CN112731476B - GPS satellite M code signal demodulation method based on short code despreading and timing recovery combination - Google Patents
GPS satellite M code signal demodulation method based on short code despreading and timing recovery combination Download PDFInfo
- Publication number
- CN112731476B CN112731476B CN202011149741.8A CN202011149741A CN112731476B CN 112731476 B CN112731476 B CN 112731476B CN 202011149741 A CN202011149741 A CN 202011149741A CN 112731476 B CN112731476 B CN 112731476B
- Authority
- CN
- China
- Prior art keywords
- code
- signal
- gps satellite
- signals
- despreading
- 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.)
- Active
Links
Classifications
-
- 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
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/30—Acquisition or tracking or demodulation of signals transmitted by the system code related
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention provides a GPS satellite M-code signal demodulation method based on combination of short code despreading and timing recovery, which utilizes the mutual promotion relation of short code despreading and timing recovery, can effectively reduce the signal-to-noise ratio threshold of demodulation, equivalently reduces the antenna caliber and saves the construction cost. Firstly, acquiring carrier frequency and carrier phase of GPS satellite navigation signals through a typical carrier estimation method, carrying out carrier recovery and IQ separation, and further realizing extraction of GPS M code signals through band-pass filtering; and then short code decoding is carried out on the GPS M code signal to obtain coding gain, blind processing is adopted for timing synchronization for the first time on the basis, the M code stream is obtained after judgment, the information of the M code signal is contained, and the information is fed back to the front end to carry out timing synchronization operation on the signal again, so that the timing synchronization precision can be improved.
Description
Technical Field
The invention belongs to the technical field of satellite system monitoring and maintenance, and particularly relates to a GPS satellite M code signal demodulation method based on combination of short code despreading and timing recovery.
Background
Along with the modernization of GPS satellites, the M codes of a GPS satellite navigation system have been initially completed into a full-sphere networking, and corresponding M code navigation receivers have been put into practical use. Because the M code signal in the GPS signal is overlapped with the C/A code and the P code, the local M code signal is constructed mainly by the GPS signal blind demodulation method under the condition that the code pattern and the encryption mode of the M code cannot be acquired, so as to construct the GPS M code receiving equipment. When the M code signal is subjected to blind demodulation, a large-caliber high-gain antenna is mainly adopted to receive GPS satellite navigation signals at present so as to ensure demodulation performance. However, the existing large-caliber antenna has higher construction and maintenance cost, needs a demodulation technology of GPS signals with low signal to noise ratio, reduces the signal to noise ratio threshold of demodulation, equivalently reduces the caliber of the antenna, and saves construction cost.
Disclosure of Invention
In order to solve the technical problems, the invention provides a GPS satellite M-code signal demodulation method based on combination of short code despreading and timing recovery, which utilizes the mutual promotion relation of the short code despreading and the timing recovery, can effectively reduce the signal-to-noise ratio threshold of demodulation, equivalently reduces the antenna caliber and saves the construction cost.
In order to achieve the above purpose, the invention provides a GPS satellite M code signal demodulation method based on short code despreading and timing recovery, which comprises the following steps:
step 1, performing short code decoding on a GPS satellite M code signal to obtain coding gain and an M code oversampling signal;
step 2, performing timing synchronization on the M-code oversampling signals by adopting a blind processing mode to obtain M-code soft symbols;
step 3, judging the current M code soft symbol to obtain an M code stream;
step 4, reconstructing an M code oversampling signal by using the M code stream obtained in the step 3 to obtain a pseudo reference signal, and carrying out timing synchronization on the M code oversampling signal obtained in the step 1 by using the pseudo reference signal to obtain an M code soft symbol;
and 5, repeating the steps 3-4, and stopping the operation when the M code stream obtained by judgment is not changed any more, so as to finish demodulation.
In the step 1, the specific manner of obtaining the M-code oversampling signal is as follows:
performing data rate conversion on the GPS satellite M code signal to obtain a BOC modulation M code signal with 4 times of oversampling rate;
and carrying out serial-parallel conversion on the BOC modulation M code signals to obtain 4 paths of signal subsequences, and respectively carrying out weighted combination on the 4 paths of signal subsequences by using +1, -1, +1 and-1 by utilizing the known M code BOC modulation information to obtain 1 path of M code oversampling signals.
In the step 1, the acquisition mode of the GPS satellite M-code signal is as follows:
sampling GPS satellite navigation signals; and C/A code signal stripping and P code signal stripping are carried out on the sampled GPS satellite navigation signals, so as to obtain GPS satellite M code signals.
The specific mode for stripping the C/A code signal of the sampled GPS satellite navigation signal is as follows:
the carrier frequency and the carrier phase of the GPS satellite navigation signal are obtained, the carrier frequency and the carrier phase are utilized to complete carrier recovery of the GPS satellite navigation signal, the separation of the orthogonal component and the in-phase component of the signal is completed through orthogonal processing, and the C/A code signal is stripped to obtain the P code and M code branch signals.
And stripping the P code signals in the P code and M code branch signals through band-pass filtering to obtain GPS satellite M code signals.
The specific mode for sampling the GPS satellite navigation signals is as follows:
and receiving GPS satellite navigation signals by using an antenna, converting the GPS satellite navigation signals to intermediate frequency, and then carrying out AD sampling.
The beneficial effects are that:
according to the invention, the mutual promotion relation of short code despreading and timing recovery is utilized, short code despreading is firstly carried out on an oversampled M code signal, on the basis of obtaining coding gain, blind processing is adopted for timing synchronization on the M code signal for the first time, and after judgment, an M code stream is obtained, and the M code stream contains information of the M code signal, so that the system performance under low signal-to-noise ratio can be improved; by adopting an iterative processing mode, the information obtained by demodulating the M-code signal is fed back to the front end, and the information is fed back to the front end as an aid to carry out timing synchronization operation on the signal again, so that the timing synchronization precision can be improved, the demodulation quality of the GPS M-code signal can be effectively improved, the signal-to-noise ratio threshold can be effectively reduced under the condition of obtaining the same demodulation error rate, the caliber of a receiving antenna is reduced, and the system construction and maintenance cost is saved.
Drawings
FIG. 1 is a schematic diagram of the implementation process of a GPS M-code signal demodulation method based on joint processing of short code despreading and timing recovery;
FIG. 2 is a block diagram of a joint process based on short code despreading and timing recovery according to the present invention;
FIG. 3 is a schematic diagram of a BOC modulated M-code oversampling signal obtained in step 4 of the present invention;
FIG. 4 is a schematic diagram of the step 5 signal subsequence weighting and combining before and after the step of the present invention;
fig. 5 is a diagram of a typical M-code signal blind demodulation structure in the prior art.
Detailed Description
The present invention will be described in detail with reference to the following examples.
From the consideration of the relevance of each step of the M code signal demodulation processing, namely the relevance of different stages of the signal demodulation processing, the information recovery of the received data is obviously mutually influenced by different processing stages, for example, the advantages and disadvantages of timing synchronization performance directly influence the decoding effect of the back end and influence the final symbol judgment result. The comprehensive consideration and the combined treatment are carried out on the treatment processes, so that better system performance can be obtained.
The invention obtains the carrier frequency and carrier phase of GPS satellite navigation signals through a typical carrier estimation technology, carries out carrier recovery and IQ separation, further realizes the extraction of GPS satellite M code signals through band-pass filtering, then carries out short code decoding on the GPS satellite M code signals to obtain coding gain, carries out timing synchronization and M code judgment on the basis, realizes the extraction of M code streams, and is different from the prior demodulation method of timing synchronization and BOC decoding (figure 5). The invention is based on the combination of short code despreading and timing recovery, firstly carries out short code decoding on the oversampled BOC modulation signal, can obtain coding gain, carries out subsequent processing on the basis, and can improve the system performance under low signal-to-noise ratio, and particularly comprises the following steps:
step 1, performing short code decoding on a GPS satellite M code signal to obtain coding gain and an M code oversampling signal;
step 2, performing timing synchronization on the M-code oversampling signals by adopting a blind processing mode to obtain M-code soft symbols;
step 3, judging the current M code soft symbol to obtain an M code stream;
step 4, reconstructing an M code oversampling signal by using the M code stream obtained in the step 3 to obtain a pseudo reference signal, and carrying out timing synchronization on the M code oversampling signal obtained in the step 1 by using the pseudo reference signal to obtain an M code soft symbol;
and 5, repeating the steps 3-4, and stopping the operation when the M code stream obtained by judgment is not changed any more, so as to finish demodulation.
In step 1, the specific manner of obtaining the M-code oversampling signal is as follows:
performing data rate conversion on the GPS satellite M-code signal to obtain a BOC modulation M-code signal (figure 3) with 4 times of oversampling rate, wherein the sampling rate is 81.84MHz in the embodiment;
performing serial-parallel conversion on the obtained BOC modulation M code signal according to the diagram shown in fig. 4 to obtain 4 paths of signal subsequences with the sampling rate of 20.46MHz, and respectively performing weighted combination on the 4 paths of subsequences by using +1, -1, +1 and-1 by utilizing the known M code BOC modulation information to obtain 1 path of M code oversampling signals;
the acquisition mode of the GPS satellite M code signal is as follows:
receiving and digitally sampling GPS satellite navigation signals;
carrying out carrier frequency and carrier phase estimation on the sampled GPS satellite navigation signals; the carrier frequency and the carrier phase are utilized to complete carrier recovery of GPS satellite navigation signals, IQ separation of C/A code signals and P code and M code signals is completed, and P code and M code branch signals are obtained; carrying out band-pass filtering on the obtained P code and M code branch signals, and stripping the P code signals to obtain GPS satellite M code signals;
the M code soft symbol obtained after primary timing synchronization is judged, and the M code stream rate obtained by judgment is 5.115Mbps; and reconstructing the M code signal by using the obtained M code stream to obtain the sampling rate of 20.46MHz.
In the embodiment, an antenna is used for receiving a GPS satellite navigation radio frequency signal, the central frequency point of the signal is 1575.42MHz, and AD sampling is performed after the radio frequency signal is changed to an intermediate frequency.
Separation (IQ separation) of the quadrature component and the in-phase component of the signal is completed by quadrature processing, and the C/a code signal is stripped.
And designing a band-pass filter according to the difference between the P code and M code spectrums, and stripping the P code signals.
The present invention is capable of other and further embodiments and its several details are capable of modification and variation in light of the present invention, as will be apparent to those skilled in the art, without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (6)
1. A GPS satellite M code signal demodulation method based on short code despreading and timing recovery is characterized by comprising the following steps:
step 1, performing short code decoding on a GPS satellite M code signal to obtain coding gain and an M code oversampling signal;
step 2, performing timing synchronization on the M-code oversampling signals by adopting a blind processing mode to obtain M-code soft symbols;
step 3, judging the current M code soft symbol to obtain an M code stream;
step 4, reconstructing an M code oversampling signal by using the M code stream obtained in the step 3 to obtain a pseudo reference signal, and carrying out timing synchronization on the M code oversampling signal obtained in the step 1 by using the pseudo reference signal to obtain an M code soft symbol;
and 5, repeating the steps 3-4, and stopping the operation when the M code stream obtained by judgment is not changed any more, so as to finish demodulation.
2. The method for demodulating the M-code signal of the GPS satellite based on the combination of short code despreading and timing recovery according to claim 1, wherein in the step 1, the specific manner of obtaining the M-code oversampled signal is as follows:
performing data rate conversion on the GPS satellite M code signal to obtain a BOC modulation M code signal with 4 times of oversampling rate;
and carrying out serial-parallel conversion on the BOC modulation M code signals to obtain 4 paths of signal subsequences, and respectively carrying out weighted combination on the 4 paths of signal subsequences by using +1, -1, +1 and-1 by utilizing the known M code BOC modulation information to obtain 1 path of M code oversampling signals.
3. The method for demodulating the M-code signal of the GPS satellite based on the combination of short code despreading and timing recovery according to claim 1, wherein in the step 1, the M-code signal of the GPS satellite is obtained by:
sampling GPS satellite navigation signals; and C/A code signal stripping and P code signal stripping are carried out on the sampled GPS satellite navigation signals, so as to obtain GPS satellite M code signals.
4. The method for demodulating the M-code signal of the GPS satellite based on the combination of short code despreading and timing recovery as set forth in claim 3, wherein the specific way of performing C/a code signal stripping on the sampled GPS satellite navigation signal is as follows:
the carrier frequency and the carrier phase of the GPS satellite navigation signal are obtained, the carrier frequency and the carrier phase are utilized to complete carrier recovery of the GPS satellite navigation signal, the separation of the orthogonal component and the in-phase component of the signal is completed through orthogonal processing, and the C/A code signal is stripped to obtain the P code and M code branch signals.
5. The method for demodulating a GPS satellite M-code signal based on a combination of short code despreading and timing recovery according to claim 4, wherein the P-code signal in the P-code and M-code branch signals is stripped by bandpass filtering to obtain a GPS satellite M-code signal.
6. A method for demodulating a GPS satellite M-code signal based on a combination of short code despreading and timing recovery as set forth in claim 3, wherein the specific way of sampling a GPS satellite navigation signal is:
and receiving GPS satellite navigation signals by using an antenna, converting the GPS satellite navigation signals to intermediate frequency, and then carrying out AD sampling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011149741.8A CN112731476B (en) | 2020-10-23 | 2020-10-23 | GPS satellite M code signal demodulation method based on short code despreading and timing recovery combination |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011149741.8A CN112731476B (en) | 2020-10-23 | 2020-10-23 | GPS satellite M code signal demodulation method based on short code despreading and timing recovery combination |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112731476A CN112731476A (en) | 2021-04-30 |
| CN112731476B true CN112731476B (en) | 2023-09-08 |
Family
ID=75597297
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011149741.8A Active CN112731476B (en) | 2020-10-23 | 2020-10-23 | GPS satellite M code signal demodulation method based on short code despreading and timing recovery combination |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112731476B (en) |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5712869A (en) * | 1994-11-22 | 1998-01-27 | Samsung Electronics Co., Ltd. | Data transmitter and receiver of a spread spectrum communication system using a pilot channel |
| FR2783929A1 (en) * | 1998-09-25 | 2000-03-31 | Sextant Avionique | PROCESS AND DEVICE FOR PROCESSING IN RECEPTION OF A GPS SATELLITE L2 SIGNAL |
| US6750816B1 (en) * | 2003-02-12 | 2004-06-15 | Novatel, Inc. | Integrated GPS-inertial system |
| US7266140B1 (en) * | 1999-10-15 | 2007-09-04 | Sony Corporation | GPS positioning method and GPS reception apparatus |
| JP2008252162A (en) * | 2007-03-29 | 2008-10-16 | Mitsubishi Electric Corp | Spread signal receiver |
| CN103353599A (en) * | 2012-06-06 | 2013-10-16 | 东莞市泰斗微电子科技有限公司 | Method for processing Beidou navigation satellite signals, chip and module |
| CN106842263A (en) * | 2017-01-21 | 2017-06-13 | 中国人民解放军信息工程大学 | Based on the satellite navigation method that navigation signal space time processing is combined with vector tracking |
| CN111183750B (en) * | 2015-07-17 | 2017-11-10 | 中国电子科技集团公司第五十四研究所 | Long-short code combined spread spectrum system unmanned aerial vehicle data link receiver |
| CN110208832A (en) * | 2019-07-02 | 2019-09-06 | 中国电子科技集团公司第五十四研究所 | A kind of multiplexing navigation signal pseudo-code extracting method |
-
2020
- 2020-10-23 CN CN202011149741.8A patent/CN112731476B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5712869A (en) * | 1994-11-22 | 1998-01-27 | Samsung Electronics Co., Ltd. | Data transmitter and receiver of a spread spectrum communication system using a pilot channel |
| FR2783929A1 (en) * | 1998-09-25 | 2000-03-31 | Sextant Avionique | PROCESS AND DEVICE FOR PROCESSING IN RECEPTION OF A GPS SATELLITE L2 SIGNAL |
| US7266140B1 (en) * | 1999-10-15 | 2007-09-04 | Sony Corporation | GPS positioning method and GPS reception apparatus |
| US6750816B1 (en) * | 2003-02-12 | 2004-06-15 | Novatel, Inc. | Integrated GPS-inertial system |
| JP2008252162A (en) * | 2007-03-29 | 2008-10-16 | Mitsubishi Electric Corp | Spread signal receiver |
| CN103353599A (en) * | 2012-06-06 | 2013-10-16 | 东莞市泰斗微电子科技有限公司 | Method for processing Beidou navigation satellite signals, chip and module |
| CN111183750B (en) * | 2015-07-17 | 2017-11-10 | 中国电子科技集团公司第五十四研究所 | Long-short code combined spread spectrum system unmanned aerial vehicle data link receiver |
| CN106842263A (en) * | 2017-01-21 | 2017-06-13 | 中国人民解放军信息工程大学 | Based on the satellite navigation method that navigation signal space time processing is combined with vector tracking |
| CN110208832A (en) * | 2019-07-02 | 2019-09-06 | 中国电子科技集团公司第五十四研究所 | A kind of multiplexing navigation signal pseudo-code extracting method |
Non-Patent Citations (1)
| Title |
|---|
| 王庆民 ; 封欣 ; 伍蔡伦 ; 陆明泉 ; .BOC卫星导航信号直接解调的方法及实现.清华大学学报(自然科学版)网络.预览.2009,(04),570-573. * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112731476A (en) | 2021-04-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112671446B (en) | Demodulation device suitable for high-orbit inter-satellite link | |
| CN105763498A (en) | All-digital receiving method for satellite-borne AIS | |
| CN109495237B (en) | Multi-rate demodulation device based on sampling point selection | |
| CN108183877B (en) | Multi-tone frequency modulation signal demodulation method based on FPGA | |
| US6868129B2 (en) | Demodulator for a radio receiver and method of operation | |
| CN110208832B (en) | Method for extracting pseudo code of multiplex navigation signal | |
| CN102025669A (en) | Short-wave data transmission method based on dual multisystem quasi-orthogonal spread-spectrum composite phase modulation | |
| CN102932032A (en) | Broadband wireless communication and range location integrated system and method | |
| WO2005055449A1 (en) | Bandpass sampling receiver and the sampling method | |
| EP1993213A1 (en) | Spread baseband injected pilot carrier | |
| CN109450828B (en) | Signal processing chip | |
| CN112731476B (en) | GPS satellite M code signal demodulation method based on short code despreading and timing recovery combination | |
| CN111158017B (en) | Method for assisting in synchronizing data components of pilot frequency components of L1C/B1C navigation signals | |
| CN1845543A (en) | Non-coherent digital demodulation device for RDS signal | |
| CN115685267B (en) | Rapid telegraph text synchronization and decoding method for low-orbit constellation navigation enhancement signal | |
| CN110460367B (en) | Method for receiving low-orbit communication satellite signal of swan goose | |
| US11841442B2 (en) | Doppler tracking for signals of opportunity using rate-line detection | |
| CN110636022A (en) | Signal receiving method and device for reducing data demodulation threshold | |
| CN114157313B (en) | Baseband circuit structure and method for receiving GLONASS three-frequency new system signals | |
| CN106850478B (en) | Data demodulation and synchronization method for automatic ship identification system | |
| CN112600784B (en) | Large frequency offset bit synchronization method based on quadratic differential correlation | |
| US20050254593A1 (en) | Doppler aided detection, processing and demodulation of multiple signals | |
| CN111868545B (en) | Satellite communication navigation signal generation method and device and satellite communication navigation signal receiving method and device | |
| CN114124197A (en) | Satellite-borne AIS signal demodulation method | |
| CN112578412A (en) | Capturing method compatible with B1C signal and B2a signal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |