transmitting traffic announcements.

EON radio programs may furthermore transmit a Traffic Announcement flag TA also referred to as TA flag in the following. The TA flag is an indicator for a currently active traffic announcement. The receiver 3 of a vehicle 1 can act in different ways when receiving this information. If the receiver 3 is tuned to a traffic program P4 and receives the TA information it usually turns up the volume until the traffic announcement is over. If the receiver is not tuned to a traffic program, the receiver switches to the program until the traffic announcement is over.

Table 1 below indicates status of traffic announcement features of the RDS system dependent on the status of the TP flag and the TA flag. Table 1

An EON radio program also transmits a Program Identification code PI, also referred to as PI code in the following. The PI code is a 16-bit code comprising a country symbol, a regional code, and a number permitting the identification of the broadcaster and the particular programme, and may thus be regarded as a unique identifier for a radio program. PI codes are assigned in such a way that receivers automatically can tune to other transmitters radiating the same program by identifying the same Programme Identification Code, that is, all 16 bits should be identical. It is to be understood that PI codes given in this document are only examples, and that any other suitable PI codes may be utilized.

RDS Radio receivers furthermore often comprises an AF (Alternate frequency) lists to facilitate automatic tuning of an RDS receiver 3 to the same radio program at different predefined channels/frequencies when the first signal becomes too weak.

The AF list thus indicates carrier frequencies on which a specified service is broadcasted. AF lists may be broadcasted for a tuned service and also for other services using the EON feature. The receivers 3 may ascertain the suitability of each frequency in the AF list by evaluating the signal quality and decoding the PI code to check that there is an exact match before switching frequencies automatically.

It is to be noted that the RDS system utilizes data groups to transmit data relating to among other things the traffic announcement feature facilitated by the RDS system. Such data groups includes among others data group types 14A and 14B of the RDS system which are utilized in relation to the traffic announcement feature facilitated by the RDS system and comprise EON information. AF lists for cross-referenced services are normally carried in type 14A groups. Type 14A groups also comprise information about TP flags of cross-referenced services.

The type 14B groups preferably also carries information about TA flags for cross- referenced services. Type 14B groups may be transmitted only when there is a change in status of the TA flag of a referenced service, it may be transmitted continuously with a predetermined interval to facilitate appropriate information sharing with receivers and/or the like. Furthermore, type 14B groups may comprise a particular PI code for identifying a program facilitating transmitting traffic announcements. This received PI code is preferably previously stored in memory of the receiver 3. If the PI code is memorised in the receiver, then associated alternative frequencies (AFs) may also already have been noted for particular signal strength/quality.

Embodiments of a process of transmitting the interception signal 4 and a traffic bulleting signal 2 is described in relation to fig. 4.

At step S41, The warning arrangement 10 is set to broadcast the traffic bulletin signal 2 (referred to as TBS in fig. 4). The traffic bulletin signal 2 may in embodiments of the invention comprise one or more of the following information: · A TP flag set to one to enable that radio receivers consider the signal as a traffic service radio program,

• A TA flag is set to one to ensure that receivers within range of the traffic bulletin signal and tuned to receive the signal remain to be tuned to the traffic bulletin signal.

· A PI code of the traffic bulletin signal. The TA flag of the bulletin signal 2 may in embodiments be toggled between 1 and 0, e.g. with a predetermined interval, to facilitate the receivers 3 tuned to and receiving the traffic bulletin signal 2, are allowed to return to a previous program to which they were tuned before being spoofed to tune to the traffic bulletin signal by embodiments of the invention. Alternatively, the TA flag may be kept at a value of 1 and the radio receivers may automatically retune to a previous radio channel to which they were tuned before tuning/shifting to the traffic bulletin signal when being out of range of the traffic bulletin signal and/or the interception signal, because the emergency vehicle 11, or the vehicle 1, has moved away and thus no longer covers the receiver. Also the TP flag of the traffic bulletin signal 2 may be toggled in embodiments of the invention and/or may be kept at "1".

The PI code of the traffic bulletin signal 2 may be identical to all traffic bulletin devices of the system so that all warning arrangements 10 transmit the same PI code. Alternatively, the system 1 may comprise one or more warning arrangements 10 assigned with different PI codes e.g. dependent on a priority, type of emergency vehicle and/or the like. Also, in embodiments, a warning arrangement 10 adapted to be located at a stationary geographical location near roadwork- or emergency locations or the like may be assigned to a lower priority than warning arrangements 10 located in emergency vehicles 11. In embodiments, the PI codes may be the same for a group of warning arrangements while another group comprises another PI code. Thus, the warning arrangement 11 signalizes a traffic program in the form of the traffic bulletin signal 2, and the TA flag of the traffic bulletin signal, if set to one, results in the warning arrangement 11 signalizing an active traffic message.

A broadcasting channel for transmitting the traffic bulletin signal 2 is selected and the traffic bulletin signal 2 (TBS in fig. 4) is broadcasted at the channel. The selection of a channel for transmitting the traffic bulletin signal 2 may be selected in various ways. In an embodiment of the invention, the channel of the traffic bulletin signal 2 may be kept substantially fixed at a predefined channel. Alternatively, the channel of the traffic bulletin signal 2 may be varied based on a look up table and a positioning system such as a GPS (Global Positioning System), a cell phone system determining the position based on triangulation and/or any other suitable positioning system facilitating determining the position of the warning arrangement 10. Hence based on e.g. the determined position coordinates of the warning arrangement 10, a lookup table comprising channel information (e.g. PI codes, frequencies and/or the like) and coordinates or other position information specifying which channel that should be utilized in a specific area may be processed to determining a suitable radio channel for the traffic bulletin signal at the specific area that the warning arrangement is located.

In a further embodiment, the warning arrangement 10 may receive the channel for the traffic bulletin signal 2 from an external source such as an external broadcasting arrangement 6, a central handling arrangement handling and monitoring a plurality of warning arrangements and/or the like. Also, in embodiments the warning arrangement 10 may determine the channel for transmitting a traffic bulletin signal 2 by having a FM scanning arrangement scanning the FM band for a free channel for transmittance of the traffic bulletin signal. The scanning may e.g. comprise the scanning arrangement determining if any audio information configured for being transmitted to a listener is present in the M-band and/or S-band of a plurality of FM channel frequencies. Also, in the event of scanning FM channels so as to identify a suitable channel for broadcasting the traffic bulletin signal, RDS information of the scanned frequencies may also be processed, e.g. to determine pointers to radio channels configured for transmitting traffic announcements. An audio signal in the form of e.g. a siren audio signal, a prerecorded audio message, an audio signal detected by a microphone and/or the like as explained earlier is added, e.g. by modulation, to the selected channel in the S-band and/or M-band of the transmitted traffic bulletin signal.

In step S42, the Traffic bulletin signal established in Step S41 is broadcasted with a signal strength so that receivers 3 of nearby vehicles 1 will receive and broadcast the above mentioned audio content/signal of the traffic bulletin signal 2 when tuned to the radio channel of the traffic bulletin signal 2.

In step S43, the interception signal 4 is established (referred to as ICS in fig. 4). The establishment of the traffic bulletin signal 4 may be performed in different ways which are explained in more details later on in relation to e.g. figs. 5-7 as well as above in relation to e.g. fig. 2 and 3.

One or more channels for transmitting the interception signal 4 is/are selected. The selection of channels for broadcasting the interception signal 4 may be selected in different ways. For example, the warning arrangement 10 may correlate position information obtained by a positioning system, e.g. as explained above, with a lookup table to determine the channel for transmittance of the interruption signal(s) 4. In another embodiment, a scanning arrangement may be configured for continuously scanning FM radio channels in the FM band for selecting the channel(s) suitable for broadcasting the interception signal 4. In e.g. this embodiment, RDS information of radio signals from external broadcasting stations may also be processed to e.g. identify the program transmitted on the channel from an external processing arrangement 6, to identify relevant frequencies/channels in AF lists and/or the like.

The process of determining broadcasting channels for the traffic bulletin signal 2 and/or the interception signal(s) 4 may be performed continuously over time. This may be especially relevant in embodiments where the warning arrangement 10 is placed in an emergency vehicle 11, in that emergency vehicles often may move over a larger geographical area. Since the channels on which e.g. local commercial radio stations transmits their radio programs changes dependent of the geographical area, the channel of the interception signal(s) 4 and/or the traffic bulletin signal 2 may need to be adapted to the position/location of the emergency vehicle 11 so that receivers 3 of vehicles 1 originally tuned to e.g. the channels of the commercial radio stations are manipulated to automatically tune to the traffic bulletin signal 2 from the warning arrangement by means of the interception signal.

In embodiments where the warning arrangement 10 is configured for being temporarily and/or substantially permanently arranged near a road to warn drivers of approaching vehicles 1, the warning arrangement 10 may be manually and/or automatically set to a predefined radio broadcasting channel for the traffic bulletin signal 2 and one or more radio broadcasting channels for broadcasting the interception signals 4.

In step S44, the interception signal established in Step S43 is broadcasted with a signal strength so that receivers 3 of nearby vehicles 1 will receive and process the content of the information in the RDS band of the interception signal.

The signal strength of the interception signal 4 may be determined and e.g. varied in different ways. In an embodiment of the invention, the signal strength of the interception signal may be preselected to a substantially fixed value. In other embodiments of the invention, the warning arrangement 10 may comprise a scanning arrangement configured for detecting the signal strength of signals from external broadcasting arrangements 6 at the location of the warning arrangement 10 at relevant channels for transmittance of the interception signal 6. Hence, the signal strength of the interception signal may adapted/regulated (preferably automatically by the warning arrangement) based on such determined signal strengths of radio signals from external broadcasting stations to insure that the interception signal is on the one hand strong enough to ensure that nearby receivers derive the RDS information hereof and on the other hand to prevent that vehicles/receivers located at a longer distances away from the warning arrangement does not derive the RDS information. Also, in embodiments of the invention, the signal strength of the interception signal may be determined based on a positioning system and a look up table comprising a plurality of predetermined signal strengths to be utilized dependent on the location of the warning arrangement 10.

In general it is to be understood that in embodiments of the invention, the signal strength of the interception signal and/or the traffic bulletin signal may be adapted based on the local radio broadcasting environment for a given geographical area. The reason for this is that since the interception signal may be arranged for substituting RDS information broadcasted from external broadcasting arrangements with its own Information in the RDS band. Hence, the signal strength in the RDS band of the interception signal 4 may advantageously be varied to intercept the RDS band of a radio channel, and the criteria for this being successfully achieved would depend on that the energy in the RDS band of the interception signal being higher than the energy in the RDS band of the signal 5 from an external broadcasting station 6.

Different ways of manipulating the receivers 3 to automatically tune to the traffic bulletin signal 2 by means of the information in the RDS band of the interception signal 4 is explained in the following.

If a signal becomes too weak, radio receivers 3 comprising the Radio Data System facility may be adapted to tune to another channel. In the following, a method of initiating such a tuning by the interception signal 4 comprising a disturbance signal in the RDS band is described. A first indicator of a radio signal becoming too weak may be identified in the RDS sideband of a radio signal from an external broadcasting station 6 due to the very low modulation index of the RDS signal as calculated earlier. Hence, many radio receivers 3 are predetermined to seek in the AF list if the RDS signal of the signal from the external broadcasting station becomes too weak/interrupted. Based on this, in an embodiment of the invention, the information in the RDS sideband of the interception radio signal 4 transmitted from the warning arrangement 10 may comprise a noise signal modulated onto the 57±2.5kHz (and/or ±3 kHz) sidebands of the interception signal. The noise signal may e.g. comprise white noise, it may comprise grey noise and/or any other suitable signal that does not necessarily comprise RDS information but may disturb the RDS information in the signal 5 transmitted from an external broadcasting station 6. Hence, when the radio receivers 3 receives/registers this noise at the RDS side bands, the receivers 3 interpret this as the radio signal 5 from the external broadcaster 6 getting weak/interrupted and would hence automatically start to seek in the AF list for an alternate frequency to tune to. This process is described in more details in relation to fig. 5.

In step S51, one or more external broadcasting arrangements transmits RDS information at one or more predefined channels P2 that would have receivers 3 receiving and processing this RDS information to tune to the traffic bulletin signal 2 when they register a bad RDS signal This RDS information is preferably transmitted together with an audio signal of a radio station such as a commercial radio station. This RDS information may comprise channel information, comprising information of the channel frequency PI of the traffic bulletin signal 2. Furthermore, the RDS information may in embodiments comprise the PI code PI2 of the traffic bulletin signal 2. Also, the RDS information may comprise information in the form of the TP flag identifying the traffic announcement channel as a channel for transmitting channel information.

This RDS information is received, registered and stored in the receivers 3 in step S52. Preferably, the PI code and the channel frequency of the traffic bulletin signal 2 is transmitted by the external broadcasting station 6 in a way so that the when the receivers starts looking for a new channel due to a weak/interrupted RDS signal at the channel to which the receivers are tuned, the channel PI of the traffic bulletin signal is among the first, if not the first to be looked for. This may be achieved by adapting and transmitting the RDS information in a way so that that it will be stored in the AF list as one or the first channels to be looked for. In step S53, the warning arrangement 10 selects a channel for transmittance of the interception signal 4, in this case e.g. P2 at which the external broadcasting arrangement transmits a radio program and to which one or more receivers 3 are tuned.

At step S54, a noise signal is added to the interception signal in the RDS range, preferably followed up by a proper filtering so that the noise only is present within the RDS 57±2.5 kHz or (3.0 kHz) RDS range, to avoid disturbing e.g. audio signals in the M-band and/or S-band as illustrated in fig. 2. See e.g. figs 10a- lOd in relation to embodiments of adding noise to the RDS range of the interception signal.

In step S55, the interception signal 4 is transmitted from the warning arrangement 10, and in step S56, the interception signal 4 is received by nearby receivers 3 at the channel P2. The receivers 3 would now register the noise in the RDS band of the interception signal at the channel P2, but the audio signal from the external broadcaster at the channel P2 would not be disturbed due to that the interception signal 4 do not contain any detectable audio signal in the S-band and/or the M-band that would disturb the audio signal from the external broadcasting arrangement 6 from being broadcasted by the receiver 3. The receiver 3 may however, due to the noise in the RDS band of the interception signal 4, act as if the signal from the external broadcaster 6 is getting weak/disturbed, and may thus initiate seeking for an alternate frequency in e.g. the AF list. Here is to be remembered that an external broadcasting arrangement in step SI has specified the channel PI of the traffic bulletin signal 4 as being an acceptable alternate/alternative frequency, and the PI code PI2 of the traffic bulletin signal. Hence, the receivers 3 may automatically at Step S57 seek for the traffic bulletin signal 2 at channel PI, which would be present due to that the traffic bulletin signal is transmitted from the warning arrangement 10, preferably simultaneous to the transmittance of the interception signal 4. In embodiments of the invention, the traffic bulletin signal 2 at channel PI may comprise a PI code that is identical to the PI code of the radio program that the receiver was tuned to before shifting to the channel of the traffic bulletin signal. Hence, the radio receiver would see the traffic bulletin signal as a radio program that comprises the same audio signal as the radio signal that the receiver previously received.

The warning arrangement may in embodiments be adapted for transmitting a plurality of traffic bulletin signals comprising different PI codes that are identical to the PI code of the radio program that the receivers was tuned to before shifting to the traffic bulletin signal due to the information such as the noise signal in the RDS band of the interception signal. This may for example be facilitated by the warning arrangement comprising an arrangement adapted for scanning radio channels to identify the relevant PI code to add to the traffic bulletin signal(s) dependent on the radio program broadcasted at the channel that the warning arrangement is adapted to use for transmitting the interception signal. This may e.g. be performed together with identifying relevant channels for transmitting the interception signal as described in embodiments in this document, and/or by means of a look up table that may e.g. furthermore be dependent of the geographical location of the warning arrangement and/or any other suitable means.

In embodiments where a plurality of traffic bulletin signals are transmitted comprising different PI codes, the signals may be transmitted simultaneously at different channels, they may be transmitted shift wise where the PI code and the channel for transmittance may be varied, and/or the like.

Hence, the receivers may at test TE51 if an acceptable radio signal is present at the channel PI of the traffic bulletin channel, and it is in general understood that the warning arrangement 10 may be adapted so as to transmit a traffic bulletin signal 2 with a suitable strength and quality so that receivers tuned to the traffic bulletin signal 2 due to receipt of the interception signal would consider the traffic bulletin signal as an acceptable radio signal.

At test TE52, the receivers 3 perform a test to validate the PI code PI2 of the traffic bulletin signal. This will also be accepted due the external broadcasting arrangement 6 having identified the PI code PI2 of the traffic bulletin signal. Hence, the receivers 3 starts broadcasting the audio signal of the traffic bulletin signal at step S58.

When a predetermined return condition is applied with (test TE53), the receivers 3 may return to and broadcast the radio program of the previous channel (S59). The return may be performed in various ways. For example, if either the warning arrangement 10 is arranged in an emergency vehicle 11, or is arranged stationary, the receivers may automatically be arranged to tune to the previous station when the vehicles gets out of range of the traffic bulletin signal and/or the interception signal due to the vehicles driving in a direction away from the warning arrangement and/or the emergency vehicle 11 moving away from the vehicles receiving the traffic bulletin signal 2. Hence, the receivers may look in the AF list again and thus tune to the previous channel P2 since the traffic bulletin signal is no longer within range. Also, in embodiments, the traffic bulletin signal may comprise RDS information initiating the receivers to tune to the previous station. E.g. by manipulating a TA flag and/or a TP flag of the traffic bulletin signal so that a RDS receiver 3 would consider the channel as a channel transmitting traffic announcements. Hence, by toggling the TA flag and/or TP flag, e.g. with a time dependent interval, the receivers may return to the previous channel. The reason for this is that RDS receivers 3, when registering that e.g. the TA flag is not set, may return to the previous channel.

Furthermore, in embodiments, this may e.g. be combined with the interception signal 4 being stopped or manipulated in a way so that the receivers would not try to tune to the traffic bulletin signal again for a predetermined amount of time. The RDS information of the traffic bulletin signal may also in embodiments of the invention comprise information to be stored in the AF list of the receivers, and relating to which channel to return to. This may be determined by means of a look up table, e.g. combined with a positioning system as explained later on and dependent on the selected channel P2 for the interception signal. Here is to be understood that by knowing the channel P2 of the interception signal, valid channels to be returned to may be identified by e.g. a lookup table, which would eventually result in the receivers 3 tuning to a radio program that was received by the receiver before the receiver was shifted to the traffic bulletin signal.

Another way of manipulating RDS radio receivers of vehicles 1 to automatically tune to the traffic bulletin signal 2 may be adapting the interception signal 4 to comprise RDS information that would have the receivers 3 tuning to the traffic bulletin signal. Such an embodiment is described in the following in relation to fig. 6.

At Step S61, the warning arrangement 10 selects one or more radio channel(s) P2 for transmitting the interception signal 4. The selected channel P2 is preferably identical to the channel at which one or more external broadcasting arrangements 6 broadcast radio programs that the receivers 3 may be tuned to. The selection of a radio channel may for example be performed as explained in relation to fig. 4.

At step S62, RDS information comprising RDS data is added to the RDS band of the interception signal 4. The added RDS information is preferably adapted so as to utilize the EON feature of the RDS system to have the receivers 3 tune to the traffic bulletin signal 2. The RDS information of the interception signal may in embodiments comprise an identification of the broadcast channel PI of the traffic bulletin signal to e.g. be implemented in an Alternative Frequency list of the radio receivers. The RDS information of the interception signal 4 may also in embodiments comprise a RDS program identification code PI2 identical to a RDS program identification code PI2 of the traffic bulletin signal 2. Also, the RDS information of the interception signal 4 may comprise a TA flag indicating a currently active traffic announcement at the channel PI of the traffic bulletin signal 2. Likewise, the RDS information of the interception signal 4 may in embodiments comprise a TP flag set so as to indicate that the channel of the traffic bulletin signal 2 may transmit a RDS traffic announcement.

At step S63, the interception signal (ICS) is broadcasted at the channel P2 from the warning arrangement and comprising the RDS information. This signal 4 is received by nearby radio receivers 3 in step 64. The receivers 3 would now register the RDS information in the RDS band of the interception signal 4 at the channel P2, but the audio signal from the external broadcaster at the channel P2 would not be disturbed due to that the interception signal 4 do not contain any detectable audio signal in the S-band and/or the M-band that would disturb the audio signal from the external broadcaster 6. The receivers 3 may however, due to the RDS information in the RDS band of the interception signal 4 act as if the signal from the external broadcaster 6 is transmitting the information that a traffic announcement is present at the channel of the traffic bulletin signal, e.g. due to a TA flag set to "1" in the RDS information of the RDS information of the interception signal 4.

Hence, the radio receiver 3 at step S65 starts to seek for a channel transmitting the indicated traffic announcement. This channel may e.g. be identified in an AF list that has been modified by the RDS information of the interception signal to comprise the channel information and PI code PI2 of the traffic announcement signal 2.

If the receiver 3 detects a signal 2 (test TE61) from the warning arrangement 10 at the tuned channel PI, the receiver 3 proceeds at the channel PI to receive the radio signal 2, if not, it may return to the previous program at step S67.

The receiver 3 at test TE62, when tuned to the frequency PI of the traffic bulletin signal 2, may determine if a TP flag is set to one in the RDS information of the traffic bulletin signal 2. If the TP flag it is set to one, the receiver 3 proceeds, otherwise it may return to the previous program (step S67). Also, the receiver 3 may furthermore at test TE63 check if the PI code PI2 of the traffic bulletin signal 2 is identical to the PI code identified in the receiver 3 as being the PI code of a channel broadcasting traffic announcements. This may be performed by comparing the PI code of the signal 2 with a stored PI code (which may be stored in the receiver by the RDS information of the interception signal). If it is identical to the PI code received in the interception signal 4, the receiver 3 proceeds, if not, it may return to the previous program at step S67. If the PI code PI2 of the traffic bulletin signal 2 is accepted, the receiver at step S66 may start receiving the traffic bulletin information in the form of the audio signal added to the traffic bulletin signal as explained above, and/or by registering a text in a display of the radio receiver 3 determined by a RDS PTY facility of the RDS receiver. Also, the volume of the audio signal broadcasted by the receiver 3 may be automatically increased, and/or, if e.g. a CD is listened to, the audio signal of the CD may be temporarily interrupted to broadcast the audio signal of the traffic bulletin signal 2.

At test TE64, the receiver 3 may continuously tests if the TA flag of the traffic bulletin signal is set to 1, and if the receiver 5 registers that the TA flag is set to zero this indicates that the traffic bulletin from the warning arrangement 10 is over, and the receiver 3 returns to the previous station at step S67 regardless of which PI code was used by the traffic bulletin signal. Also and/or alternatively, in embodiments, the receiver 3 may automatically return to the previous channel when the traffic bulletin signal becomes to week due to increased distance between the vehicle 1 and the warning arrangement 10.

In embodiments, the interception signal 4 may comprise channel information to be stored in receivers 3 receiving the RDS information of the interception signal 4, and identifying which channel to return to after receipt and broadcast of a traffic bulletin of the traffic bulletin signal. Alternatively, the interception signal may be adapted to only manipulate the receiver so that the receiver registers the channel information, PI information and TP flag information of the traffic bulletin signal while other radio channels previously registered in an AF list of the receiver 3 are remained. Fig. 7 illustrates one embodiment comprising five radio programs providing the facility of the RDS traffic service. The radio programs P5 1, P5 2 and P5_n are ordinary radio programs with an EON feature, whereas P3 is registered to be an ordinary traffic program facilitating broadcasting ordinary traffic announcements. This is illustrated by the TP flag of P3 being set to 1 whereas the TP flag is set to 0 at P5 1, P5 2 and P5_n. Each program P5 1, P5 5 and P5_n and P3 has its own PI code, i.e. the PI code of P2 1 = lOOC, the PI code of P3= 100D, the PI code of P2 2 = 100E, and the PI code of P2_n = 100F. It is understood that these PI codes are purely examples to enhance understanding. Broadcasting arrangements 6 as the one described in relation to e.g. fig 1 in general facilitate transmitting RDS data to receivers 3 to induce these to shift to the predefined program P3 when an ordinary traffic announcement is broadcasted at P3.

To enable listeners listening to the programs P5 1, P5 2 and P5_n, to hear the traffic announcement at P3, the broadcasting arrangement 2 transmits RDS data to the receivers 3 of vehicles 1 at each of the programs P5 1, P5 2 and P5_n comprising a TA flag set to one and preferably also a PI code for the traffic program P3. This information may e.g. be transmitted at the type 14B groups which may be transmitted when there is a change in status of a TA flag.

Now, the traffic bulletin signal 2 broadcasted by the warning arrangement 10 of the present invention may be identified as PI in fig. 7. As illustrated, the traffic bulletin signal may be broadcasted at a FM radio channel (e.g. 87.5 MHz as indicated but it may be any suitable radio channel), it may have the TA flag set temporarily or continuously to one, and furthermore, the TP flag may be set to 1 so that the receivers 3 would also recognize the traffic bulletin signal 2 as a signal transmitting RDS traffic announcements as the program P3 explained above.

The following example is explained in relation to figs. 7 and 8. To allow the warning arrangement 10 to facilitate manipulating receivers 3 listening to e.g. the different radio programs P5 1, P5 2 and P5_n at different channels to tune to the channel of the traffic bulletin signal 2, the warning arrangement 10 may be configured to transmit multiple interception signals 4 1 to 4_n at the channels of P5 1, P5 2 and P5_n. Hence, different frequencies are identified as carriers for the interception signals 4, but the information added to the interception signals in the RDS band of the interception signals may be substantially similar. E.g. as described in relation to figs. 4, 5 and 6 above. This is illustrated in fig. 8. As indicated in fig. 8, the warning arrangement may transmit a plurality of interception signals 4 1 to 4_n. Also, a plurality, of broadcasting arrangements 6 may transmit radio programs at a plurality of different radio channels 5 1 to 5_n. Therefore, to have receivers 3 of different vehicles 1 tuned to the different channels P5 1 to P5_n to tune to the channel of the traffic announcement signal 2, the different interception signals 4 1 to 4_n are transmitted at different channels corresponding to the different channels P5 1 to P5_n. For example, the first interception signal 4 1 would be adapted to be transmitted at the channel of the first radio program P5 1, the second interception signal 4 2 would be adapted to be transmitted at the channel of the second radio program P5 2, and the "n" interception signal 4_n would be adapted to be broadcasted at the "n" channel P5_n of the "n" radio program. Hence, the receivers 3 of the different vehicles 1 tuned to the different stations may all be manipulated to tune to the same traffic bulletin signal 2 as described earlier in this document.

In an embodiment, the interception signal(s) may be only transmitted at each broadcast channel P5 1 to 5_n for so long time as to make receivers 3 to shift (tune) to receive the traffic bulletin. This may be controlled by e.g. transmitting the interception signal with a predetermined time interval, by transmitting the interception signal with a time interval that varies according to the transmission power of the interception signal or by any other suitable way. Also, in embodiments, only the selected frequency of the interception signal may be changed to transmit the interception signal at different channels as the RDS data may be the same.

Fig. 9 illustrates a schematic view of an example of a warning arrangement 10 according to embodiments of the invention. The warning arrangement 10 comprises an interception signal arrangement 13. This arrangement 13 may comprise one or more analogue and/or digital electronic circuits adapted for establishing the carrier of the interception signal at the selected channel. Furthermore, the interception signal arrangement 13 may comprise an RDS arrangement 13a adapted for establishing and adding information to the RDS band of the interception signal 4, e.g. as described earlier.

The RDS arrangement 13a may add RDS data to the interception signal. Alternatively, the RDS arrangement 13a may comprise noise adding means for adding a noise signal to the interception signal as described e.g. above and/or in connection with figs. 10a- lOd.

The interception signal arrangement 13 may be connected to an antenna arrangement 14 for transmitting the interception signal(s) 4. It is understood that the interception signal arrangement 13 and the antenna arrangement 14 in embodiments may be adapted to facilitate transmitting one or more interception signals. In the event that multiple interception signals are to be broadcasted at different frequencies/channels, e.g. as described in relation to figs. 7 and 8, the interception signal arrangement 13 and/or the antenna arrangement 14 may be adapted to transmit such interception signals shiftwise one at the time after each other and/or simultaneously e.g. as described above. The interception signal arrangement 13 may furthermore comprise a filter arrangement 13b for adapting the interception signal so as to reduce energy in the S- band and/or M-band of the broadcasted interception signal 4. The filter arrangement may comprise any suitable analog and/or digital filter means. Also, the filter arrangement 13b may comprise a band-pass filter, a high-pass filter and/or the like. An example of a band-pass filter may be a filter with a center frequency of 57 kHz and a bandwidth B₃dB of 2.5 kHz or 3 kHz dependent of the RDS configuration. The filter arrangement 13b may for example be adapted so that the information established by the RDS arrangement 13a is processed by the filter arrangement 13b to damp energy at frequencies in the S-band and/or M-band of the transmitted interception signal, e.g. to obtain an interception signal 4 as illustrated in fig. 3. The filter arrangement may be arranged to perform a filtering before the RDS part of the interception signal is modulated/added to the carrier and/or after the RDS part of the interception signal is modulated/added to the carrier.

The filter arrangement may furthermore comprise a filter that removes/ significantly reduces anything outside +/- 75 KHz of the interception signal to comply with a FM channel spacing of e.g. 200 kHz.

So it is to be understood that the filter arrangement 13b in embodiments may comprise a filter arrangement for removing/reducing energy in the S- and/or M band of the interception signal while keeping information in the RDS band of the interception signal, and/or a filter arrangement for removing/reducing energy outside e.g. +/- 75 KHz of the interception signal.

Also, the warning arrangement 10 comprises a traffic bulletin arrangement 15. This arrangement 15 may comprise one or more analogue and/or digital electronic circuits adapted for establishing the carrier of the traffic bulletin signal at the selected channel. Furthermore, the traffic bulletin arrangement 15 may comprise a bulletin arrangement 15a adapted for establishing and adding traffic bulletins to the of the traffic bulletin signal, e.g. as described earlier. The traffic bulletin arrangement 15 may be connected to an antenna arrangement 16 for transmitting the traffic bulletin signal 2.

The bulletin arrangement 15 may moreover in embodiments provide RDS information to the signal 2 as described in this document, for example PI codes, TA flag settings and/or the like.

It is in general to be understood that the warning arrangement may comprise a data storage arrangement 12 for storing for example audio messages to be added to the traffic bulletin signal 2. The data storage arrangement 12 may also comprise data such as look up tables, channel information, a software program product adapted for having the warning arrangement operate according to embodiments and/or combinations of embodiments as described in this document. It is to be understood that the data storage arrangement 12 may comprise one or more data storages and that the data storages may be dedicated to individual parts of the warning arrangement and/or may be shared between various arrangements such as one or more of the arrangements 13, 13 a, 15, 15 a.

Also, the warning arrangement 10 may comprise a data processor arrangement 17 connected to the data storage arrangement 12 comprising one or more data processors configured for executing a program code so that the warning arrangement 10 is operating according with one or more embodiments disclosed in this document, e.g. embodiments described In relation to figs. 1-8 and/or as specified in the claims. It is understood that the warning arrangement may in aspects comprise multiple data processors arranged to carry out different processes according to aspects of the invention. The warning arrangement 10 may furthermore in embodiments comprise a scanning arrangement 18 configured for detecting the signal strength of signals from external broadcasting arrangements at the location of the warning arrangement 10 at relevant channels for transmittance of the interception signal 6. This information may e.g. be utilized by the interception signal arrangement 13 to determine and adapt the signal strength of the interception signal(s) 4. The scanning arrangement may be connected to an antenna 19 so as to receive radio signals 5 from external broadcasting stations.

The transmissions of the interception signal(s) and/or traffic bulletin signal may in embodiments be interrupted to be able to measure the field strength of the broadcast program to be intercepted.

In embodiments, the warning arrangement 10 may comprise a channel scanning arrangement 24 configured for e.g. continuously determine a suitable channel for transmitting a traffic bulletin signal 2, e.g. by scanning the FM band within the tuneable range of receivers 3 for a free channel for transmittance of the traffic bulletin signal. Also and/or the channel scanning arrangement 24 may be configured for continuously scanning FM radio channels in the FM band for selecting the channel(s) suitable for broadcasting the interception signal 4. This may be followed up by the warning arrangement 10 analysing RDS information in radio signals at different radio channels, e.g. compared with a look up table or the like so as to e.g. identify relevant radio programs a channel that would be suitable for being utilized for transmitting the interception signal(s) and/or the traffic bulletin signal(s). The scanning arrangements 24 and 18 may in embodiments be the same arrangements, and/or it may be arrangements operating substantially independent of each other. Likewise, the scanning arrangements 24 and 18 may as illustrated be adapted with couplers, combiners and/or filters for utilizing the same antenna arrangement 19, or they may utilize different antenna arrangements. The warning arrangement 10 may further more in embodiments comprise position determination means (not illustrated) such as a position system as the Global Positioning System (GPS) arrangement, a GSM (Global System for Mobile Communications) arrangement for facilitating triangulation and/or any other suitable cellphone appliances or positioning appliances that facilitates position determination and or the like. Also a TMC decoding facility from the RDS signal of a broadcast station may be utilized to adjust to local conditions like traffic jams and/or emergencies. Such a positioning system may be implemented in various suitable ways in relation to e.g. determining suitable channels for transmitting a traffic bulletin signal 2 and/or one or more interception signals, in relation to determining the signal strength of a radio signal received from an external broadcasting station 6 and/or the like.

It is generally to be understood that a warning system according to embodiments the present invention may comprise one or multiple warning arrangements 10 according to one or more embodiments of the invention as disclosed in relation to the claims and/or the figures 1-9 and description of such figure(s).

Furthermore multiple methods as described in this document may be utilized for having receivers 3 to be tuned to or to select a traffic bulletin signal 2. For example, a warning arrangement 10 may be configured for simultaneously and/or alternatingly (with e.g. a predefined interval) broadcasting interception signals (4, 4_1, 4_2, 4_n) according to the embodiments of adding noise or RDS data to the RDS band of the interception signal as described in relation to figs. 4, 5 and/or 6.

Examples of the range(s) of the interception channel and/or traffic bulletin signal may be no more than three kilometers, such as no more than no more than 1 kilometer such as no more than 700 meters such as no more than 500 meters such as no more than 300 meters such as no more than 100 meters from the arrangement broadcasting the signal(s). Hence within this distance from the warning arrangement, the signal(s) may be properly received and processed as defined in this document. In further embodiments, the interception signal(s) and/or the traffic bulletin signal(s) may be directionally controlled, e.g. so as to achieve that more power of the signal(s) is transmitted in a forward direction (e.g. in embodiments where the signals are transmitted from an emergency vehicle) than to the sides and/or backwards in relation to the emergency vehicle. For example the radiated power in a forward/rearward ratio may be 90/10 such as 80/20 such as (70/30) such as 60/40), This may be achieved e.g. by a specific antenna configuration facilitating such directional control of the radiated signals. In embodiments of the invention, the warning arrangement may receive and process RDS information of radio signals 5 from one or more external broadcasting stations so as to e.g. identify relevant channels for transmittance of said traffic bulletin signal traffic bulletin signal and/or said interception signal. Also, In embodiments of the invention, the processing of said RDS information may comprise processing of AF list information so that the channel for transmitting said traffic bulletin signal and/or said interception signal is selected based on said processing of the AF list. E.g. by selecting a channel from the AF list with lower signal strength than other channels of the AF list at the location of the warning arrangement. In embodiments of the invention, the traffic bulletin signal and/or interception signal may hence be transmitted at a channel selected by means of the processing of said RDS information such as the AF list information. Moreover, the RDS processing may comprise identifying PI codes of the radio signal(s) 5, and a PI code of the traffic bulletin signal 2 may hence be adapted to be identical to this PI code so that a receiver accepts the traffic bulletin signal when tuning to the traffic bulletin signal 2 upon receipt of the Interception signal 4. Also, the RDS processing may comprise registering the status of the TA flag of the signal 5.

The above embodiments relating to receive and processing RDS information may be implemented by means of a RDS processing unit (not illustrated in fig. 9) of the warning arrangement 10. This RDS processing unit may hence comprise an RDS decoder arrangement and the warning arrangement 10 may hence in embodiments of the invention be adapted to receive and process the signal 5, identify the RDS information in the RDS side bands of the signal 5 and decode this information to extract RDS information regarding the AF list, PI code, AF flag and/or the like. The RDS processing unit may hence in embodiments of the invention transmit this extracted information to the traffic bulletin arrangement 15 and/or the interception signal arrangement 13 so as to facilitate an adaption of the signals 2, 4 based on the processing. Further information regarding the PI code, TA code, AF list and the like may be found above and below in relation to the description of the other figures. So hence, according to embodiment of the transmittance of the traffic bulletin signal 2 and/or the interception signal 4, 4_1 - 4_n so as to warn drivers of vehicles 1 may be adapted by receiving one or more radio signals 5 transmitted from an external broadcasting station 6, processing RDS information of said one or more radio signals 5, adapting said traffic bulletin signal 2 and/or said interception signal 4, 4 1 - 4_n based on said RDS processing, and transmitting said traffic bulletin signal 2 and/or said interception signal 4, 4 1 - 4_n to one or more receivers (3) of vehicles 1. In further embodiments, the traffic bulletin signal 2 and/or said interception signal 4, 4 1 - 4_n may hence comprises RDS data such as one or more RDS PI codes and/or TA flags, which are adapted based on the RDS processing of the signal 5. And moreover, the traffic bulletin signal 2 and/or said interception signal 4, 4 1 - 4_n may in further embodiments be transmitted at a radio channel identified by means of said RDS processing.

Figs. 10a- lOd illustrates different embodiments of a noise signal added to the interception signal(s) 4. As described above, the carrier signal 20 may be added a signal/information at the RDS frequency band (57kHz±2.5kHz) (or ±3.0 kHz), and in these embodiments, the information 25 in the Radio Data System frequency range of the interception signal comprises the noise. In a preferred embodiment of the invention, the noise signal is added to a first Radio Data System frequency side band of the interception signal 4 as illustrated in fig. 10a. This is illustrated by means of a "peak" 50 in the lower RDS frequency band 21a. This peak 50 comprises energy at one or just a few frequencies such as within 1- 20Hz, e.g. within 1-lOHz, within the (57kHz±2.5kHz) (or ±3.0 kHz) RDS frequency range. However, it might also in embodiments be a single frequency within the RDS band 21a. The other upper RDS side band 21b does in this embodiment not comprise energy in the RDS frequency range. However, it is understood that the other upper RDS side band 21b in other embodiments could comprise the noise signal 50 and that the lower sideband 21b in such an embodiment may not comprise a noise signal. The noise signal 50 in the RDS side band 21a will trigger the radio receivers to look in their AF list for an alternative frequency transmitting the same program in that the noise signal disturbs the RDS signals of the radio signal that the receivers is tuned to. Thus, receivers comprising the channel of the traffic bulletin signal 2 (not illustrated in figs lOa-lOd) in their AF lists will tune to the channel of the traffic bulletin signal.

In another embodiment, the noise signal may be added to both Radio Data System frequency side bands 21a, 21b of the interception signal 4 as illustrated in fig. 10b.

It is not necessarily important at which frequencies within the RDS frequency range that the noise signal 50 is located, but it may in advantageous embodiments of the invention be located at one or more frequencies that will cause maximum disturbance to the RDS signal.

Fig. 10c illustrates that the RDS side band of the interception signal 4 comprises a noise signal 51 in the RDS frequency range, where the frequency range of the noise signal is smaller that the frequency range of the Radio Data System frequency side band. The noise signal 51 hence comprises energy within a plurality of frequencies of the RDS signal, but does however not extend to the limit/border 22a, 23a of the of the RDS range which lies within the (57kHz±2.5kHz) (or ±3.0 kHz) as explained above. The frequency range of the noise signal 51 in this embodiment may be at least 1.5 times such as e.g. 2 times such as at least 4 times, e.g. at least 5 times such as 10 times, e.g. 20 times such as at least e.g. 50 times smaller or even smaller than the range of the Radio Data System frequency side band.

As an example of a noise signal 51 being substantially 10 at least times smaller than the frequency range of the RDS range may be that the noise signal comprises energy within 500 Hz (-2.5kHz to 2.5 kHz =5kHz, and a signal being 10 times smaller hence lies in a frequency band of 500Hz) within the 57kHz±2.5kHz RDS range.

The noise signal may hence comprise energy within a frequency range of e.g. 2.5 kHz, such as within a range of 1.25 kHz, e.g. 1 kHz, for example 500Hz, such as 250Hz or even less within the RDS frequency range. The noise signal may e.g. comprise white noise, grey noise or the like in the frequency range of the noise signal 51. Alternatively, the noise signal may comprise noise with a predefined power in the range of the noise signal. By this is understood that if the noise signal extends over e.g. 1 kHz, the power at each frequency may be substantially the same or at least predefined by determining the power of the noise signal during transmittance of the interception signal.

The noise signal may hence extend over at least 50Hz such as at least 100Hz, such as at least 500 Hz, e.g. at least 1 kHz, for example, e.g. 1.25 kHz such as at least 2.5 Khz within the RDS Range of the interception signal. In fig. 10c, it is only one of the RDS side bands of the interception signal 4 that comprises the noise signal 51. However, in further embodiments as illustrated in fig. lOd, both RDS side bands of the interception signal 4 may comprise the noise signal 51 where the noise signals 51 extends over a plurality of frequencies. In further embodiments, the noise signal 51 may extend substantially from the lower RDS border 22a to the upper RDS border 23a (and/or 22b-23b). The ratio between the power in the RDS side band comprising the noise signal 50, 51 and the other RDS side band of the interception signal 4 as e.g. in the embodiments of figs. 10a and/or 10c, may e.g. be so that one of the side bands comprises at least 5 times such as at least 10 times, e.g. at least 100 times, such as at least 1000 times more energy than the other side band of the interception signal 4.

In general, it is to be understood that the present invention is not limited to the particular examples described above but may be adapted in a multitude of varieties within the scope of the invention as specified in the claims. For example, it is to be understood that various combinations of the content of the interception signal(s), the warning signals and the establishing of these may be varied within the scope of the present invention. Also, it is understood that one or more steps as disclosed in Figs. 5 and/or 6 in embodiments of the invention may be omitted, substituted with another step, and/or the like. Also different steps of figs. 5 and 6 may be combined into further embodiments. Also, it is understood that the feature of RDS processing of the signal 5 from an external broadcasting station 6 by means of e.g. the warning arrangement 10 as described in relation to fig 9 may be combined with one or more of the described embodiments of e.g. figs. 1-8 and 10.

Claims

1. A method of warning drivers of vehicles (1), said method comprising: transmitting a traffic bulletin signal (2) at a first predefined radio channel (PI) to one or more radio receivers (3) of said vehicles (1), which one or more radio receivers (3) comprise a Radio Data System facility, and transmitting at least one further radio signal being an interception radio signal (4, 4_1, 4_2, 4_n) , wherein said interception radio signal (4, 4_1, 4_2, 4_n) comprises information (25) in the Radio Data System frequency range of a second radio channel (P2) being different from the first radio channel (PI), wherein said information is different from information in the Radio Data System frequency range of a third radio signal (5) transmitted from an external broadcasting station (6) at said second radio channel (P2), and wherein said information is configured so as to manipulate said radio receivers (3) to automatically tune said radio receivers (3) to said first radio channel (PI) to receive said traffic bulletin signal (2).

2. Method according to claim 1, wherein said interception signal (4) is configured so that radio receivers without Radio Data System facilities and receiving said interception signal (4) continue to receive and broadcast an audio signal of said third signal (5).

3. Method according to claim 1 or 2, wherein said information in the Radio Data System frequency range of said interception signal (4, 4_1, 4_2, 4_n) is configured so that radio receivers (3) with a Radio Data System Traffic Announcement facility disabled and receiving said interception signal (4, 4 1, 4 2, 4_n) continue to receive and broadcast an audio signal of said third signal (5) while other receivers (3) with the Radio Data System Traffic Announcement facility enabled and receiving said interception signal (4, 4 1, 4 2, 4_n) automatically tune to said first radio channel (PI) to receive said traffic bulletin signal (2).

4. Method according to any of the preceding claims, wherein said information in the Radio Data System frequency range of said interception signal (4, 4 1, 4 2, 4_n) is configured so that radio receivers (3) with a Radio Data System AF facility disabled and receiving said interception signal (4, 4 1, 4 2, 4_n) continue to receive and broadcast an audio signal of said third signal (5), while other receivers (3) with a Radio Data System AF enabled and receiving said interception signal (4, 4 1, 4 2, 4_n) automatically tune to said first radio channel (PI) to receive said traffic bulletin signal (2).

5. Method according to any of the preceding claims, wherein said interception signal (4, 4 1, 4 2, 4_n) is configured so that that the information of an audio signal of said third signal (5) is derivable from the output of receivers continuing to receive and broadcast an audio signal of said third signal (5) while at the same time receiving said interception signal (4, 4_1, 4_2, 4_n).

6. Method according to any of the preceding claims, wherein said interception signal (4) provides interference in the FM S-band and/or M-band of the interception signal

(4, 4 1, 4 2, 4 3) that is at least 20dB such as 30 dB for example 40dB below an audio signal of said third signal (5) registered by said receiver (3).

7. Method according to any of the preceding claims, wherein said first radio channel (PI) and said second radio channel (P2) are spaced apart in transmission frequency by at least 200 kHz.

8. A method according to any of the preceding claims, wherein said interception radio signal (4, 4 1, 4 2, 4_n) is established based on a predefined carrier frequency (20), and wherein said predefined carrier frequency (20) is modulated with said information in the Radio Data System frequency band.

9. A method according to any of the preceding claims, wherein said interception signal (4, 4_1, 4_2, 4_3) is adapted so that the energy of the carrier and eventual M- and S- signals of said transmitted interception signal is reduced compared to the un- modulated carrier.

10. A method according to any of the preceding claims, wherein a modulation index of said interception signal targeting the RDS information is preselected to a value so that the energy of a carrier of said transmitted interception signal (4, 4 1, 4 2, 4 3) is reduced while the energy in the sidebands from the RDS information in the interception signal is maintained.

11. A method according to any of the preceding claims, wherein a filter arrangement (13b) reduces and/or removes frequency components in the S-band and/or M-band of said interception signal (4, 4_1, 4_2, 4_n).

12. A method according to any of claims, wherein the relationship between energy in the Radio Data System frequency band of said transmitted interception radio signal (4, 4_1, 4_2, 4_n) and the energy at a predefined carrier frequency of said transmitted interception radio signal is at least 2: 1, e.g. at least 10: 1, such as at least 100: 1, for example at least 1000: 1.

13. A method according to any of the preceding claims, wherein the said Radio Data System frequency band of said interception radio signal (4, 4 1, 4 2, 4_n) is located substantially at 57±2.5kHz and/or 57±3.0 kHz..

14. A method according to any of the preceding claims, wherein said information (25) of said interception radio signal (4, 4_1, 4_2, 4_n) comprises a noise signal (50, 51) at said Radio Data System frequency range.

15. A method according to claim 14, wherein said noise signal (50, 51) is added to a first Radio Data System frequency side band of said interception signal (4).

16. A method according to claim 14 or 15, wherein said interception signal (4) is configured so as to contain at least 2 times such as at least 5 times, e.g. at least 10 times such as at least 100 times, e.g. at least 1000 times more energy in the one of the RDS side bands of said interception signal (4) compared to the energy in the other side band of said interception signal (4).

17. A method according to claim 14, 15 or 16, wherein said noise signal (50, 51) is added to both Radio Data System frequency side bands of said interception signal (4).

18. A method according to any of claims 14-17, wherein said noise signal (50, 51) comprises energy in a frequency range of said Radio Data System frequency side band, said frequency range of said noise signal being more narrow than the frequency range of said Radio Data System frequency side band.

19. A method according to any of claims 14-18, wherein the frequency range of said noise signal (50, 51) is at least 2 times such as at least 4 times, e.g. at least 5 times such as 10 times, e.g. 20 times smaller such as at least 100 times smaller than the range of said Radio Data System frequency side band.

20. A method according to any of claims 14-19, wherein the noise signal (51) extends over a frequency range of at least 50Hz such as at least 100Hz, e.g. as at least 500 Hz, such as at least 1 kHz, for example, e.g. 1.25 kHz such as at least 2.5 KHz within the RDS frequency Range of said interception signal (4).

21. A method according to any of claims 14-20, wherein said noise signal (50) extends over no more than 5 Hz within the RDS frequency Range of said interception signal (4).

22. A method according to any of the preceding claims, wherein one or more stationary broadcasting stations (6) transmits channel information and/or a RDS Program Identification code (PI2) of said traffic bulletin signal (2) to said radio receivers (3) so as to enable said receivers (3) to automatically tune to said traffic bulletin signal (2) when receiving said interception radio signal (4, 4_1, 4_2, 4_n).

23. A method according to any of the preceding claims, wherein said information (25) of the interception radio signal (4, 4 1, 4 2, 4_n) comprises Radio Data System data.

24. A method according to any of the preceding claims, wherein said interception signal (4, 4 1, 4 2, 4_n) comprises Enhanced Other Network data of the RDS system.

25. A method according to any of the preceding claims, wherein said interception signal (4, 4_1, 4_2, 4_n) comprises EON data configured so that receivers (3) with RDS traffic announcement features in EON enabled will tune to said first predefined radio channel (PI), and wherein receivers (3) with RDS traffic announcement features in EON disabled will stay tuned to said second channel (P2).

26. A method according to any of claims 23-25, wherein said Radio Data System data comprises an identification of the broadcast channel (PI) of said traffic bulletin signal (2) to be implemented in an Alternative Frequency list of said radio receivers

27. A method according to any of claims 23-26, wherein said Radio Data System data comprises a program identification code (PI2) of said traffic bulletin signal (2).

28. A method according to any of claims 23-27, wherein said Radio Data System data comprises a TA flag and/or other EON features indicating a currently active traffic announcement.

29. A method according to any of claims 23-28, wherein said Radio Data System data comprises a RDS TP flag set so as to indicate that said traffic bulletin signal (4, 4 1, 4 2, 4_n) is considered as transmitting a traffic announcement.

30. A method according to any of the preceding claims, wherein said traffic bulletin signal comprises RDS data to be received and processed by said receivers.

31. A method according to any of the preceding claims, wherein said traffic bulletin signal comprises a RDS traffic program flag (TP) set so as to enable that said one or more radio receivers consider the traffic bulletin signal (2) as a traffic service signal, and/or a traffic program flag (TA) set so as to ensure that said one or more receivers tuned to receive the traffic bulletin signal remain to be tuned to the said traffic bulletin signal.

32. A method according to any of the preceding claims, wherein said traffic bulletin signal comprises a RDS PI code (PI2), and wherein a RDS PI code identical to the

RDS PI code (PI2) of the traffic bulletin signal is stored in said receiver(s) (3) so that the receiver(s) (3), when tuning to the traffic bulletin signal (2) accepts the PI code (PI2) of the traffic bulletin signal (2).

33. A method according to any of the preceding claims, wherein a PI code (PI2) of the traffic bulletin signal is stored in the receiver (3) by means of RDS information in radio signals from an external broadcasting arrangement (6) and/or by means of RDS data in the interception signal (4, 4_1, 4_2, 4_n).

34. A method according to any of the preceding claims, said method comprising that scanning means (24) scan the FM frequency band within the tunable range of said receivers (3) for one or more channels to be utilized for broadcasting said interception signal (4, 4_1, 4_2,4 _n) and/or said traffic bulletin signal.

35. A method according to any of the preceding claims, said method comprising the step of at the location from where the interception signal is transmitted detecting the signal strength of a signal (5 1, 5 2, 5_n) from an external broadcasting arrangements (6) at said second channel (P2), and wherein the signal strength of said interception signal (4, 4_1, 4_2, 4_n) and/or traffic bulletin signal (2) is adapted based on this scanning.

36. A method according to any of the preceding claims, wherein a plurality of interception signals (4 1, 4 2, 4_n) are transmitted at different channels.

37. A method according to any of the preceding claims, wherein said traffic announcement signal (4) and/or said interception signal (4, 4_1, 4_2, 4_n) are transmitted from a vehicle such as an emergency vehicle (11).

38. A method according to any of the preceding claims, wherein said traffic bulletin signal(s) and said interception signal(s) are transmitted from a stationary location.

39. A method according to any of the preceding claims, comprising a positioning arrangement detecting a geographical position and adjusting the channel for transmittance of said interception signal (4, 4 1, 4 2, 4_n) and/or traffic bulletin signal (2) based thereon.

40. A method according to any of the preceding claims, comprising a TCM decoding.

41. A method according to any of the preceding claims, comprising the steps of receiving and processing RDS information of radio signals (5) from one or more external broadcasting stations (6) e.g. so as to identify relevant channels (PI, P2) for transmittance of said traffic bulletin signal traffic bulletin signal (2) and/or said interception signal (4, 4_1 - 4_n).

42. A method according to claim 41, wherein said processing of said RDS information comprises processing AF list information of said RDS information, and wherein a channel (PI, P2) for transmitting said traffic bulletin signal (2) and/or said interception signal (4, 4 1 - 4_n) is selected based on said processing.

43. A method according to claim 41 or 42, wherein said traffic bulletin signal (2) and/or said interception signal (4, 4 1 - 4_n) is transmitted at a channel selected by means of said processing of said RDS information.

44. A method according to any of claims 41-43, comprising the steps of receiving and processing RDS information of one or more radio signals (5) from one or more external broadcasting stations (6) so as to identify one or more RDS PI codes of said radio signals, and wherein a PI code of said traffic bulletin signal (2) is adapted based on said identified PI codes.

45. A method according to claim 41-44, comprising the steps of receiving and processing RDS information of one or more radio signals (5) from one or more external broadcasting stations (6) so as to identify the status of a TA flag of said one or more radio signals.

46. A warning system for warning drivers of vehicles (1), said system comprising: a plurality of radio receivers (3) arranged at said vehicles (1), which radio receivers comprise a Radio Data System facility, and one or more stationary broadcasting stations (6) configured for transmitting radio signals (5) at one or more predefined radio frequencies to one or more radio receivers (3) of, said vehicles (1), and a broadcasting arrangement (10), said broadcasting arrangement (10) being configured for:

transmitting a traffic bulletin signal (2) at a first predefined radio channel (PI) to one or more radio receivers (3) of said vehicles (1), which one or more radio receivers (3) comprise a Radio Data System facility, and transmitting at least one further radio signal being an interception radio signal (4, 4_1, 4_2, 4_n) , wherein said interception radio signal (4, 4_1, 4_2, 4_n) comprises information (25) in the Radio Data System frequency range of a second radio channel (P2) being different from the first radio channel (PI), wherein said information is configured so as to manipulate said radio receivers (3) to automatically tune said radio receivers (3) to said first radio channel (PI) to receive said traffic bulletin signal (2).

47. A warning system according to claim 46 configured for operating in accordance with a method according to one or more of the claims 1-45.

48. A warning arrangement (10) for warning drivers of vehicles (1), said warning arrangement (10) being configured for: transmitting a traffic bulletin signal (2) at a first predefined radio channel (PI) to one or more radio receivers (3) of said vehicles (1), which one or more radio receivers (3) comprise a Radio Data System facility, and transmitting at least one further radio signal being an interception radio signal (4, 4_1, 4_2, 4_n) , wherein said interception radio signal (4, 4_1, 4_2, 4_n) comprises information (25) in the Radio Data System frequency range of a second radio channel (P2) being different from the first radio channel (PI), wherein said information (25) is configured so as to manipulate said radio receivers (3) to automatically tune said radio receivers (3) from a third radio signal (5) broadcasted from an external, stationary broadcasting station (6) at said second channel (P2) to said first radio channel (PI) to receive said traffic bulletin signal (2).

49. A warning arrangement (10) according to claim 48 configured for operating in accordance with a method according to one or more of the claims 1-45 and/or a system according to any of claims 46-47.

50. A method of adapting transmittance of a traffic bulletin signal (2) and/or an interception signal (4, 4 1 - 4_n) so as to warn drivers of vehicles (1), said method comprising the steps of: receiving one or more radio signals (5) transmitted from an external broadcasting station (6), processing RDS information of said one or more radio signals (5), adapting said traffic bulletin signal (2) and/or an interception signal (4, 4 1 - 4_n) based on said RDS processing, and transmitting said traffic bulletin signal (2) and/or said interception signal (4, 4 1 - 4_n) to one or more receivers (3) of vehicles (1).

51. A method according to claim 50, wherein said traffic bulletin signal (2) and/or said interception signal (4, 4 1 - 4_n) comprises RDS data such as one or more RDS PI codes, TA flags, which are adapted based on said RDS processing.

52. A method according to claim 50 or 51, wherein said traffic bulletin signal (2) and/or said interception signal (4, 4 1 - 4_n) are transmitted at a radio channel identified by means of said RDS processing.

53. A method according to any of claims 50-52, further comprising the steps of transmitting said traffic bulletin signal (2) at a first predefined radio channel (PI) to one or more of said radio receivers (3) of said vehicles (1), transmitting at least one further radio signal being said interception radio signal (4, 4_1, 4_2, 4_n) , wherein said interception radio signal (4, 4_1, 4_2, 4_n) comprises information (25) in the Radio Data System frequency range of a second radio channel (P2) being different from the first radio channel (PI), wherein said information is different from information in the Radio Data System frequency range of a third radio signal (5) transmitted from an external broadcasting station (6) at said second radio channel (P2), and wherein said information is configured so as to manipulate said radio receivers (3) to automatically tune said radio receivers (3) to said first radio channel (PI) to receive said traffic bulletin signal (2).

54. A method according to claim 53, comprising one or more of the steps of one or more of the claims 2-45.

55. A method according to any of claims 50-54, wherein said traffic bulletin signal (2) and/or said interception signal (4, 4 1 - 4_n) is transmitted from a vehicle such as an emergency vehicle.