CA2278445A1 - Receiver for use in a transmission system for spectral-coded data as well as a method - Google Patents
Receiver for use in a transmission system for spectral-coded data as well as a method Download PDFInfo
- Publication number
- CA2278445A1 CA2278445A1 CA002278445A CA2278445A CA2278445A1 CA 2278445 A1 CA2278445 A1 CA 2278445A1 CA 002278445 A CA002278445 A CA 002278445A CA 2278445 A CA2278445 A CA 2278445A CA 2278445 A1 CA2278445 A1 CA 2278445A1
- Authority
- CA
- Canada
- Prior art keywords
- optical
- frequency
- receiver
- fact
- electrical signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/67—Optical arrangements in the receiver
- H04B10/671—Optical arrangements in the receiver for controlling the input optical signal
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
- Optical Filters (AREA)
Abstract
The invention relates to a method for the reception of spectral-coded data and a receiver, whereby an optical signal is decoded, converted into an electrical signal and amplified, and whereby the optical signal is modulated by the modulation of the synchronization of the optical filter in a first frequency, the modulated signal is converted in a light-sensitive detector into an electrical signal of a second frequency, and this electrical signal is transformed in a detector back into the base band.
Description
RECEIVER FOR USE IN A TRANSMISSION SYSTEM FOR SPECTRAL
CODED DATA AS WELL AS A METHOD
This invention relates to a receiver for use in a transmission system for spectral-coded data and a method as described in the independent claims.
The prior art, such as Patent Application DE 197 23 103.9, for example, discloses transmission methods that employ spectral coding. Such a transmission network consists of optical transmission lines and optical splatters, as well as optical amplifiers if necessary, and is used for the transmission of coded, multiplexed optical signals. Each transmitter contains a coder in which the signals to be transmitted are coded before they are dispatched into the optical transmission network. The coding is done optically, e.g. by frequency coding using an optical filter. Each receiver that wants to receive the data from a special transmitter must contain a decoder that is synchronized to the encoder of this specific transmitter. In the simplest case, the frequency ranges that are permeable for optical signals and the frequency ranges that are blocked for optical signals are the same in the coder and in the decoder. This method is known by the term CDMA (Code Division Multiple Access) . The senders used in this system can be light-emitting diodes, for example, the broad-band emission spectrum of which runs through an optical filter.
The optical filter can be a Fabry-Perot filter, for example, that converts the broad-band spectrum in a frequency polarization comb assembly.
On the receiving side, Patent Application DE 19723103.9, for example, discloses a differential receiver. Such a receiver contains a decoder that is synchronized to the coder of the transmitter, the optical signals of which it wants to or is authorized to receive. In particular, the simultaneous activity of a plurality of transmitters in the optical transmission leads to side-to-side crosstalk in the receiver of the optical signals from the transmitters. The signals to be detected, therefore, also contain portions of optical signals from other transmitters which are experienced as interference. The prior art discloses ways to suppress this interference by compensation in the differential receiver. Such a receiver with compensation of the two signal branches is disclosed, for example, in Patent Application DE 19748756.4. In the optical differential receiver for frequency-coded optical CDMA
systems disclosed in this patent, it is necessary, within the electrical modulation bandwidth, e.g., 108 MHz for a n~155 MBit/s system, to guarantee the synchronization of the two receiver arms with regard to the amplitude and phase shifts of the signals of less than 0.1 dB and < 10 ps for all frequencies. It is thereby possible to achieve a bit error rate of < 10-9, for example. The requirements for such an optical differential amplifier, however, increase with the number of simultaneous transmitters in the network, so that it becomes increasingly more difficult to connect much more than 8 transmitters to the network. For large numbers of transmitters, therefore, the concept of the differential receiver must be discarded. Nevertheless, the receiver claimed by the invention can be used to achieve the necessary suppression of the side-to-side crosstalk of the channels that are not to be received.
The receiver claimed by the invention with the characterizing features disclosed in Claim 1 has the advantage over similar devices of the prior art that a high number of transmitters can be operated in a transmission system. The sensitivity to crosstalk is largely eliminated by modulation of the optical signal.
Advantageous refinements and improvements of the receiver disclosed in the independent claim are possible with the features disclosed in the subclaims.
It is advantageous if, in the receiver, a high suppression of the side-to-side crosstalk of the other channels is guaranteed by a modulation of the filter characteristic of the optical filter. The modulation of the optical filter is advantageously performed at a high frequency, and the modulated signal is evaluated with a microwave detector.
In one advantageous embodiment, the optical decoder is a Mach-Zehnder filter. Another embodiment uses a Fabry-Perot filter as the optical decoder. The optical filter is advantageously connected directly with a microwave generator. The modulation frequency is thereby always greater than the frequency of the bit rate of the data transmission.
CODED DATA AS WELL AS A METHOD
This invention relates to a receiver for use in a transmission system for spectral-coded data and a method as described in the independent claims.
The prior art, such as Patent Application DE 197 23 103.9, for example, discloses transmission methods that employ spectral coding. Such a transmission network consists of optical transmission lines and optical splatters, as well as optical amplifiers if necessary, and is used for the transmission of coded, multiplexed optical signals. Each transmitter contains a coder in which the signals to be transmitted are coded before they are dispatched into the optical transmission network. The coding is done optically, e.g. by frequency coding using an optical filter. Each receiver that wants to receive the data from a special transmitter must contain a decoder that is synchronized to the encoder of this specific transmitter. In the simplest case, the frequency ranges that are permeable for optical signals and the frequency ranges that are blocked for optical signals are the same in the coder and in the decoder. This method is known by the term CDMA (Code Division Multiple Access) . The senders used in this system can be light-emitting diodes, for example, the broad-band emission spectrum of which runs through an optical filter.
The optical filter can be a Fabry-Perot filter, for example, that converts the broad-band spectrum in a frequency polarization comb assembly.
On the receiving side, Patent Application DE 19723103.9, for example, discloses a differential receiver. Such a receiver contains a decoder that is synchronized to the coder of the transmitter, the optical signals of which it wants to or is authorized to receive. In particular, the simultaneous activity of a plurality of transmitters in the optical transmission leads to side-to-side crosstalk in the receiver of the optical signals from the transmitters. The signals to be detected, therefore, also contain portions of optical signals from other transmitters which are experienced as interference. The prior art discloses ways to suppress this interference by compensation in the differential receiver. Such a receiver with compensation of the two signal branches is disclosed, for example, in Patent Application DE 19748756.4. In the optical differential receiver for frequency-coded optical CDMA
systems disclosed in this patent, it is necessary, within the electrical modulation bandwidth, e.g., 108 MHz for a n~155 MBit/s system, to guarantee the synchronization of the two receiver arms with regard to the amplitude and phase shifts of the signals of less than 0.1 dB and < 10 ps for all frequencies. It is thereby possible to achieve a bit error rate of < 10-9, for example. The requirements for such an optical differential amplifier, however, increase with the number of simultaneous transmitters in the network, so that it becomes increasingly more difficult to connect much more than 8 transmitters to the network. For large numbers of transmitters, therefore, the concept of the differential receiver must be discarded. Nevertheless, the receiver claimed by the invention can be used to achieve the necessary suppression of the side-to-side crosstalk of the channels that are not to be received.
The receiver claimed by the invention with the characterizing features disclosed in Claim 1 has the advantage over similar devices of the prior art that a high number of transmitters can be operated in a transmission system. The sensitivity to crosstalk is largely eliminated by modulation of the optical signal.
Advantageous refinements and improvements of the receiver disclosed in the independent claim are possible with the features disclosed in the subclaims.
It is advantageous if, in the receiver, a high suppression of the side-to-side crosstalk of the other channels is guaranteed by a modulation of the filter characteristic of the optical filter. The modulation of the optical filter is advantageously performed at a high frequency, and the modulated signal is evaluated with a microwave detector.
In one advantageous embodiment, the optical decoder is a Mach-Zehnder filter. Another embodiment uses a Fabry-Perot filter as the optical decoder. The optical filter is advantageously connected directly with a microwave generator. The modulation frequency is thereby always greater than the frequency of the bit rate of the data transmission.
One exemplary embodiment of the invention is illustrated in the accompanying drawing and is explained in greater detail below.
The signal input (1) is connected with an optical filter (3), which is in turn connected with a microwave oscillator (7). The optical output of the optical filter (3) is connected with the input of a photodetector (4), the output of which is connected to an amplifier (5). The output signal of the amplifier is transmitted to a microwave detector (6), at which the electrical output data (2) are once again available. Figure 2 shows a detail from the synchronization curve of the optical filter (3). Plotted along the x-axis is the normalized inverse FSR (Free Spectral Range) of the receiver filter, and the y-axis represents the optical output power of the optical filter (3). By means of the microwave oscillator (7), the free spectral range (FSR) of the optical filter (3) at a frequency f0 is modulated by a few fractions, for example 10-5. The modulation of the optical filter (3) can thereby be performed, for example, by means of an optical phase modulator. The modulation frequency f0 must thereby be greater than the bit rate fdata of the data to be detected.
The shift is large enough that it runs through at least one maximum and one minimum of the synchronization curve of the optical filter (3). The output signal to the photo diode (5) is then amplitude-modulated at a frequency fl > f0, whereby contributions from upper harmonics are ignored. The exact value of fl depends on the shift of the FSR
modulation, and can be set using the latter. The frequency subcarrier at fl is still modulated with the data signals, so that a narrow band amplifier with a bandwidth of 2*~f around a central frequency of fl is required for the electrical amplification. For example, ~f - 0.7*fdata is sufficient as the bandwidth for the amplifier. The retransformation of the subcarrier signal into the base band is done, for example, using a microwave detector. The transmitters to be suppressed, which are received in the form of crosstalk between the channels in the receivers, do not make any contribution, because for it the corresponding synchronization curve is a constant, i.e., it does not depend on the precision adjustment of the free spectral range of the optical filter (3), and therefore does not generate any microwave signal in the photo diode, either.
These same advantages can be achieved by influencing the optical signal on the transmission side so that the transmitted frequency polarization comb assembly is subjected to a fitter. It is thereby possible, as described in Patent Application DE 19822616.0, to influence the optical transmission signal and to evaluate the electrical signal on the receiver side by the use of the microwave detector. The fitter can thereby be created on the transmitter side by modulation of the carrier frequency of the frequency polarization comb assembly, or by a modulation of the FSR of the transmitter filter.
The same advantages can be achieved by shifting the receiving spectrum to the transmitter side instead of the FSR of the optical filter. All the variants with an imposed optical fitter must be realized at a frequency f0 that is greater than the bit rate fdata~
The signal input (1) is connected with an optical filter (3), which is in turn connected with a microwave oscillator (7). The optical output of the optical filter (3) is connected with the input of a photodetector (4), the output of which is connected to an amplifier (5). The output signal of the amplifier is transmitted to a microwave detector (6), at which the electrical output data (2) are once again available. Figure 2 shows a detail from the synchronization curve of the optical filter (3). Plotted along the x-axis is the normalized inverse FSR (Free Spectral Range) of the receiver filter, and the y-axis represents the optical output power of the optical filter (3). By means of the microwave oscillator (7), the free spectral range (FSR) of the optical filter (3) at a frequency f0 is modulated by a few fractions, for example 10-5. The modulation of the optical filter (3) can thereby be performed, for example, by means of an optical phase modulator. The modulation frequency f0 must thereby be greater than the bit rate fdata of the data to be detected.
The shift is large enough that it runs through at least one maximum and one minimum of the synchronization curve of the optical filter (3). The output signal to the photo diode (5) is then amplitude-modulated at a frequency fl > f0, whereby contributions from upper harmonics are ignored. The exact value of fl depends on the shift of the FSR
modulation, and can be set using the latter. The frequency subcarrier at fl is still modulated with the data signals, so that a narrow band amplifier with a bandwidth of 2*~f around a central frequency of fl is required for the electrical amplification. For example, ~f - 0.7*fdata is sufficient as the bandwidth for the amplifier. The retransformation of the subcarrier signal into the base band is done, for example, using a microwave detector. The transmitters to be suppressed, which are received in the form of crosstalk between the channels in the receivers, do not make any contribution, because for it the corresponding synchronization curve is a constant, i.e., it does not depend on the precision adjustment of the free spectral range of the optical filter (3), and therefore does not generate any microwave signal in the photo diode, either.
These same advantages can be achieved by influencing the optical signal on the transmission side so that the transmitted frequency polarization comb assembly is subjected to a fitter. It is thereby possible, as described in Patent Application DE 19822616.0, to influence the optical transmission signal and to evaluate the electrical signal on the receiver side by the use of the microwave detector. The fitter can thereby be created on the transmitter side by modulation of the carrier frequency of the frequency polarization comb assembly, or by a modulation of the FSR of the transmitter filter.
The same advantages can be achieved by shifting the receiving spectrum to the transmitter side instead of the FSR of the optical filter. All the variants with an imposed optical fitter must be realized at a frequency f0 that is greater than the bit rate fdata~
As the microwave detector, an envelope curve detector can be used on the receiver side, although it is also possible to perform an evaluation by mans of a coherent hete-rodyning.
Claims (10)
1. Receiver for use in a transmission system for spectral-coded data with periodic optical filters (3), light-sensitive detectors (4) and electrical signal amplifiers (5), characterized by the fact that an input signal can be evaluated that is modulated on the transmitter or receiver side by an impressed fitter of the carrier frequency of the frequency polarization comb assembly or by the fitter of the frequency intervals of the frequency polarization comb assembly.
2. Receiver for use in a transmission system for spectral-coded data with periodic optical filters (3), light-sensitive detectors (4) and electrical signal amplifiers (5), characterized by the fact that the filter characteristic of the at least one optical filter (3) can be modulated at a frequency f 0 and that the electrical signal obtained by means of the light-sensitive detector (4) is applied to a microwave detector (6).
3. Receiver as claimed in one of the preceding claims, characterized by the fact that the optical filter is a Mach-Zehnder filter.
4. Receiver as claimed in one of the preceding claims, characterized by the fact that the optical filter is a Fabry-Perot filter.
5. Receiver as claimed in one of the preceding claims, characterized by the fact that the optical filter (3) is connected to a microwave generator (7).
6. Receiver as claimed in one of the preceding claims, characterized by the fact that the frequency of the modulation is greater than the frequency of the bit rate of the data transmission.
7. Receiver as claimed in one of the preceding claims, characterized by the fact that the modulation shift is at least large enough that it runs through a maximum and a minimum of the synchronization curve of the optical filter.
8. Method for the reception of spectral-coded optical signals in a CDMA transmission system, whereby an optical signal is decoded, converted into an electrical signal and amplified, characterized by the fact that the optical signal is modulated by modulation of the synchronization of the optical decoder at a first frequency, the modulated signal is converted in a light-sensitive detector into an electrical signal of a second frequency, and this electrical signal is transformed back into the base band in a detector.
9. Method for the reception of spectral-coded optical signals in a CDMA transmission system, whereby an optical signal is decoded, converted into an electrical signal and amplified, characterized by the fact that the optical signal is modulated by modulation in the transmitter, the modulated signal is converted in a light-sensitive detector into an electrical signal of a second frequency, and this electrical signal is transformed back into the base band in a detector.
10. Method as claimed in Claim 8, characterized by the fact that the electrical signal is electrically amplified before transformation back into the base band.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19833549.0 | 1998-07-25 | ||
| DE19833549A DE19833549A1 (en) | 1998-07-25 | 1998-07-25 | Receiver for use in a transmission system for spectrally coded data and a method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2278445A1 true CA2278445A1 (en) | 2000-01-25 |
Family
ID=7875318
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002278445A Abandoned CA2278445A1 (en) | 1998-07-25 | 1999-07-23 | Receiver for use in a transmission system for spectral-coded data as well as a method |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US6594056B1 (en) |
| EP (1) | EP0977383A3 (en) |
| JP (1) | JP2000059340A (en) |
| CA (1) | CA2278445A1 (en) |
| DE (1) | DE19833549A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1286488A1 (en) | 2001-08-20 | 2003-02-26 | Alcatel | Optical code converter |
| KR100827147B1 (en) * | 2001-10-19 | 2008-05-02 | 삼성전자주식회사 | Transceiver and method for re-transmission and decording of high speed data in cdma mobile communication system |
Family Cites Families (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4131792A (en) * | 1978-01-24 | 1978-12-26 | The United States Of America As Represented By The Secretary Of The Air Force | Fabry-Perot diplexer |
| DE3416493A1 (en) * | 1984-05-04 | 1985-11-07 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | OPTICAL RECEIVING DEVICE |
| US4703474A (en) * | 1986-02-28 | 1987-10-27 | American Telephone And Telegraph Company, At&T Bell Laboratories | Spread spectrum code-division-multiple-access (SS-CDMA) lightwave communication system |
| JP3070610B2 (en) * | 1989-07-28 | 2000-07-31 | 株式会社日立製作所 | Optical tuning method, optical tuning device, and optical frequency multiplex transmission device |
| JPH0385834A (en) * | 1989-08-30 | 1991-04-11 | Hitachi Ltd | Optical frequency multiplexer and optical frequency multiplex transmitter |
| US5105295A (en) * | 1990-01-03 | 1992-04-14 | Gte Laboratories Incorporated | Four level FSK optical signal transmission with optical decoding and direct detection |
| US5159481A (en) * | 1990-09-14 | 1992-10-27 | Bell Communications Research, Inc. | Polarization scrambler for polarization-sensitive optical devices |
| EP0489444B1 (en) * | 1990-12-06 | 1999-04-07 | Nec Corporation | Method for transmission and receipt of coherent light signals |
| JP3226067B2 (en) * | 1992-10-03 | 2001-11-05 | キヤノン株式会社 | Optical communication method and optical communication system |
| US5373389A (en) * | 1992-10-27 | 1994-12-13 | General Instrument Corporation | Method for linearizing an unbalanced Mach Zehnder optical frequency discriminator |
| DE4326522A1 (en) * | 1993-08-06 | 1995-02-09 | Siemens Ag | Programmable optical filter and optical circuit arrangement |
| JP3303515B2 (en) * | 1994-03-18 | 2002-07-22 | キヤノン株式会社 | Optical communication system and optical communication system using the same |
| USH1702H (en) * | 1995-01-06 | 1998-01-06 | Esman; Ronald D. | Wideband fiber-optic signal processor |
| DE19605567A1 (en) * | 1996-02-15 | 1997-08-21 | Sel Alcatel Ag | Optical frequency-coded CDMA transmission system and optical receiver therefor |
| CA2206945A1 (en) * | 1996-06-03 | 1997-12-03 | Tadashi Koga | Optical receiver board, optical wavelength-tuning filter module used foroptical receiver board, and actuator for optical wavelength-tuning filter module |
| DE19649085A1 (en) * | 1996-11-27 | 1998-05-28 | Alsthom Cge Alcatel | Transmitting / receiving device and method for transmitting broadband signals and transmitting / receiving device for receiving broadband signals |
-
1998
- 1998-07-25 DE DE19833549A patent/DE19833549A1/en not_active Withdrawn
-
1999
- 1999-07-16 EP EP99440199A patent/EP0977383A3/en not_active Withdrawn
- 1999-07-21 JP JP11206169A patent/JP2000059340A/en active Pending
- 1999-07-23 CA CA002278445A patent/CA2278445A1/en not_active Abandoned
- 1999-07-23 US US09/359,386 patent/US6594056B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0977383A2 (en) | 2000-02-02 |
| US6594056B1 (en) | 2003-07-15 |
| DE19833549A1 (en) | 2000-01-27 |
| EP0977383A3 (en) | 2004-03-03 |
| JP2000059340A (en) | 2000-02-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |