WO1991008622A1 - Dual satellite navigation method and system - Google Patents
Dual satellite navigation method and system Download PDFInfo
- Publication number
- WO1991008622A1 WO1991008622A1 PCT/US1990/007005 US9007005W WO9108622A1 WO 1991008622 A1 WO1991008622 A1 WO 1991008622A1 US 9007005 W US9007005 W US 9007005W WO 9108622 A1 WO9108622 A1 WO 9108622A1
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- WIPO (PCT)
- Prior art keywords
- signal
- satellite
- objed
- fixed station
- satellites
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/46—Indirect determination of position data
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/87—Combinations of radar systems, e.g. primary radar and secondary radar
- G01S13/876—Combination of several spaced transponders or reflectors of known location for determining the position of a receiver
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
- G01S5/14—Determining absolute distances from a plurality of spaced points of known location
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/46—Indirect determination of position data
- G01S2013/466—Indirect determination of position data by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
Definitions
- This invention relates to object position determination using satellites. More specifically, this invention relates to a novel and improved method and system for mobile vehicle position determination using signal propagation time delays through a plurality of communication paths to calculate the vehicle position.
- One industry in particular in which such information is particularly desirable is the commercial trucking industry.
- an efficient and accurate method of vehicle position determination is in demand.
- the trucking company home base obtains several advantages.
- the trucking company can keep the customer apprised of location, route and estimated time arrival of payloads.
- the trucking company can also use vehicle location information together with empirical data on the effectiveness of routing, thereby determining the most economically efficient routing paths and procedures.
- truck location information has been communicated to the trucking company home base by the truck drivers themselves, via telephones, as they reach destinations and stopovers.
- These location reports are intermittent at best, because they only occur when the truck driver has reached the destination or stopover and can take the time to phone the trucking company home base.
- These location reports are also quite costly to the trucking company because in effect they cause substantial down time of the freight carrying vehicle. This down time is due to the fact that to make a location report, the tractor driver must remove his vehicle from route, find a telephone which he can use to phone the home base, and take the time to make the location report.
- This method of location report also leaves room for substantial inaccuracies. For example, truck drivers may report incorrect location information either mistakenly or intentionally; or report inaccurate estimates of times of arrival and departure.
- the commercial trucking industry is implementing versatile mobile communication terminals for use in their freight hauling tractors.
- These terminals are capable of providing two-way communications between the trucking company home base and the truck.
- the communications are via satellite between the truck and a network communications center or hub.
- the trucking company is coupled by conventional means, such as telephone lines to the hub.
- Using the radio communication capabilities at each mobile terminal to provide vehicle position determination offers great advantages to the commercial trucking industry. Location reports would no longer be intermittent because the trucking company home base could locate a vehicle at will. No down time of the freight hauling vehicle would be required because the communications necessary for determining location could take place while the truck is in route.
- each mobile unit includes a LORAN-C unit which typically includes an antenna and position sensor/processor.
- the LORAN-C signals are received at the mobile unit where they are processed.
- the resulting position determination may then be transmitted to the fixed station.
- the present invention is a method of object position determination which relies upon the theory of trilateration.
- Trilateration prescribes that if the position of three objects are known relative to each other, and the distance from each of these three objects to a fourth object is known, then the three dimensional position of the fourth object can be determined within the coordinate frame which described the location of the first three objects.
- the present invention employs trilateration by first assigning one of the three fixed object locations to the center of the earth. Because the object whose position is to be determined, typically a vehicle, is known to travel upon the surface of the earth, standard geodetic planetary models are available to define the distance from the earth's center to any latitude and longitude location on the surface.
- the second and third object locations are given by two earth orbiting, repeater satellites, whose positions in earth coordinates, if not known are then ascertained.
- the distance from each of these satellites to the object whose position is to be determined is then ascertained.
- the three dimensional position of the object is determined and translated onto the latitude and longitude lines of the earth.
- the method of the present invention can be used to initially determine the positions of the two earth orbiting satellites within the earth coordinate frame using trilateration. As discussed, these satellites can be located in earth coordinates if the distance from the satellites to three fixed positions is known.
- These three fixed positions are three fixed observing sites positioned upon the surface of the earth, whose positions are known precisely in earth coordinates, and have identical communications means as do the vehicles.
- the distances from the satellites to these fixed observing sites are determined by ascertaining propagation times of the radio signals transmitted to and from these stations via the satellites. From these propagation times, the distance over which those signals have traversed can be computed. Once these distances are determined, the respective satellites positions, in earth coordinates, may be calculated.
- the method of the present invention is used primarily to determine the position of an object on the surface of the earth.
- the distance from each of the two satellites to the object position is determined. Again, distances are computed based upon radio signal propagation times over which that signal has traversed.
- a fixed ground station continuously transmits two radio signals, each with an identical periodic carrier modulation, via each of the satellites to the object being located.
- the object is typically a mobile unit or vehicle having a communications terminal.
- the fixed ground station signals, as transmitted to the object are referred to herein as forward signals.
- the object continuously receives these periodic forward signals and measures the percent of periodic phase offset between the two carrier waveforms.
- the difference in phase between these two carrier waveforms is due to one of the signals traveling a longer path length via one satellite than the other.
- the object transmits a return signal, after some arbitrary delay in which the amount the delay is not important nor required to be known, containing the percent offset information.
- the return signal is transmitted upon the same path as the forward signal from the first satellite, back to the fixed ground station.
- the object performs functions that slave the clock standard of the object to the reception of the periodic signal.
- the object clock standard is offset in time from the fixed ground station transmitted signal on account of the signal propagation delay.
- the object is then allowed to transmit the observed percent offset between the two forward signals, starting at some specific period in the future.
- the fixed ground station then receives the return signal back through the first satellite whenever it comes back, but realizes the receipt of a message starting with that specific period identification number, or frame, has arrived later than the current period being sent out on the forward carriers.
- the amount of this late arrival is interpreted as the instantaneous round trip delay of signals traveling a path from the fixed ground station to the object and back, through the first satellite.
- the forward signal propagation delay changes as the object changes position.
- the object clock standard since the object clock standard is slaved to the received forward signal, the object clock standard changes as does the propagation delay. Therefore, position determination functions to be performed by the object at some arbitrary time in the future are not hampered even though the object has moved since the request was sent to the object. The object merely needs to make a timely measurement of the offset in the two periodic signals just prior to transmitting to the fixed ground station the corresponding data.
- the forward signal is not marked by any operation at the fixed ground station just prior to transmission as it leaves the fixed ground station; nor when it arrives at the object; nor just prior to transmission of a return signal by the object.
- the phase offset between the two forward signals as received by the object is also not marked against any known absolute time reference or dock, since it is only determined against the object local dock which is continuously slaved to the motion of the vehide, and the motion of the satellite in space.
- the fixed station only makes comparisons of an agile fixed ground station reception dock time against the current, fixed ground station transmission dod time to produce the round trip delay.
- the method of the present invention determines the distance from each of the satellites to the object whose position is to be determined.
- a mobile communications terminal serves as the receiver and transmitter of the objed whose position is to be determined.
- a fixed ground station is in communications with the mobile communications terminal via a primary satellite.
- the trucking company home base is capable of communicating with the ground station to complete communications with the mobile communications terminal. Typically it is the trucking company home base that initiates a vehide position determination. However, the mobile communications terminal itself may initiate a position determination.
- the present invention provides for earth vehicle position determination from values derived from signal propagation delays. Values corresponding to a round trip propagation of a signal communicated through a transponder of a first satellite and a propagation delay difference of one way signals communicated through the first satellite transponder and transponder of a second satellite are generated and used in computing vehide position.
- the round trip delay is computed implidtly by comparison of the current time of the fixed station transmission dodc with the time of the fixed station reception clock upon receipt of the relevant return path transmissions from the vehide.
- the vehicle local time clock is slaved diredly to the reception of a forward link transmission from the fixed station and thus indudes an inherent propagation delay with respect to the current time at the fixed station transmission dodc.
- the vehicle return transmissions are transmitted according to normal communication methods of TDMA assignments on the return channels.
- the return dock is allowed to dynamically adjust in real time to demodulate with highest probability any return link transmission from many vehide communication transmissions.
- the time differential is computed as a function of phase offset in periodic modulation of the received signals.
- the location of different vehicles in different user groups may be determined.
- Various arrangements of primary and secondary satellite transponders can be utilized to fadlitate communication and location of vehicles in differing user groups.
- the use of two satellites fadlitate a round trip signal propagation value and a propagation time differential value to be generated. From these values and other known position and distance values, vehide position can be determined.
- Figure 1 is an illustration of an exemplary embodiment of the trilateration method of the present invention in which the major components used for objed location are identified;
- Figure 2 is an illustration of the components and signal paths used in the method of the present invention to determine the distance between satellites and the objed whose position is to be determined;
- Figure 3 is an illustration of an exemplary embodiment of the present invention in which the major components used for satellite location are identified;
- Figure 4 is an illustration of the components and signal paths used in the method of the present invention to determine the distance between a fixed ground station and the satellites, and between other fixed observing sites and the satellites;
- Figure 5 is an exemplary illustration of the waveform of the first and second forward carrier signals as they may be received at the objed whose position is to be determined, or other fixed communication terminals used for satellite location purposes;
- Figure 6 is a graph illustrating the fixed ground station time references and mobile unit time reference;
- Figure 7 is an exemplary illustration of a two satellite, four transponder communication and position determination system.
- Figure 8 is an exemplary illustration of a two satellite, three transponder communication and position determination system. DETAILED DESCRIPTION OF THE PREFERRED
- a hub or fixed ground station 10 in Figure 1 indudes a communications terminal 10a which is capable of satellite communications.
- Terminal 10a typically indudes a transceiver, an interface to the customer home base and a processor each (not shown).
- Fixed station 10 also indudes primary antenna 10b and secondary antenna lOc.
- Primary antenna 10b is in line of sight with primary satellite SI and is capable of tracking satellite SI. Transmissions on primary antenna 10b typically contain digital information modulated on a signal carrier.
- the signal carrier is characterized as an RF signal with sawtooth periodic frequency modulation.
- Secondary antenna 10c is in line of sight with secondary satellite S2 and is capable of tracking satellite S2. Transmissions on secondary antenna 10c typically consist of the signal carrier lacking the digital information modulation although the sawtooth periodic modulation remains.
- Primary satellite SI is an earth orbiting satellite carrying a standard transponder payload and is positioned in geosynchronous orbit above the earth in line of sight of both fixed station 10 and the objed to be located, objed 12.
- the secondary satellite S2 is also an earth orbiting satellite carrying a standard transponder payload and is positioned in geosynchronous orbit above the earth in line of sight of fixed station 10 and objed 12. It is preferred that satellites SI and S2 have an angular separation in the range of 8°- 24° although angles as low as 3° and as high as 70° are possible.
- Mobile unit 12 is a typical commercial trucking vehicle having a mobile communications terminal 14 mounted in the tractor or cab of the vehicle.
- Mobile communications terminal 14 includes antenna 16 and is capable of tracking satellites SI and S2.
- Mobile communications terminal 14 is capable of respectively transmitting and receiving communication signals to and from satellite SI, while typically only receiving signals from satellite S2.
- the primary function of the method of the present invention is determining the position of a vehide. This is accomplished by solving a set of non-linear equations. These equations contain the unknown vehide position components, in cartesian x-y-z coordinates, on one side of the equation set, and observed (or measured) distance values on the other side. Each of the lengths LI, L2 and L3 are defined according to a distance function. Hence, the model for each length is the sum of the squares of differences in the three cartesian components, x-y-z, where:
- the method of the present invention provides for the measuring of tiie satellite cartesian coordinates xV-yV-zV.
- the three unknowns, xV-yV-zV on the right hand side are expressed in three unique ways by three expressions.
- three actual values are assigned to these expressions.
- the left side distance values (except 13) are obtained through a measuring process as defined herein as a part of the method of the present invention.
- the distance value L3 is simply assigned the value of the earth's radius, i.e., from the earth's center to the vehide position which is approximately 6,378,137 meters.
- Satellite position information may be obtained from satellite controllers. However, more current information on satellite position may be obtained through a reverse process of trilaterating the satellites from a plurality of fixed observing sites whose cartesian x-y-z coordinates are known. The process of determining satellite position is described later herein with reference to Figures 3 and 4. Determination of the distance between the satellites and the vehide whose position is to be determined is accomplished by translating radio signal propagation times into distance through which that signal has traversed. As shown in Figure 2, forward signals are transmitted from station 10, at antennas 10b and 10c, via primary satellite SI and secondary satellite S2 respectively to mobile unit 12.
- the signal transmitted from antenna 10b via satellite SI to mobile unit 12 is identified as the forward link signal 20 with the uplink and downlink portions thereof being respectively identified by the reference numerals 20a and 20b.
- the signal transmitted from antenna 10c via satellite S2 to mobile unit 12 is identified as the forward link signal 22 with the uplink and downlink portions thereof being respectively identified by the reference numerals 22a and 22b.
- the signal carrier waveforms of forward link signals 20 and 22 are identical and synchronized when generated for transmission.
- a forward link clock is used in generating the periodic sawtooth frequency modulation carrier of the forward link signals.
- the satellite transponder through which this signal is relayed may be operated at a significantly lower power.
- the transponder power level may be only 10% of a 10 KW transponder to support an unmodulated carrier and still provide an adequate ranging signal.
- mobile communications terminal 14 receives upon antenna 16 forward link signals 20 and 22.
- the periodic modulation for both these signals is shown in Figure 5.
- Mobile communications terminal 14 measures the percent phase offset, with respect to the forward link signal period, in the sawtooth periodic modulation of the carrier signals arriving from the two forward link signals 20 and 22.
- Phase offset can be measured using either independent match filtering on both signals and comparing time differentials between them, or mixing the two signals together and deriving the time differential from the phase of the resulting signal.
- the measured percent phase offset will be interpreted as a time difference, DT, of absolute times T2 and Tl which are not available at mobile unit 12 since the time base within mobile unit 12 is slaved to receiving the periodic modulation via satellite SI and is subject to location of the vehide on the earth and/or to the satellite motion about its nominal location in space.
- Mobile communications terminal 14 is capable of transmitting a return link signal 24 via primary satellite SI to fixed station 10.
- Return link signal 24 is comprised of uplink and downlink signal portions identified respectively by the reference numerals 24a and 24b.
- mobile communications terminal 14 In mobile unit 12, specialized algorithms are utilized by mobile communications terminal 14 for acquiring and tracking satellite relayed signals. These algorithms are used to sequentially acquire and track the periodic modulation of the satellite forward link signals to permit phase offset measurements to be made. Typically the mobile unit directional antenna is tracking the primary satellite signal, but to make the phase offset measurement the antenna is rotated in azimuth to locate the secondary satellite signal. Mobile communications terminal 14 frequency plan and match filter time is adjusted to receive the forward link signal transmitted through the secondary satellite. Once the secondary satellite signal is acquired and tracked precisely, the antenna is rotated back in azimuth for acquisition and tracking of the primary satellite relayed signal at which time the mobile unit measures the phase offset.
- Return link signal 24 carries information including information indicative of the time difference between forward link signals 20 and 22 at mobile unit 12, i.e. DT.
- the time difference DT is monitored and noted at mobile unit 12 immediately prior to transmission of return link signal 24.
- communications terminal 10a Upon reception of return signal 24 at fixed station 10, communications terminal 10a measures the required dock offset in the return link hardware to receive the return transmission and successfully demodulate its information.
- This clock offset of the return link clock relative to the forward link clock, the forward link clock used in generating the sawtooth periodic modulation shown in Figure 5, is marked as the instantaneous RTD (round trip delay).
- the reference clock of mobile unit 12 is slaved to the received forward link periodic carrier waveform. Since the forward link signal undergoes a propagation delay between transmission and reception, the reference clock of mobile unit 12 is delayed with respect to the transmitted forward link periodic carrier by this propagation delay.
- the periodic carrier waveform transmitted by fixed station 10 contains information.
- Mobile unit 12 thus synchronizes its timing to the received signal to demodulate this information from the carrier.
- TDMA Time Division Multiple Access
- fixed station 10 may command mobile unit 12 to immediately initiate position determination steps or at some future time. Whenever mobile unit 12 reference dock is in synchronization with the received forward link periodic carrier waveform, valid position determination steps can be executed.
- Figure 6 illustrates in graphical form the relative reference dock offsets at fixed station 10 and mobile unit 12.
- Fixed station 10 transmits data in frames with the transmit reference dock timing frames illustrated in the top frame line.
- One or more frames for example frame 051, contains a command that is sent to mobile unit 12 to begin transmitting data corresponding to the time difference DT to fixed station 10 at a certain frame, for example frame 103.
- frame 103 contains a command that is sent to mobile unit 12 to begin transmitting data corresponding to the time difference DT to fixed station 10 at a certain frame, for example frame 103.
- fixed station 10 would expect to receive mobile unit 12 transmitted data in frame 103, absent any propagation delays, with interpretation of the data as a return during the frame.
- Mobile unit 12 receives the command at frame 051 which as received is delayed in time with resped to the fixed station transmit reference by the forward link propagation delay FLD.
- the command is interpreted with the time difference DT being determined just prior to transmission of this data in frame 103.
- the data is transmitted back to fixed station 10. The delay in transmission with resped to the transmit reference dock of fixed station 10 is equal to the FLD.
- the return link signal in the preferred embodiment is a spread spectrum modulated signal.
- the spread spectrum modulation has a minimiim pseudorandom (PN) chip rate modulation of 1 MHz.
- PN pseudorandom
- a short period, pseudorandom, maximal length code, period 63, is used for quick detection of the return link signal preamble.
- the remaining message transmission is modulated with each length-63 period modulated with an additional pseudorandom, maximal length sequence with period 31.
- Combining the 63-length sequence with 31-length overlay sequence produces a period of length 1953 chips long. This length in microseconds allows for an unambiguous alignment of the return link signal demodulator hop edge to less than 10% of a spread spectrum chip and thus precise measurement of the round trip delay on the order of 0.1 microseconds.
- the signal transmitted from mobile unit 12 to fixed station 10 also undergoes a return link propagation delay RLD.
- the RLD is equal to the FLD, with slight corrections, since the signals traverse the same path.
- the receive dodc of fixed station 10 is offset in timing with resped to the transmit reference dock to account for propagation delays. This offset in timing is a round trip delay RTD whidi equals the FLD added to the RLD.
- Fixed station 10 receive clock timing is offset in order to properly demodulate frame data.
- Fixed station 10 receives in frame 103, according to the receive reference dock timing, mobile unit 12 transmitted DT data.
- Several bits of information are collected as frames are demodulated and tracked by the fixed station receiving equipment.
- a dedsion is made that tracking is settled and a determination of RTD is made and recorded at the fixed station 10.
- tracking is settled at during frame 105 of the fixed station receive reference clock timing.
- a determination of propagation delay is then made by comparing the receive reference dock with the current transmit reference dock.
- the transmit reference clock is ending frame 107 and beginning frame 108 when the RTD is interpreted against the receive dock in the middle of frame 105. This 2 1/2 frame offset is readily computed into a RTD since each frame is a known quantity of time.
- Dividing round trip propagation time value RTD in half yields a value FLl which corresponds to the propagation time of forward link signal 20, i.e.
- the values FLl and FL2, corresponding to the propagation times of forward link signals 20 and 22, are then multiplied by the value corresponding to the propagation velodty of an electromagnetic signal in free space. This multiplication process yields the propagation distance of forward link signals 20 and 22 respectively.
- FLl and FL2 are then used to determine single leg distances between satellites SI and S2 toward the mobile unit 12.
- the present invention provides for the measuring of the distances from fixed station 10 to the satellites or using distance values obtained from satellite control operations.
- the distances from fixed station 10 to satellites SI and S2 are respectively identified by the distance values Dl and D2.
- the distances from satellites SI and S2 to mobile unit 12 are respectively identified by the distance values LI and L2.
- the distance values LI and L2 are calculated by subtracting the distance values Dl and D2 from the signal propagation paths 20 and 22 respedively.
- the distances may be computed from the following equations:
- the cartesian x-y-z coordinate system is most conveniently referenced relative to the center of the earth.
- the positions of primary and secondary satellites are determined in much the same manner as the position of the mobile unit. In essence, the distance from these satellites to at least three geometrically diverse but known positions are measured to yield the positions of the satellites.
- Located at the three geometrically diverse sites are fixed communication terminals whose positions are known accurately in the earth-fixed coordinate frame. The distance from each of these sites to each of the satellites is measured by the same means of RTD and DT combinations with the additional requirement that one of the fixed communications terminals collocated with Hub station 10 so that the common link distance between station 10 and each satellite can be removed from the forward link distance to each of the other fixed observation sites.
- the velodty of the satellite must also be estimated so that satellite position may be extrapolated accurately to any arbitrary time point, espedally future time points. Without accurate extrapolation, the performance of the mobile unit navigation function suffers.
- the "best" way, in a minimum variance estimate sense, to perform extrapolations of position from the information contained in the tracking data is to estimate position and velodty simultaneously in a sequential filtering scheme, such as a Kalman filter.
- a sequential filtering scheme such as a Kalman filter.
- Kalman filtering techniques are well known in the art.
- the Kalman filtering approach has the advantage that tracking data need not occur simultaneously in time and that it can be processed one-at-a-time. When each new observation is available, it can be folded into a new position/ velocity estimate whidi reflects the best current estimate of the satellite from all the data and it is not necessary to wait for three such reports.
- the filter then has a minimum of 6 states, three position states and three velodty states. By adding three acceleration states to the filter the tracking behavior improves substantially for motion that is in fad, due to an orbit.
- the filter also tracks nonorbital motions, which will occur when station adjustments are made with the satellite's maneuvering rockets.
- Kalman filtering techniques can therefore be used to convert the fixed location RTDs and DTs from fixed tracking sites, into satellite locations in real time using sequential time reports at predetermined intervals from the fixed tracking sites. For example, a first fixed tracking site reports in and is followed a minute later by a next fixed tracking site and so on.
- Figure 3 depicts the components used in the preferred embodiment of the present invention to determine the position of satellites SI and S2.
- Figure 3 shows three fixed observing sites, fixed station 10 and fixed units 30, 32 and 34 which may be mobile units positioned at known fixed observing sites or locations.
- Fixed station 10 as discussed previously is comprised of communications terminal 10a, primary antenna 10b and secondary antenna 10c.
- Fixed mobile unit 30 is comprised of communications terminal or transceiver 30a and antenna 30b.
- fixed mobile units 32 and 34 are respectively comprised of communications terminals or transceivers 32a and 34a, and respectively corresponding antennas 32b and 34b.
- satellite SI is the first satellite whose position is to be determined. Satellite SI orbits the earth and at the time of position determination is in line of sight of the fixed observing sites, i.e. fixed station 10 and fixed mobile units 30, 32 and 34.
- Figure 4 illustrates the signals used in measuring the distance between fixed station 10 and primary satellite SI.
- one fixed observing site, fixed mobile unit 30, is collocated with fixed station 10.
- the distance Dl between fixed station 10 and satellite SI is the same as the distance Dl' between mobile unit 30 and satellite SI, i.e.
- Fixed station 10 transmits from primary antenna 10b a forward link timing signal 40, comprised of uplink portion 40a and downlink portions 40b and 40c.
- Forward link signal 40 is transmitted from antenna 10b (uplink portion 40a) via primary satellite SI to fixed mobile unit 30 located at the fixed observing site immediately adjacent fixed station 10 (downlink portion 40b).
- Forward link signal 40 is also transmitted by antenna 10b via satellite SI to fixed mobile unit 32, uplink portion 40a and downlink portion 40c.
- fixed mobile unit 30 Upon reception of this forward link signal 40 at fixed mobile unit 30, fixed mobile unit 30 transmits a return link signal 42, comprised of uplink portion 42a and downlink portion 42b, via primary satellite SI to fixed station 10.
- the RTD due to the signal path combination of 40 and 42 is measured.
- the resulting RTD value is divided by four to yield the propagation time of a radio signal traversing a path from fixed station 10 to primary satellite SI.
- the round trip propagation time value RTD divided in half results in the value which is indicative of FLS1, the elapsed time for a signal traveling one way between fixed station 10 and fixed mobile unit 30 via satellite SI.
- the distance value Dl is the distance between fixed station 10 and satellite SI and can be expressed as follows:
- FIG 4 further illustrates the signals used in measuring the distance between fixed station 10 and secondary satellite S2.
- a forward link signal 44 Transmitted at antenna 10c, simultaneously and coordinated with the forward link signal 40 transmitted by fixed station antenna 10b, is a forward link signal 44.
- Forward link signal 44 is comprised of uplink portion 44a and downlink portions 44b and 44c.
- Forward link signal 44 is transmitted from antenna 10c (uplink portion 44a) via secondary satellite S2 to fixed mobile unit 30 (downlink portion 44b) collocated with fixed station 10 and remote fixed mobile unit 32 (downlink portion 44c).
- Fixed mobile unit 30 measures the percent offset of the sawtooth modulation of forward link signals 40 and 44. Fixed mobile unit 30 then transmits a return link signal 42, comprised of uplink and downlink portions 42a and 42b respedively, via primary satellite SI to fixed station 10.
- Return link signal 42 contains information indicative of a value DT corresponding to the time difference in reception between forward link signals 40b and 44b.
- the value FLS2 corresponding to the forward transmission delay between fixed station 10 and fixed mobile unit 30 through satellite S2 may be computed as follows:
- a distance value D2 corresponding to the distance from fixed station 10 to satellite S2 may be computed according to the following equation:
- c is the velodty of propagation of a radio signal in free space.
- Figure 4 further illustrates the signals used in determining the distance from primary satellite SI and secondary satellite S2 to other fixed observing sites. This process, as described herein with reference to the distance from satellites SI and S2 to fixed mobile unit 32, applies to finding the distance from satellites SI and S2 to all other fixed mobile units, such as fixed mobile unit 34 ( Figure 3).
- Fixed station 10 transmits upon antennas 10b and lQc simultaneous and coordinated forward link signals 40 and 44 respectively to fixed mobile unit 30, via primary satellite SI (uplink portion 40a and downlink portion 40c) and secondary satellite S2 (uplink portion 44a and downlink portion 44c)
- Fixed mobile unit 32 measures the percent offset of the periodic sawtooth modulation as received from signals 40 and 44.
- Fixed mobile unit 32 then transmits return link signal 46, comprised of uplink portion 46a and downlink portion 46b, via primary satellite SI to fixed station 10.
- Return link signal 46 is encoded with information indicative of the time difference DT, as derived from the percent offset in periodic modulation received.
- Fixed station 10 measures the round trip delay, RTD1A of the signal path combinations of 40 and 46 through comparison of return link dock offeet relative to the forward link dock. If RTDl A occurs at a different time than when Dl was calculated, an extrapolated value of Dl is used. This extrapolated Dl value is obtained by tracking the time-rate-of-change of Dl in addition to measuring current values of Dl in order to extrapolate future times. Dividing the time value RTD1A in half yields the propagation time value FLS1A of a radio signal traveling from fixed station 10 via primary satellite SI, to fixed mobile unit 32, i.e.
- time value FLS1 corresponds to the propagation time of signal 40a and 40b.
- the distance from secondary satellite S2 to fixed mobile unit 32 is similarly computed.
- the propagation time FLS2A of a signal traveling from fixed station 10 via secondary satellite S2 is equal to the propagation time value FLS1 plus the time difference value DT, i.e.
- This distance determination process may be expressed as follows:
- D2 may also be an extrapolated value, in similar fashion to the extrapolation used in computing the Dl value for the primary satellite.
- Trilateration is employed to obtain the cartesian x-y-z coordinates of primary satellite SI and secondary satellite S2 relative to the center of the earth.
- the collection of distances Dl and LS1A through LS1N are used to compute, using Kalman filtering in the trilateration process, the position of primary satellite SI in the cartesian x-y-z coordinate frame.
- the collection of distances D2 and LS2A through LS2N are used to compute, also using Kalman filtering in the trilateration method, the position of secondary satellite S2 in the cartesian x-y-z coordinate frame.
- a unit have a mobile communications terminal that is capable of measuring the percent offeet of the periodic modulation between the two simultaneously transmitted and coordinated signals from fixed station 10.
- This time difference measurement, DT is achieved by essentially comparing replicas of the waveform to the two signals received at the mobile unit terminal. This is referred to as matched filtering known in the art. A peak detection in energy identifies when a match is made. The amoimt of phase offeet difference in the replica waveform that is required to deted energy from both signals determines the time difference value DT.
- UCT Universal Coordinated Time
- FIG. 5 is an exemplary illustration of timing signals as received at a mobile unit terminal.
- the forward signals are identical with resped to signal carrier waveform except for a unique identifier such as the center frequency when originally transmitted from the antennas of the fixed station. Since these signals are synchronized, their waveforms initially overlap. When the signals, for example signals 20 and 22 of Figure 2, reach the mobile unit, be it in motion or fixed, their waveforms no longer overlap because they have traversed paths of different lengths.
- the signal carrier waveform of the signals 20 and 22 as shown in Figure 5 are as received at a mobile unit.
- the signal carriers are swept linearly up and down in frequency from a nominal base or center frequency in a chirping manner.
- the base frequency of signals 20 and 22 may be the same if polarization is used to identify each signal. Alternatively the base frequency for signals 20 and 22 would be different.
- the base frequency from which the carrier is chirped is about 14 GHz with frequency chirping over a typical 2 MHz bandwidth.
- These signals emulate video signals for which conventional satellite transponders are configured to operate. Emulation of the video signal reduces interference to terminals which are not tuned to receive such signals.
- Each linear up /down frequency sweep or frequency chirp period in the preferred embodiment is approximately 30 milliseconds.
- a triangle chirp waveform on the forward link signal is particularly suited to permit measuring of phase offsets at the objed of the forward link signals when relayed through two or more satellites.
- the difference in time of arrival of timing signals 20 and 22 can be no greater than 8 milliseconds.
- a mobile unit making the DT measurement can thus unambiguously measure the difference in arrival times by measuring the offeet of one of the waveforms with respect to the other.
- Figure 7 illustrates one embodiment in communications between fixed station 10 via satellites SI and S2 to two different groups of users respectively represented by mobile units 32 and 36.
- Signals transmitted between fixed station 10 and mobile units 32 and 36 via satellites SI and S2 containing message data modulated upon a carrier signal are illustrated as solid lines.
- the dashed lines illustrate communication forward link signals for one group of users which are borrowed as ranging signals for the other group of users, and thus serve as replicas of the forward link periodic modulation.
- the ranging signals are used only for the chirping periodic pattern with the digital information on these signals, intended for another user group, is not demodulated.
- Satellites SI and S2 respectively carry a typical transponder payload with each satellite having multiple transponders.
- satellite SI indudes transponders Sla and Sib.
- satellite S2 indudes transponders S2a and S2b.
- Mobile unit 32 provides a return link communication signal comprised of uplink portion 52a and downlink portion 52b via transponder Sib to antenna 10b.
- a coordinated ranging signal which happens to be the forward link communication signal for mobile unit 36, is transmitted from antenna 10c to mobile unit 32 via transponder S2a of satellite S2.
- the uplink and downlink portions of this ranging signal are respectively identified by the reference numerals 56a and 56b'. This ranging signal along with the techniques previously discussed are used in determining the position of mobile unit 32.
- Fixed station 10 transmits a forward link communication signal comprised of uplink portion 56a and downlink portion 56b from antenna 10c via transponder S2a of satellite S2 to mobile unit 36.
- a return link communication signal is comprised of uplink portion 58a and downlink portion 58b which is transmitted from mobile unit 36 via transponder S2b to fixed station 10 where received at antenna 10c.
- a coordinated ranging signal which also happens to be the forward link communication signal for mobile unit 32, is transmitted from antenna 10b to mobile unit 36 via transponder Sla of satellite SI.
- the uplink and downlink portions of this ranging signal are respectively identified by the reference numerals 50a and 50b'. This ranging signal along with title previously discussed techniques are used in determining the position of mobile unit 36.
- Figure 8 illustrates an alternate embodiment of the communication system utilizing only three transponders, two transponders on one satellite and one transponder on another satellite.
- fixed station 10 transmits a forward link communication signal comprised of uplink portions 70a and 70b via transponder Sla of satellite SI to mobile unit 32 of the first user group.
- a return link communication signal comprised of uplink portion 72a and downlink portion 72b is transmitted from mobile unit 32 to antenna 10b of fixed station 10 via transponder Slb of satellite SI.
- the ranging signal which is the forward link communication signal between fixed station 10 and truck 36 comprised of uplink and downlink portions 76a and 76b, is transmitted upon antenna 10c.
- This ranging signal comprised of uplink portion 76a and downlink portion 76b, is relayed to mobile unit 32 via transponder S2a of satellite S2. As discussed above, the ranging signal and the previously discussed techniques are utilized in determining the position of the mobile unit 32.
- Fixed station 10 also communicates with the second user group as represented by mobile unit 36.
- a forward link communication signal comprised of uplink portion 76a and downlink portion 76b is transmitted from antenna 10c via transponder S2a of satellite S2 to mobile unit 36.
- a return link communication signal comprised of uplink portion 78a and downlink portion 78b is transmitted from mobile unit 36 via transponder Slb of satellite SI to antenna 10b of fixed station 10.
- the ranging signal which is the forward link communication signal for mobile unit 32, comprised of uplink and downlink portions 70a and 70b, is transmitted from fixed station 10.
- This ranging signal is comprised of uplink portion 70a and downlink portion 70b' and is transmitted from antenna 10b via transponder Sla of satellite SI to mobile unit 36.
- This ranging signal and the previously discussed techniques are utilized in determining the position of mobile unit 36.
- each satellite would serve as a primary satellite for communications for a respective user group.
- Each satellite would also serve as a secondary satellite for ranging purposes for the other user group.
- a single transponder would handle both forward and return link communications for one user group in addition to the ranging signal for the other user group.
- the return signal from each user would be returned through a corresponding primary satellite transponder or through a designated same transponder of one of the primary or secondary satellites.
- signals would coexist in typically the same bandwidth and are identifiable from one another using known techniques.
Abstract
Description
Claims
Priority Applications (9)
Application Number | Priority Date | Filing Date | Title |
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EP91901367A EP0504281B1 (en) | 1989-12-05 | 1990-11-30 | Dual satellite navigation method and system |
BR909007896A BR9007896A (en) | 1989-12-05 | 1990-11-30 | PROCESS AND SYSTEM FOR DETERMINING THE POSITION OF AN OBJECT IN A SYSTEM OF REFERENCE COORDINATES, AND USING A PLATALITY OF SATELLITE IN EARTH ORBIT AND A FIXED STATION |
DK91901367T DK0504281T3 (en) | 1989-12-05 | 1990-11-30 | Dual satellite navigation method and system |
DE69032664T DE69032664T2 (en) | 1989-12-05 | 1990-11-30 | NAVIGATION PROCESS AND SYSTEM WITH TWO SATELLITES |
CA002073053A CA2073053C (en) | 1989-12-05 | 1990-11-30 | Dual satellite navigation method and system |
SU905011890A RU2084916C1 (en) | 1989-12-05 | 1990-11-30 | Method and system for detection of object position |
NO922212A NO300248B1 (en) | 1989-12-05 | 1992-06-04 | Method and system for dual satellite navigation |
FI922629A FI107084B (en) | 1989-12-05 | 1992-06-05 | Double satellite navigation method and system |
HK98116096A HK1014811A1 (en) | 1989-12-05 | 1998-12-28 | Dual satellite navigation method and system |
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US446,979 | 1989-12-05 | ||
US07/446,979 US5017926A (en) | 1989-12-05 | 1989-12-05 | Dual satellite navigation system |
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EP (1) | EP0504281B1 (en) |
AT (1) | ATE171278T1 (en) |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2320385A (en) * | 1996-12-14 | 1998-06-17 | Ico Services Ltd | Locating user of satellite communications |
GB2321812A (en) * | 1997-02-01 | 1998-08-05 | Ico Services Ltd | User terminal position determining system |
EP2703841A1 (en) * | 2012-08-31 | 2014-03-05 | O2Micro, Inc. | Method and apparatus for synchronizing navigation data |
CN103675853A (en) * | 2012-08-31 | 2014-03-26 | 迈实电子(上海)有限公司 | Navigation message synchronization method, receiver and device |
Families Citing this family (101)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5126748A (en) * | 1989-12-05 | 1992-06-30 | Qualcomm Incorporated | Dual satellite navigation system and method |
US5073900A (en) * | 1990-03-19 | 1991-12-17 | Mallinckrodt Albert J | Integrated cellular communications system |
US5446756A (en) * | 1990-03-19 | 1995-08-29 | Celsat America, Inc. | Integrated cellular communications system |
JP2979582B2 (en) * | 1990-05-23 | 1999-11-15 | ソニー株式会社 | Transmission system |
US5160935A (en) * | 1990-11-28 | 1992-11-03 | Mitsubishi Denki Kabushiki Kaisha | Positioning method utilizing artificial satellites in geosynchronous altitude orbits |
US5202829A (en) * | 1991-06-10 | 1993-04-13 | Trimble Navigation Limited | Exploration system and method for high-accuracy and high-confidence level relative position and velocity determinations |
US5365447A (en) * | 1991-09-20 | 1994-11-15 | Dennis Arthur R | GPS and satelite navigation system |
DE4136136C1 (en) * | 1991-11-02 | 1993-03-04 | Westdeutscher Rundfunk, Anstalt Des Oeffentlichen Rechts, 5000 Koeln, De | |
US10361802B1 (en) | 1999-02-01 | 2019-07-23 | Blanding Hovenweep, Llc | Adaptive pattern recognition based control system and method |
US8352400B2 (en) | 1991-12-23 | 2013-01-08 | Hoffberg Steven M | Adaptive pattern recognition based controller apparatus and method and human-factored interface therefore |
US5278863A (en) * | 1992-04-10 | 1994-01-11 | Cd Radio Incorporated | Radio frequency broadcasting systems and methods using two low-cost geosynchronous satellites |
US5347285A (en) * | 1992-06-15 | 1994-09-13 | A.I.R., Inc. | Method and apparatus for tracking the position and velocity of airborne instrumentation |
US5430759A (en) * | 1992-08-20 | 1995-07-04 | Nexus 1994 Limited | Low-power frequency-hopped spread spectrum reverse paging system |
US5335246A (en) * | 1992-08-20 | 1994-08-02 | Nexus Telecommunication Systems, Ltd. | Pager with reverse paging facility |
US5422813A (en) * | 1992-12-17 | 1995-06-06 | Stanford Telecommunications, Inc. | No-outage GPS/commercial RF positioning system |
EP0664008B1 (en) * | 1993-08-06 | 1998-12-23 | A.I.R., Inc. | Method and apparatus for tracking the position and velocity of airborne instrumentation |
US5530452A (en) * | 1993-10-21 | 1996-06-25 | Nexus Telecommunication Systems Ltd. | Method of synchronizing spread spectrum radio transmitters |
US5572216A (en) * | 1993-11-19 | 1996-11-05 | Stanford Telecommunications, Inc. | System for increasing the utility of satellite communication systems |
US5485163A (en) * | 1994-03-30 | 1996-01-16 | Motorola, Inc. | Personal locator system |
WO1995027964A1 (en) * | 1994-04-12 | 1995-10-19 | Qualcomm Incorporated | Method and apparatus for freight transportation using a satellite navigation system |
US5506781A (en) * | 1994-06-03 | 1996-04-09 | Itt Corporation | RF link control of satellite clocks |
US5592471A (en) * | 1995-04-21 | 1997-01-07 | Cd Radio Inc. | Mobile radio receivers using time diversity to avoid service outages in multichannel broadcast transmission systems |
WO1996039781A1 (en) * | 1995-06-06 | 1996-12-12 | Flash Comm, Inc. | Determining propagating and clear frequency in wireless data communications network |
US5734963A (en) * | 1995-06-06 | 1998-03-31 | Flash Comm, Inc. | Remote initiated messaging apparatus and method in a two way wireless data communications network |
US5765112A (en) * | 1995-06-06 | 1998-06-09 | Flash Comm. Inc. | Low cost wide area network for data communication using outbound message specifying inbound message time and frequency |
US6885652B1 (en) | 1995-06-30 | 2005-04-26 | Interdigital Technology Corporation | Code division multiple access (CDMA) communication system |
ZA965340B (en) | 1995-06-30 | 1997-01-27 | Interdigital Tech Corp | Code division multiple access (cdma) communication system |
US7929498B2 (en) | 1995-06-30 | 2011-04-19 | Interdigital Technology Corporation | Adaptive forward power control and adaptive reverse power control for spread-spectrum communications |
US7123600B2 (en) | 1995-06-30 | 2006-10-17 | Interdigital Technology Corporation | Initial power control for spread-spectrum communications |
US7020111B2 (en) | 1996-06-27 | 2006-03-28 | Interdigital Technology Corporation | System for using rapid acquisition spreading codes for spread-spectrum communications |
US6522890B2 (en) | 1995-12-22 | 2003-02-18 | Cambridge Positioning Systems, Ltd. | Location and tracking system |
AUPN733395A0 (en) * | 1995-12-22 | 1996-01-25 | University Of Technology, Sydney | Location and tracking system |
US5986603A (en) * | 1996-02-14 | 1999-11-16 | Trimble Navigation Limited | Geometric utilization of exact solutions of the pseudorange equations |
US6223019B1 (en) | 1996-03-14 | 2001-04-24 | Sirius Satellite Radio Inc. | Efficient high latitude service area satellite mobile broadcasting systems |
US5774802A (en) * | 1996-04-10 | 1998-06-30 | Motorola Inc. | Apparatus and method for billing in a wireless communication system |
US6020847A (en) * | 1996-04-25 | 2000-02-01 | Twr Inc. | Geolocation method and apparatus for satellite based telecommunications system |
US5878034A (en) * | 1996-05-29 | 1999-03-02 | Lockheed Martin Corporation | Spacecraft TDMA communications system with synchronization by spread spectrum overlay channel |
US5917433A (en) * | 1996-06-26 | 1999-06-29 | Orbital Sciences Corporation | Asset monitoring system and associated method |
US6084870A (en) * | 1996-07-22 | 2000-07-04 | Qualcomm Incorporated | Method and apparatus for the remote monitoring and configuration of electronic control systems |
US7714778B2 (en) | 1997-08-20 | 2010-05-11 | Tracbeam Llc | Wireless location gateway and applications therefor |
US6236365B1 (en) | 1996-09-09 | 2001-05-22 | Tracbeam, Llc | Location of a mobile station using a plurality of commercial wireless infrastructures |
US7274332B1 (en) | 1996-09-09 | 2007-09-25 | Tracbeam Llc | Multiple evaluators for evaluation of a purality of conditions |
US9134398B2 (en) | 1996-09-09 | 2015-09-15 | Tracbeam Llc | Wireless location using network centric location estimators |
US6249252B1 (en) | 1996-09-09 | 2001-06-19 | Tracbeam Llc | Wireless location using multiple location estimators |
US7903029B2 (en) | 1996-09-09 | 2011-03-08 | Tracbeam Llc | Wireless location routing applications and architecture therefor |
CA2265875C (en) | 1996-09-09 | 2007-01-16 | Dennis Jay Dupray | Location of a mobile station |
US5781151A (en) * | 1996-09-19 | 1998-07-14 | Parker-Hannifin Corporation | Interferometric trajectory reconstruction technique for flight inspection of radio navigation aids |
US6151308A (en) * | 1996-12-30 | 2000-11-21 | Motorola, Inc. | Elevated communication hub and method of operation therefor |
US5914686A (en) * | 1997-01-11 | 1999-06-22 | Trimble Navigation Limited | Utilization of exact solutions of the pseudorange equations |
US6023616A (en) * | 1998-03-10 | 2000-02-08 | Cd Radio Inc. | Satellite broadcast receiver system |
US5974356A (en) * | 1997-03-14 | 1999-10-26 | Qualcomm Incorporated | System and method for determining vehicle travel routes and mileage |
US5955986A (en) * | 1997-11-20 | 1999-09-21 | Eagle Eye Technologies, Inc. | Low-power satellite-based geopositioning system |
US6108591A (en) | 1998-01-22 | 2000-08-22 | Qualcomm Incorporated | Method and apparatus for validating vehicle operators |
US7268700B1 (en) | 1998-01-27 | 2007-09-11 | Hoffberg Steven M | Mobile communication device |
US6208937B1 (en) * | 1998-07-29 | 2001-03-27 | Litton Systems Inc. | Method and apparatus for generating navigation data |
US6124810A (en) | 1998-09-15 | 2000-09-26 | Qualcomm Incorporated | Method and apparatus for automatic event detection in a wireless communication system |
US8135413B2 (en) | 1998-11-24 | 2012-03-13 | Tracbeam Llc | Platform and applications for wireless location and other complex services |
US7904187B2 (en) | 1999-02-01 | 2011-03-08 | Hoffberg Steven M | Internet appliance system and method |
GB9912724D0 (en) | 1999-06-01 | 1999-08-04 | Cambridge Positioning Sys Ltd | Radio positioning system |
US6560536B1 (en) | 1999-07-12 | 2003-05-06 | Eagle-Eye, Inc. | System and method for rapid telepositioning |
US8255149B2 (en) | 1999-07-12 | 2012-08-28 | Skybitz, Inc. | System and method for dual-mode location determination |
US6480788B2 (en) | 1999-07-12 | 2002-11-12 | Eagle-Eye, Inc. | System and method for fast acquisition reporting using communication satellite range measurement |
US20040143392A1 (en) * | 1999-07-12 | 2004-07-22 | Skybitz, Inc. | System and method for fast acquisition reporting using communication satellite range measurement |
GB2352347A (en) * | 1999-07-22 | 2001-01-24 | Ico Services Ltd | Location of a user terminal in a satellite and earth station network |
JP3595738B2 (en) * | 1999-08-30 | 2004-12-02 | 松下電器産業株式会社 | Distance detecting method, position detecting method and device therefor |
EP1286735A1 (en) | 1999-09-24 | 2003-03-05 | Dennis Jay Dupray | Geographically constrained network services |
US10641861B2 (en) | 2000-06-02 | 2020-05-05 | Dennis J. Dupray | Services and applications for a communications network |
US10684350B2 (en) | 2000-06-02 | 2020-06-16 | Tracbeam Llc | Services and applications for a communications network |
US9875492B2 (en) | 2001-05-22 | 2018-01-23 | Dennis J. Dupray | Real estate transaction system |
CA2418855A1 (en) | 2000-08-09 | 2002-02-14 | Skybitz, Inc. | System and method for fast code phase and carrier frequency acquisition in gps receiver |
WO2002025829A1 (en) * | 2000-09-18 | 2002-03-28 | Skybitz, Inc. | System and method for fast code phase and carrier frequency acquisition in gps receiver |
US7995989B2 (en) * | 2000-12-29 | 2011-08-09 | Globalstar, Inc. | Method and apparatus providing suppression of system access by use of confidence polygons, volumes and surfaces in a mobile satellite system |
US8082096B2 (en) | 2001-05-22 | 2011-12-20 | Tracbeam Llc | Wireless location routing applications and architecture therefor |
US7212984B2 (en) * | 2001-10-29 | 2007-05-01 | Qualcomm Incorporated | Method and apparatus for providing virtual capacity to a provider of services |
US7765297B2 (en) * | 2001-11-13 | 2010-07-27 | Qualcomm Incorporated | System for providing online service reports |
US7738533B2 (en) | 2002-01-07 | 2010-06-15 | Qualcomm Incorporated | Multiplexed CDMA and GPS searching |
US6873905B2 (en) * | 2002-03-19 | 2005-03-29 | Opnext Japan, Inc. | Communications type navigation device |
US9818136B1 (en) | 2003-02-05 | 2017-11-14 | Steven M. Hoffberg | System and method for determining contingent relevance |
US20050095982A1 (en) * | 2003-11-05 | 2005-05-05 | Blanchard Scott D. | MSS user equipment and methods for synchronizing MSS user equipment |
JP4848146B2 (en) * | 2005-07-05 | 2011-12-28 | 船井電機株式会社 | Apparatus for transmitting positioning signal, positioning system including the apparatus, and system for transmitting positioning signal |
ATE466417T1 (en) * | 2005-08-09 | 2010-05-15 | Atc Tech Llc | SATELLITE COMMUNICATION SYSTEMS AND METHODS USING SUBSTANTIALLY ADJACENT RADIO CONNECTION ANTENNAS |
US8981996B2 (en) | 2005-09-27 | 2015-03-17 | Qualcomm Incorporated | Position location using transmitters with timing offset and phase adjustment |
US9354297B2 (en) * | 2005-09-27 | 2016-05-31 | Qualcomm Incorporated | Position location using phase-adjusted transmitters |
US8300798B1 (en) | 2006-04-03 | 2012-10-30 | Wai Wu | Intelligent communication routing system and method |
US7468696B2 (en) * | 2006-12-14 | 2008-12-23 | The Boeing Company | Method and device for trilateration using LOS link prediction and pre-measurement LOS path filtering |
US7760077B2 (en) * | 2007-06-05 | 2010-07-20 | Qualcomm Incorporated | Establishing and securing a unique wireless RF link between a tractor and a trailer using a wired connection |
EP2168323B1 (en) * | 2007-06-18 | 2012-10-03 | Telefonaktiebolaget LM Ericsson (publ) | Cooperative traffic scheduling |
US9305405B2 (en) * | 2007-06-26 | 2016-04-05 | Omnitracs, Llc | Reefer fuel tax reporting for the transport industry |
US8370063B2 (en) * | 2008-10-29 | 2013-02-05 | Telenav, Inc. | Navigation system having filtering mechanism and method of operation thereof |
US9538493B2 (en) | 2010-08-23 | 2017-01-03 | Finetrak, Llc | Locating a mobile station and applications therefor |
CN102830410B (en) * | 2011-06-17 | 2014-09-03 | 中国科学院国家天文台 | Positioning method in combination with Doppler velocity measurement in satellite navigation |
CN103675839A (en) * | 2012-08-31 | 2014-03-26 | 迈实电子(上海)有限公司 | Navigation message synchronization method, receiver and device |
CN103675838A (en) * | 2012-08-31 | 2014-03-26 | 迈实电子(上海)有限公司 | Navigation message synchronization method, receiver and device |
CN103675837A (en) * | 2012-08-31 | 2014-03-26 | 迈实电子(上海)有限公司 | Navigation message synchronization method, receiver and device |
EP2735883A1 (en) * | 2012-11-27 | 2014-05-28 | Eutelsat S.A. | Method of geo localization of a terminal sending a single signal to a satellite |
RU2579934C1 (en) * | 2015-03-03 | 2016-04-10 | Андрей Алексеевич Панкин | Method of detecting unauthorised actions on satellite communication network |
US10591609B1 (en) | 2017-01-11 | 2020-03-17 | Telephonics Corp. | System and method for providing accurate position location information to military forces in a disadvantaged signal environment |
RU2678371C2 (en) * | 2017-07-14 | 2019-01-28 | Валерий Дмитриевич Федорищев | Mobile objects coordinates and axes position angles determining method by means of installed on objects and observation points atomic clocks |
CN112526574A (en) * | 2020-11-30 | 2021-03-19 | 中国电子科技集团公司第五十四研究所 | Satellite positioning method and device |
CN113466790B (en) * | 2021-06-22 | 2024-03-01 | 西安理工大学 | Roland positioning calculation algorithm |
CN116256788B (en) * | 2023-05-11 | 2023-07-11 | 中国人民解放军战略支援部队航天工程大学 | Space geometric iteration satellite positioning method based on Apollonius circle |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3384891A (en) * | 1965-02-11 | 1968-05-21 | Gen Electric | Method and system for long distance navigation and communication |
US3544995A (en) * | 1967-07-21 | 1970-12-01 | Siemens Ag | Navigation method with the aid of satellites |
US4359733A (en) * | 1980-09-23 | 1982-11-16 | Neill Gerard K O | Satellite-based vehicle position determining system |
Family Cites Families (34)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2746034A (en) * | 1951-06-01 | 1956-05-15 | Olive S Petty | Positioning determining system |
US2972742A (en) * | 1956-09-12 | 1961-02-21 | Ibm | Automatic position-reporting system |
US3047861A (en) * | 1959-06-25 | 1962-07-31 | Lockheed Aircraft Corp | Aircraft traffic control and surveillance system |
US3209357A (en) * | 1963-01-10 | 1965-09-28 | Wyatt Theodore | Hyperbolic position determination |
GB1084110A (en) * | 1965-05-05 | |||
US3497807A (en) * | 1966-08-31 | 1970-02-24 | Us Navy | Multipurpose satellite system |
US3742495A (en) * | 1966-11-07 | 1973-06-26 | Goodyear Aerospace Corp | Drone guidance system and method |
US3534367A (en) * | 1968-01-30 | 1970-10-13 | Nasa | Traffic control system and method |
US3495260A (en) * | 1968-01-30 | 1970-02-10 | Nasa | Position location system and method |
US3668403A (en) * | 1969-05-05 | 1972-06-06 | Goodyear Aerospace Corp | Method and apparatus for vehicle traffic control |
US3988734A (en) * | 1969-06-16 | 1976-10-26 | Elwood Albert A | Method of and system for locating a position |
US3624650A (en) * | 1969-09-09 | 1971-11-30 | Nasa | Method and apparatus for mapping planets |
US3611379A (en) * | 1969-09-29 | 1971-10-05 | Trw Inc | Tracking system |
US3742498A (en) * | 1970-05-06 | 1973-06-26 | Itt | Synchronization and position location system |
US3766552A (en) * | 1970-12-14 | 1973-10-16 | M Hajduk | Unified area surveillance, communication and mobile station guidance system |
DE2128524B2 (en) * | 1971-06-08 | 1976-10-21 | Siemens AG, 1000 Berlin und 8000 München | AIRPLANE NAVIGATION ANTENNA SYSTEM |
US3750166A (en) * | 1971-06-11 | 1973-07-31 | J Dearth | Pilot data system |
US3810179A (en) * | 1971-11-04 | 1974-05-07 | Del Norte Technology | Radar trilateralization position locators |
US3918056A (en) * | 1971-11-04 | 1975-11-04 | Del Norte Technology | Radar trilateralization position locators |
US3886553A (en) * | 1973-03-15 | 1975-05-27 | John K Bates | Coordinate locating method and system |
US4042923A (en) * | 1973-11-30 | 1977-08-16 | Del Norte Technology, Inc. | Radar trilateralization position locators |
US3889122A (en) * | 1974-04-26 | 1975-06-10 | Nasa | Method of determining bond quality of power transistors attached to substrates |
US4387373A (en) * | 1977-04-21 | 1983-06-07 | Westinghouse Electric Corp. | Synthetic monopulse radar |
US4179693A (en) * | 1977-05-23 | 1979-12-18 | Rockwell Internation Corporation | Autonomous, check-pointing, navigational system for an airborne vehicle |
US4161730A (en) * | 1977-10-17 | 1979-07-17 | General Electric Company | Radio determination using satellites transmitting timing signals with correction by active range measurement |
US4170776A (en) * | 1977-12-21 | 1979-10-09 | Nasa | System for near real-time crustal deformation monitoring |
US4224669A (en) * | 1977-12-22 | 1980-09-23 | The Boeing Company | Minimum safe altitude monitoring, indication and warning system |
GB2032723B (en) * | 1978-10-26 | 1988-09-07 | Marconi Co Ltd | Improvements in or relating to radar systems |
US4292634A (en) * | 1978-12-15 | 1981-09-29 | Nasa | Real-time multiple-look synthetic aperture radar processor for spacecraft applications |
US4472720A (en) * | 1980-03-24 | 1984-09-18 | Reesor Thomas W | Area navigational system using geosynchronous satellites |
US4386355A (en) * | 1980-03-31 | 1983-05-31 | The Boeing Company | System for determining the location of an airborne vehicle to the earth using a satellite-base signal source |
US4445120A (en) * | 1981-04-07 | 1984-04-24 | The United States Of America As Represented By The Secretary Of The Navy | Radiosonde |
US4839656A (en) * | 1984-08-16 | 1989-06-13 | Geostar Corporation | Position determination and message transfer system employing satellites and stored terrain map |
US4744083A (en) * | 1984-09-14 | 1988-05-10 | Geostar Corporation | Satellite-based position determining and message transfer system with monitoring of link quality |
-
1989
- 1989-12-05 US US07/446,979 patent/US5017926A/en not_active Expired - Lifetime
-
1990
- 1990-11-30 CA CA002073053A patent/CA2073053C/en not_active Expired - Lifetime
- 1990-11-30 ES ES91901367T patent/ES2122970T3/en not_active Expired - Lifetime
- 1990-11-30 DK DK91901367T patent/DK0504281T3/en active
- 1990-11-30 WO PCT/US1990/007005 patent/WO1991008622A1/en active IP Right Grant
- 1990-11-30 AU AU70371/91A patent/AU647337B2/en not_active Expired
- 1990-11-30 SG SG1996006193A patent/SG78252A1/en unknown
- 1990-11-30 DE DE69032664T patent/DE69032664T2/en not_active Expired - Lifetime
- 1990-11-30 AT AT91901367T patent/ATE171278T1/en not_active IP Right Cessation
- 1990-11-30 RU SU905011890A patent/RU2084916C1/en active
- 1990-11-30 EP EP91901367A patent/EP0504281B1/en not_active Expired - Lifetime
- 1990-11-30 BR BR909007896A patent/BR9007896A/en not_active IP Right Cessation
- 1990-12-04 MX MX23584A patent/MX164485B/en unknown
-
1992
- 1992-06-04 NO NO922212A patent/NO300248B1/en not_active IP Right Cessation
- 1992-06-05 FI FI922629A patent/FI107084B/en active
-
1998
- 1998-12-28 HK HK98116096A patent/HK1014811A1/en not_active IP Right Cessation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3384891A (en) * | 1965-02-11 | 1968-05-21 | Gen Electric | Method and system for long distance navigation and communication |
US3544995A (en) * | 1967-07-21 | 1970-12-01 | Siemens Ag | Navigation method with the aid of satellites |
US4359733A (en) * | 1980-09-23 | 1982-11-16 | Neill Gerard K O | Satellite-based vehicle position determining system |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2320385A (en) * | 1996-12-14 | 1998-06-17 | Ico Services Ltd | Locating user of satellite communications |
GB2320385B (en) * | 1996-12-14 | 2001-06-06 | Ico Services Ltd | Satellite communication system and method |
GB2357921A (en) * | 1996-12-14 | 2001-07-04 | Ico Services Ltd | Locating user of satellite communications |
GB2357920A (en) * | 1996-12-14 | 2001-07-04 | Ico Services Ltd | Locating user of satellite communications |
GB2357921B (en) * | 1996-12-14 | 2001-08-22 | Ico Services Ltd | Satellite communication system and method |
GB2357920B (en) * | 1996-12-14 | 2001-08-22 | Ico Services Ltd | Satellite communications system and method |
US6816705B1 (en) | 1996-12-14 | 2004-11-09 | Ico Services Ltd. | Satellite communication system and method |
GB2321812A (en) * | 1997-02-01 | 1998-08-05 | Ico Services Ltd | User terminal position determining system |
US6031489A (en) * | 1997-02-01 | 2000-02-29 | Ico Services Ltd. | User terminal positioning system and method employing external signals |
GB2321812B (en) * | 1997-02-01 | 2001-02-21 | Ico Services Ltd | User terminal positioning system and method employing external signals |
EP2703841A1 (en) * | 2012-08-31 | 2014-03-05 | O2Micro, Inc. | Method and apparatus for synchronizing navigation data |
CN103675853A (en) * | 2012-08-31 | 2014-03-26 | 迈实电子(上海)有限公司 | Navigation message synchronization method, receiver and device |
Also Published As
Publication number | Publication date |
---|---|
FI922629A (en) | 1992-06-05 |
BR9007896A (en) | 1992-08-25 |
ES2122970T3 (en) | 1999-01-01 |
NO922212L (en) | 1992-06-04 |
CA2073053A1 (en) | 1991-06-06 |
DK0504281T3 (en) | 1999-06-14 |
CA2073053C (en) | 2000-01-18 |
AU7037191A (en) | 1991-06-26 |
FI922629A0 (en) | 1992-06-05 |
HK1014811A1 (en) | 1999-09-30 |
EP0504281A4 (en) | 1993-07-07 |
EP0504281A1 (en) | 1992-09-23 |
US5017926A (en) | 1991-05-21 |
MX164485B (en) | 1992-08-19 |
AU647337B2 (en) | 1994-03-17 |
DE69032664T2 (en) | 1999-05-12 |
FI107084B (en) | 2001-05-31 |
ATE171278T1 (en) | 1998-10-15 |
RU2084916C1 (en) | 1997-07-20 |
SG78252A1 (en) | 2001-02-20 |
NO922212D0 (en) | 1992-06-04 |
EP0504281B1 (en) | 1998-09-16 |
DE69032664D1 (en) | 1998-10-22 |
NO300248B1 (en) | 1997-04-28 |
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