CN101666869B - Method and device for secondary capturing weak satellite navigation signals - Google Patents
Method and device for secondary capturing weak satellite navigation signals Download PDFInfo
- Publication number
- CN101666869B CN101666869B CN2009101529435A CN200910152943A CN101666869B CN 101666869 B CN101666869 B CN 101666869B CN 2009101529435 A CN2009101529435 A CN 2009101529435A CN 200910152943 A CN200910152943 A CN 200910152943A CN 101666869 B CN101666869 B CN 101666869B
- Authority
- CN
- China
- Prior art keywords
- module
- data
- frequency
- coherent integration
- group
- 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
Images
Landscapes
- Position Fixing By Use Of Radio Waves (AREA)
Abstract
The invention discloses a method and a device for secondary capturing weak satellite navigation signals. A capturing module of a satellite navigation receiver finishes more coarse evaluation on a pseudo code phase and Doppler frequency shift. In high sensitivity satellite navigation receiver, long-time coherent integral is carried out to improve tracking sensitivity, which requires knowing the overturn position of navigation message bit and smaller surplus Doppler frequency shift. After capturing, secondary capturing is performed on data output by a correlation tracker, secondary search is performed on frequency points in the surplus frequency shift range to find the initial positions of the overturn position and secondary coding of the message bit. Frequency shift compensation, correlation integral and square are performed on data output by the correlation tracker after target frequency points and the initial positions of the overturn position and the secondary coding of the modulating message data are found, and a spectrum analysis method is used for performing refined evaluation on the surplus frequency shift after frequency shift compensation. The invention is suitable for the satellite navigation receivers of multiple systems such as GPS, GLONASS and the like.
Description
Technical field
The present invention relates to a kind of secondary capturing weak satellite navigation signals method and apparatus.
Background technology
Along with the development of radiotelegraphy and space technology, in the past 30 years of satellite-based navigator fix technology have obtained developing rapidly.The NAVSTAR of having built up at present and having come into operation has GPS (GPS) and GPS (GLONASS); Have more NAVSTAR future and come into operation, like Galileo (Galileo) satellite navigation system and the Big Dipper (BeiDou) satellite navigation system; These systems are generically and collectively referred to as the GNSS system sometimes.Navigation neceiver is through receiving the signal of abundant satellite, and picked up signal travel-time information and satellite position information obtain the position, time, speed of receiver etc. according to these information calculations.
In order to resolve by navigator fix, navigation neceiver must receive the signal of at least 4 satellites; Navigation neceiver generally has a plurality of parallel receiving cables, and each passage receives the signal of a satellite.Navigation neceiver is at first caught satellite-signal through these parallel channels, and acquisition procedure is the search procedure of a bidimensional in fact: pseudo-random code phases and Doppler frequency deviation.With GPS is example, and every different length of satellites transmits is 1023, and the cycle is 1 millisecond a pseudo-random sequence; Have relative motion in the middle of satellite and the receiver, thereby Doppler frequency also is unknown.When catching; Navigation neceiver produces different local pseudo-random sequence and carrier frequencies to different satellites and carries out relevant with input signal; When local pseudo-random sequence and list entries phase approximation synchronously and during the frequency approximately equal, relevant output valve can surpass detection threshold.Generally speaking, pseudo-random code phases search stepping is a half-chip when catching, and the Doppler frequency deviation stepping is (1/2T) Hz, and T is the coherent integration time, is generally 1 pseudo-random code cycle.Under weak signal environment,, carry out long-time coherent integration or non-coherent integration behind the related operation usually and obtain enough big processing gain in order accurately to catch chip phase and Doppler frequency deviation.
The navigation neceiver trapping module has been accomplished the rough estimate of signal, in order to obtain the accurate estimated value of pseudo-random code phases, carrier frequency/phase place, need carry out real-time follow-up to navigation signal.Tracking loop commonly used has delay lock loop (DLL), FLL (FLL) and phaselocked loop (PLL); Delay lock loop (DLL) is used for following the tracks of pseudo-random code phases, and FLL (FLL) and phaselocked loop (PLL) are used for following the tracks of carrier frequency and phase place.Under weak signal environment; It is narrow that above-mentioned loop bandwidth is provided with usually, and when loop bandwidth was narrow, the inherent spurious frequency deviation of initialization loop can not be too big; And remaining Doppler frequency deviation need carry out meticulous estimation to frequency deviation after catching completion not in the capture zone of loop.At outdoor open field, satellite-signal is more intense, is example with the C/A sign indicating number of GPS, the satellite-signal carrier-to-noise ratio (C/N that navigation neceiver receives
0) be approximately 44dB/Hz, such signal intensity, the intact data of despreading are used for following the tracks of enough; Under weak signal environment, need carry out long-time coherent integration obtaining sufficiently high signal to noise ratio (S/N ratio) to the intact data of despreading, maximum coherence integral time is 20 milliseconds when modulating data is unknown, and need know the moment of modulating data upset.In some modern GNSS signals; Handling modulation has outside pseudo-random code, navigation message data, the carrier wave; Also there is secondary coding; As just modulating on the L5 frequency range of GPS the Neumann-Hoffman sign indicating number is arranged,, must accomplish the synchronous of secondary coding phase place in order to carry out long-time coherent integration and demodulation text.To the problems referred to above, satellite navigation receiver carries out pre-service to following the tracks of the correlator output data usually before loop tracks, obtain navigation message bit upturned position, the isoparametric estimated value of meticulous Doppler frequency deviation, with these estimated value initialization track loop.
Summary of the invention
The objective of the invention is to overcome the deficiency of prior art, a kind of secondary capturing weak satellite navigation signals method and apparatus is provided.
The method of secondary capturing weak satellite navigation signals comprises the steps:
1) under the control of control module, stores one group and follow the tracks of the correlator output data, the corresponding memory module of each tracing channel to memory module;
2) after the correlator output data is followed the tracks of in the memory module storage, control module control store module, frequency-variable module, matched filtering module and quadrature detector block will be caught the remaining Doppler frequency deviation scope in back and be divided into a plurality of frequencies; Frequency is searched for, found target frequency and modulation telegraph text data upturned position/secondary coding reference position;
3), the tracking correlator output data of storage is carried out the frequency deviation correction according to the target frequency; According to modulation telegraph text data upturned position/secondary coding reference position, to carrying out coherent integration through the revised data of overdeviation, coherent integration is carried out in same modulation telegraph text data, and the coherent integration time can divide exactly the modulated telegraph text data duration;
4) data after the coherent integration are carried out square operation, eliminate the influence of modulation text data polarity; Data behind the square operation obtain meticulousr frequency deviation with spectrum analysis, and spectrum analysis is carried out in the Frequency Estimation module.
Described under the control of control module, store one group of output data of following the tracks of correlator to memory module, the corresponding memory module step of each tracing channel comprises:
1) following the tracks of the correlator output data is complex signal, and the SI is 1 millisecond, and promptly sampling rate is 1KHz, and each modulation telegraph text data has 20 sampled points;
2) memory module storage data volume is 19+20*M, M＞0, the carrier-to-noise ratio decision that the value of M is estimated by acquisition phase;
3) when memory module storage data volume reaches requirement, send the secondary capturing enabling signal to control module.
After the correlator output data is followed the tracks of in described memory module storage, control module control store module, frequency-variable module, matched filtering module and quadrature detector block will be caught the remaining Doppler frequency deviation scope in back and be divided into a plurality of frequencies; Frequency is searched for, is found target frequency and modulation telegraph text data upturned position/secondary coding reference position step to comprise:
1) catch back residue Doppler frequency deviation scope for-(1/4T) Hz～+ (1/4T) Hz; T is the acquisition phase coherent integration time, is 1 millisecond, and residue Doppler frequency deviation scope is cut apart; Be spaced apart 1/ (2Td) Hz; Wherein Td is 20 milliseconds for the modulation telegraph text data duration, and N=Td/T+1 frequency arranged;
2) for each frequency, the local carrier module in the control module control of conversion module produces local carrier; Control module reads follows the tracks of the correlator output data in the memory module, carry out frequency conversion with the local carrier conjugate multiplication;
3) data after the frequency conversion are through the matched filtering module, and matched filter progression is 20, and tap coefficient is respectively: for the C/A coded signal of GPS be: 1,1,1,1,1,1,1,1,1,1,1; 1,1,1,1,1,1,1,1,1, for the quadrature branch signal of the L5 wave band of GPS be :-1 ,-1 ,-1 ,-1;-1,1 ,-1 ,-1,1,1 ,-1,1 ,-1,1 ,-1 ,-1; 1,1,1 ,-1, for the C/A sign indicating number of GLONASS be: 1,1,1,1,1,1,1,1; 1,1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1;
4) for each frequency, total 19+20*M the input data of matched filtering module, there is 20*M output data M＞0.Per 20 output datas are divided into 1 group, total M group data;
5) for each frequency, to the M group data delivery of matched filtering module output, the 0th group of No. 0 data, the 1st group of No. 0 data are up to No. 0 data addition of M-1 group behind the delivery; The 0th group of No. 1 data, the 1st group of No. 1 data are up to No. 1 data addition of M-1 group; And the like, the 0th group of No. 19 data, the 1st group of No. 19 data are up to No. 19 data additions of M-1 group; Common property is given birth to 20 non-coherent integration data;
6) N total 20*N non-coherent integration data of frequency, the non-coherent integration data are delivered to peak detection block; Peak detection block finds peak value; The peak value frequency points corresponding is exactly the target frequency; Being designated as the corresponding numbering of
peak value is exactly to modulate telegraph text data upturned position/secondary coding reference position, is designated as
Described for each frequency, total 19+20*M the input data of matched filtering module, there is 20*M output data M＞0.Per 20 output datas are divided into 1 group, and total M group data step comprises:
Preceding 19 data of 1) matched filtering module input data are filled up preceding 19 of matched filtering module shift register, and since the 20th input data, data of every input are just exported data, total 20*M output data, M＞0;
2) matched filtering module output data the 0th～19 is divided into the 0th group, and the 20th～39 is divided into the 1st group, and the like the 20*M-20～20*M-1 be divided into M-1 group.
Described according to the target frequency, the tracking correlator output data of storage is carried out the frequency deviation correction; Reference position according to modulation telegraph text data upturned position/secondary coding; To carrying out coherent integration through the revised data of overdeviation; Coherent integration is carried out in same modulation telegraph text data, and the coherent integration time can the modulated telegraph text data duration be divided exactly step and comprised:
1) according to the target frequency
control module controls the inverter module generation module generates local carrier frequency
corresponds to the complex frequency carrier signal.Control module reads the data in the memory module, with local complex carrier signal signal conjugate multiplication, accomplishes the frequency deviation correction;
2) begin to carry out from the individual data of frequency deviation revised
according to modulation telegraph text data upturned position/secondary coding reference position
coherent integration, the coherent integration time is 1 millisecond, 2 milliseconds, 4 milliseconds, 5 milliseconds or 10 milliseconds.
Data after the described coherent integration are carried out square operation, eliminate the influence of modulation text data polarity; Data behind the square operation obtain meticulousr frequency deviation with spectrum analysis, and spectrum analysis is carried out step and comprised in the Frequency Estimation module:
1) square operation is eliminated the variation of modulation text positive-negative polarity, and inherent spurious frequency deviation also becomes original twice simultaneously;
2) the inherent spurious frequency deviation scope is-1/ (4Td) Hz～1/ (4Td) Hz behind the compensate of frequency deviation, square frequency deviation region is doubled, and becomes-1/ (2Td) Hz～1/ (2Td) Hz; Td is 20 milliseconds, and frequency deviation region is-25Hz～25Hz behind the compensate of frequency deviation; Remaining Doppler frequency deviation behind the Spectral Analysis Method estimation compensate of frequency deviation.
The device of secondary capturing weak satellite navigation signals comprises like lower module: follow the tracks of correlator, memory module, frequency-variable module, matched filtering module, non-coherent integration module, peak detection block, coherent integration module, square module, Frequency Estimation module and control module; Following the tracks of correlator, memory module, frequency-variable module links to each other successively; Frequency-variable module links to each other with matched filtering module, coherent integration module respectively; Matched filtering module, non-coherent integration module, peak detection block link to each other successively; Coherent integration module, square module, Frequency Estimation module link to each other successively.Control module control is followed the tracks of the correlator output data and is stored memory module into, and memory module is sent the secondary capturing enabling signal to control module; Control module control store module output data, data find target frequency and modulation telegraph text data upturned position/secondary coding reference position through matched filtering module, non-coherent integration module, peak detection block; After finding the target frequency and modulating telegraph text data upturned position/secondary coding reference position; Control module control store module output data; Data are carried out the frequency deviation correction through frequency-variable module; Revised data are through coherent integration module, square module, and square module output data is carried out the fine estimation of frequency deviation through the Frequency Estimation module.
Described frequency-variable module comprises conjugate multiplication module, the local carrier module that is connected.
After the present invention stores one group of tracking correlator output data; Can carry out cutting apart once more of frequency deviation to following the tracks of the correlator output data with the mode that piece is handled; Through matched filtering module, non-coherent integration module and peak detection block, obtain the accumulated value of different frequent points and different modulating telegraph text data upturned position/secondary coding reference position; Detect the frequency that can find modulation telegraph text data upturned position/secondary coding reference position and search through peak value.According to searching to such an extent that frequency carries out the compensation of frequency deviation to the tracking correlator output data of storage; Data according to after finding modulation telegraph text data upturned position/secondary coding reference position to compensate of frequency deviation are carried out coherent integration, and coherent integration is carried out in same modulation telegraph text data.Coherent integration result square eliminates the influence of modulation text data polarity, then the estimated value through the meticulousr Doppler frequency deviation of the method acquisition of spectrum analysis.
Description of drawings
Fig. 1 is whole module of the present invention and connects block diagram;
Fig. 2 is the circuit block diagram of frequency-variable module among the present invention;
Fig. 3 is three kinds of coupling waveforms of matched filtering module among the present invention.
Embodiment
The method of secondary capturing weak satellite navigation signals comprises the steps:
1) under the control of control module, stores one group and follow the tracks of the correlator output data, the corresponding memory module of each tracing channel to memory module;
2) after the correlator output data is followed the tracks of in the memory module storage, control module control store module, frequency-variable module, matched filtering module and quadrature detector block will be caught the remaining Doppler frequency deviation scope in back and be divided into a plurality of frequencies; Frequency is searched for, found target frequency and modulation telegraph text data upturned position/secondary coding reference position;
3), the tracking correlator output data of storage is carried out the frequency deviation correction according to the target frequency; According to modulation telegraph text data upturned position/secondary coding reference position, to carrying out coherent integration through the revised data of overdeviation, coherent integration is carried out in same modulation telegraph text data, and the coherent integration time can divide exactly the modulated telegraph text data duration;
4) data after the coherent integration are carried out square operation, eliminate the influence of modulation text data polarity; Data behind the square operation obtain meticulousr frequency deviation with spectrum analysis, and spectrum analysis is carried out in the Frequency Estimation module.
Under the control of control module, store one group of output data of following the tracks of correlator to memory module, the corresponding memory module step of each tracing channel comprises:
1) following the tracks of the correlator output data is complex signal, and the SI is 1 millisecond, and promptly sampling rate is 1KHz, and each modulation telegraph text data has 20 sampled points, output data x
iExpression formula is:
x
i＝Ad
in
ie
j(2πiΔfT+θ)+N
i(1)
I is the data subscript in the formula (1), the amplitude of A expression signal, d
iExpression modulation telegraph text data, n
iThe secondary coding (secondary coding) that expression exists, Δ f is for having caught the residue Doppler frequency deviation, and T is 1 millisecond here for following the tracks of the correlator output time in SI, and θ is an initial phase, N
iBe noise; The upturned position of modulation telegraph text data and the reference position of secondary coding are identical.For the C/A sign indicating number of GPS, n
iPerseverance is a high level; N for the L5 wave band quadrature branch signal of GPS
iFor :-1 ,-1 ,-1 ,-1 ,-1,1 ,-1 ,-1,1,1 ,-1,1 ,-1,1 ,-1 ,-1,1,1,1 ,-1, the cycle is 20 milliseconds; N for the C/A sign indicating number of GLONASS
iFor: 1,1,1,1,1,1,1,1,1,1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1, the cycle is 20 milliseconds;
2) memory module storage data volume is 19+20*M, M＞0, the carrier-to-noise ratio decision that the value of M is estimated by acquisition phase.Acquisition phase is divided into four sections with signal intensity, and segmentation limit and corresponding M value are: as (a) 25dB/Hz＜C/N
0During＜=30dB/Hz, M=80 is as (b) 30dB/Hz＜C/N
0During＜=35dB/Hz, M=60 is as (c) 35dB/Hz＜C/N
0During＜=40dB/Hz, M=40 is as (d) 40dB/Hz＜C/N
0The time, M=20;
3) when memory module storage data volume reaches requirement, send the secondary capturing enabling signal to control module.
After the correlator output data is followed the tracks of in the memory module storage, control module control store module, frequency-variable module, matched filtering module and quadrature detector block will be caught the remaining Doppler frequency deviation scope in back and be divided into a plurality of frequencies; Frequency is searched for, is found target frequency and modulation telegraph text data upturned position/secondary coding reference position step to comprise:
1) catch back residue Doppler frequency deviation scope for-(1/4T) Hz～+ (1/4T) Hz; T is the acquisition phase coherent integration time, is 1 millisecond, and residue Doppler frequency deviation scope is cut apart; Be spaced apart 1/ (2Td) Hz; Wherein Td is 20 milliseconds for the modulation telegraph text data duration, and N=Td/T+1 frequency arranged.For example when having caught the residue Doppler frequency deviation for-250Hz～250Hz, having 21 frequencies needs search; When inherent spurious frequency deviation be-during 100Hz～100Hz, having 9 frequencies needs search.
2) for each frequency, the local carrier module in the control module control of conversion module produces local carrier; Control module reads follows the tracks of the correlator output data in the memory module, carry out frequency conversion with the local carrier conjugate multiplication;
3) data after the frequency conversion are through the matched filtering module, and matched filter progression is 20, and tap coefficient is respectively: for the C/A coded signal of GPS be: 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, like 301 among Fig. 3; For the quadrature branch signal of the L5 wave band of GPS be :-1 ,-1 ,-1 ,-1 ,-1,1 ,-1 ,-1,1,1 ,-1,1 ,-1,1 ,-1 ,-1,1,1,1 ,-1, like 302 among Fig. 3; For the C/A sign indicating number of GLONASS be: 1,1,1,1,1,1,1,1,1,1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1, like 303 among Fig. 3;
4) for each frequency, total 19+20*M the input data of matched filtering module, there is 20*M output data M＞0.Total M group data, every group of 20 data, numbering is respectively 0～19, corresponding possible modulation telegraph text data upturned position/secondary coding reference position of data of identical numbering in every group.Matched filtering module output data expression formula is z
M, δ, n, wherein m representes group number, scope is 0～M-1; δ is possible modulation telegraph text data upturned position/secondary coding reference position, and scope is 0～19, representes the frequency point number of current search with 0～No. 19 corresponding n of data in every group of data, and scope is 0～N-1;
5) for each frequency, to the M group data delivery of matched filtering module output, the 0th group of No. 0 data, the 1st group of No. 0 data are up to No. 0 data addition of M-1 group behind the delivery; The 0th group of No. 1 data, the 1st group of No. 1 data are up to No. 1 data addition of M-1 group; And the like, the 0th group of No. 19 data, the 1st group of No. 19 data are up to No. 19 data additions of M-1 group; Common property is given birth to 20 non-coherent integration data.Date expression after the accumulation is:
6) N total 20*N non-coherent integration data of frequency, non-coherent integration data H
δ, nDeliver to peak detection block; Peak detection block finds peak value, and the peak value frequency points corresponding is exactly the target frequency, is designated as
The numbering that peak value is corresponding is exactly to modulate telegraph text data upturned position/secondary coding reference position, is designated as
For each frequency, total 19+20*M the input data of matched filtering module, there is 20*M output data M＞0.Per 20 output datas are divided into 1 group, and total M group data step comprises:
Preceding 19 data of 1) matched filtering module input data are filled up preceding 19 of matched filtering module shift register, and since the 20th input data, data of every input are just exported data, total 20*M output data, M＞0;
2) matched filtering module output data the 0th～19 is divided into the 0th group, and the 20th～39 is divided into the 1st group, and the like the 20*M-20～20*M-1 be divided into M-1 group.
According to the target frequency, the tracking correlator output data of storage is carried out the frequency deviation correction; Reference position according to modulation telegraph text data upturned position/secondary coding; To carrying out coherent integration through the revised data of overdeviation; Coherent integration is carried out in same modulation telegraph text data, and the coherent integration time can the modulated telegraph text data duration be divided exactly step and comprised:
1) according to the target frequency
control module controls the inverter module generation module generates local carrier frequency
corresponds to the complex frequency carrier signal.Control module reads the data in the memory module, with local complex carrier signal signal conjugate multiplication, accomplishes the frequency deviation correction;
2) begin to carry out from the individual data of frequency deviation revised
according to modulation telegraph text data upturned position/secondary coding reference position
coherent integration, the coherent integration time is 1 millisecond, 2 milliseconds, 4 milliseconds, 5 milliseconds or 10 milliseconds.When signal intensity is in scope a, carry out 5 milliseconds of coherent integrations; When signal intensity is in scope b, carry out 4 milliseconds of coherent integrations;
When signal intensity is in scope c, carry out 2 milliseconds of coherent integrations; When signal intensity is in scope d, carry out 1 millisecond of coherent integration.
Data after the coherent integration are carried out square operation, eliminate the influence of modulation text data polarity; Data behind the square operation obtain meticulousr frequency deviation with spectrum analysis, and spectrum analysis is carried out step and comprised in the Frequency Estimation module:
1) square operation is eliminated the variation of modulation text positive-negative polarity, and inherent spurious frequency deviation also becomes original twice simultaneously;
2) the inherent spurious frequency deviation scope is-1/ (4Td) Hz～1/ (4Td) Hz behind the compensate of frequency deviation, square frequency deviation region is doubled, and becomes-1/ (2Td) Hz～1/ (2Td) Hz; Td is 20 milliseconds, and frequency deviation region is-25Hz～25Hz behind the compensate of frequency deviation; Spectral Analysis Method is estimated remaining Doppler frequency deviation behind the compensate of frequency deviation, can carry out the fine estimation of frequency deviation with 256 FFT.
As shown in Figure 1, the device of secondary capturing weak satellite navigation signals comprises like lower module: follow the tracks of correlator, memory module, frequency-variable module, matched filtering module, non-coherent integration module, peak detection block, coherent integration module, square module, Frequency Estimation module and control module; Following the tracks of correlator, memory module, frequency-variable module links to each other successively; Frequency-variable module links to each other with matched filtering module, coherent integration module respectively; Matched filtering module, non-coherent integration module, peak detection block link to each other successively; Coherent integration module, square module, Frequency Estimation module link to each other successively; Control module control is followed the tracks of the correlator output data and is stored memory module into, and memory module is sent the secondary capturing enabling signal to control module; Control module control store module output data, data find target frequency and modulation telegraph text data upturned position/secondary coding reference position through matched filtering module, non-coherent integration module, peak detection block; After finding the target frequency and modulating telegraph text data upturned position/secondary coding reference position; Control module control store module output data; Data are carried out the frequency deviation correction through frequency-variable module; Revised data are through coherent integration module, square module, and square module output data is carried out the fine estimation of frequency deviation through the Frequency Estimation module.
As shown in Figure 2, frequency-variable module comprises conjugate multiplication module, the local carrier module that is connected.
Embodiment
Initial acquisition accomplished pseudo-code phase and Doppler frequency deviation thicker synchronously, in our embodiment, acquisition phase carries out 1 millisecond coherent integration, pseudo-code is spaced apart 0.5 chip.Caught, residue chip phase deviation in-/+0.25 chip, the residue Doppler spread is-/+250Hz.Acquisition phase is accomplished the initial synchronisation of signal, has also obtained the guestimate of signal intensity, confirms the signal carrier-to-noise ratio is below in which scope;
a)25dB/Hz＜C/N
0＜＝30dB/Hz；
b)30dB/Hz＜C/N
0＜＝35dB/Hz；
c)35dB/Hz＜C/N
0＜＝40dB/Hz；
d)40dB/Hz＜C/N
0。
When the signal carrier-to-noise ratio was in scope a, it was the individual tracking correlator of 1619 (M=80) output data, the i.e. data of 1.619s that secondary capturing uses data volume; When the signal carrier-to-noise ratio was in scope b, it was the individual tracking correlator of 1219 (M=60) output data, the i.e. data of 1.219s that secondary capturing uses data volume; When the signal carrier-to-noise ratio was in scope c, it was the individual tracking correlator of 819 (M=40) output data, the i.e. data of 0.819s that secondary capturing uses data volume; When the signal carrier-to-noise ratio was in scope d, it was the individual tracking correlator of 419 (M=20) output data, the i.e. data of 0.419s that secondary capturing uses data volume.The secondary capturing of unlike signal carrier-to-noise ratio scope uses data volume to obtain according to emulation, through the actual measurement checking.
During actual measurement, the signal carrier-to-noise ratio is 27dB/Hz, and Doppler frequency deviation is 1156Hz, and signal format is the C/A sign indicating number of GPS, and the modulation telegraph text data upturned position of the tracking correlator output data of storage is the 3rd data.After catching completion, the chip phase near-synchronous, the residue Doppler frequency deviation is 156Hz, and the scope that estimates signal intensity place is a.The search frequency is-250Hz, 225Hz, 200Hz......220Hz, 225Hz, 250Hz during secondary capturing; Have 21 frequencies; The non-coherent integration module has 21 groups of output datas; Every group of corresponding frequency, every group of data have 20 data, the corresponding a kind of possible modulation telegraph text data upturned position/secondary coding reference position of each data.It is the 3rd data of the 17th group of data that peak detection block finds the position of peak value, shows that the target frequency is 150Hz, and modulation telegraph text data upturned position/secondary coding reference position is the 3rd data of input data.Control module is according to target frequency 150Hz, and control local carrier module produces the complex carrier signal signal of 150Hz, and the tracking correlator output data and the complex carrier signal signal conjugate multiplication that read in the memory module realize compensate of frequency deviation.The inherent spurious frequency deviation of data is 6Hz behind the compensate of frequency deviation.According to modulation telegraph text data upturned position/secondary coding reference position, since the 3rd data, per 5 data are carried out coherent integration, and the data after the coherent integration are carried out square operation.The equivalent sampling rate of the data behind the square operation is 200Hz, and inherent spurious frequency deviation is 12Hz, and these data are carried out 256 FFT computing, and the peak that finds FFT result is 16.The accurate estimated value of inherent spurious frequency deviation is 5.86Hz behind the compensate of frequency deviation according to calculating.
Claims (7)
1. the method for a secondary capturing weak satellite navigation signals is characterized in that comprising the steps:
1) under the control of control module, stores one group and follow the tracks of the correlator output data, the corresponding memory module of each tracing channel to memory module;
2) after the correlator output data is followed the tracks of in the memory module storage, control module control store module, frequency-variable module, matched filtering module and quadrature detector block will be caught the remaining Doppler frequency deviation scope in back and be divided into a plurality of frequencies; Frequency is searched for, found the target frequency and as the modulation telegraph text data upturned position of secondary coding reference position;
3), the tracking correlator output data of storage is carried out the frequency deviation correction according to the target frequency; According to the modulation telegraph text data upturned position as the secondary coding reference position, to carrying out coherent integration through the revised data of overdeviation, coherent integration is carried out in same modulation telegraph text data, and the coherent integration time can divide exactly the modulated telegraph text data duration;
4) data after the coherent integration are carried out square operation, eliminate the influence of modulation text data polarity; Data behind the square operation obtain meticulousr frequency deviation with spectrum analysis, and spectrum analysis is carried out in the Frequency Estimation module;
After the correlator output data is followed the tracks of in described memory module storage, control module control store module, frequency-variable module, matched filtering module and quadrature detector block will be caught the remaining Doppler frequency deviation scope in back and be divided into a plurality of frequencies; Frequency is searched for, is found the target frequency and comprise as the modulation telegraph text data upturned position step of secondary coding reference position:
1) catch back residue Doppler frequency deviation scope for-(1/4T) Hz～+ (1/4T) Hz; T is the acquisition phase coherent integration time, is 1 millisecond, and residue Doppler frequency deviation scope is cut apart; Be spaced apart 1/ (2Td) Hz; Wherein Td is 20 milliseconds for the modulation telegraph text data duration, and N=Td/T+1 frequency arranged;
2) for each frequency, the local complex carrier signal signaling module in the control module control of conversion module produces local complex carrier signal signal; Control module reads follows the tracks of the correlator output data in the memory module, carry out frequency conversion with local complex carrier signal signal conjugate multiplication;
3) data after the frequency conversion are through the matched filtering module, and matched filter progression is 20, and tap coefficient is respectively: for the C/A coded signal of GPS be: 1,1,1,1,1,1,1,1,1,1,1; 1,1,1,1,1,1,1,1,1, for the quadrature branch signal of the L5 wave band of GPS be :-1 ,-1 ,-1 ,-1;-1,1 ,-1 ,-1,1,1 ,-1,1 ,-1,1 ,-1 ,-1; 1,1,1 ,-1, for the C/A sign indicating number of GLONASS be: 1,1,1,1,1,1,1,1; 1,1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1 ,-1;
4) for each frequency, total 19+20*M the input data of matched filtering module, there is 20*M output data M＞0; Per 20 output datas are divided into 1 group, total M group data;
5) for each frequency, to the M group data delivery of matched filtering module output, the 0th group of No. 0 data, the 1st group of No. 0 data are up to No. 0 data addition of M-1 group behind the delivery; The 0th group of No. 1 data, the 1st group of No. 1 data are up to No. 1 data addition of M-1 group; And the like, the 0th group of No. 19 data, the 1st group of No. 19 data are up to No. 19 data additions of M-1 group; Common property is given birth to 20 non-coherent integration data;
6) N total 20*N non-coherent integration data of frequency, the non-coherent integration data are delivered to peak detection block; Peak detection block finds peak value; The peak value frequency points corresponding is exactly the target frequency; Being designated as the corresponding numbering of
peak value is exactly the modulation telegraph text data upturned position as the secondary coding reference position, is designated as
2. the method for a kind of secondary capturing weak satellite navigation signals according to claim 1; It is characterized in that; Described under the control of control module, store one group of output data of following the tracks of correlator to memory module, the corresponding memory module step of each tracing channel comprises:
1) following the tracks of the correlator output data is complex signal, and the SI is 1 millisecond, and promptly sampling rate is 1KHz, and each modulation telegraph text data has 20 sampled points;
2) memory module storage data volume is 19+20*M, M＞0, the carrier-to-noise ratio decision that the value of M is estimated by acquisition phase;
3) when memory module storage data volume reaches requirement, send the secondary capturing enabling signal to control module.
3. the method for a kind of secondary capturing weak satellite navigation signals according to claim 1 is characterized in that, and is described for each frequency, total 19+20*M the input data of matched filtering module, and there is 20*M output data M＞0; Per 20 output datas are divided into 1 group, and total M group data step comprises:
Preceding 19 data of 1) matched filtering module input data are filled up preceding 19 of matched filtering module shift register, and since the 20th input data, data of every input are just exported data, total 20*M output data, M＞0;
2) matched filtering module output data the 0th～19 is divided into the 0th group, and the 20th～39 is divided into the 1st group, and the like the 20*M-20～20*M-1 be divided into M-1 group.
4. the method for a kind of secondary capturing weak satellite navigation signals according to claim 1 is characterized in that, and is described according to the target frequency, and the tracking correlator output data of storage is carried out the frequency deviation correction; According to modulation telegraph text data upturned position as the secondary coding reference position; To carrying out coherent integration through the revised data of overdeviation; Coherent integration is carried out in same modulation telegraph text data, and the coherent integration time can the modulated telegraph text data duration be divided exactly step and comprised:
1) according to the target frequency
control module controls the conversion module of the local carrier wave signal generation module generates a complex frequency
corresponding frequencies of local complex carrier signal; control module reads the data storage module, local complex conjugate of a carrier signal, frequency offset correction completed;
2) begin to carry out from the individual data of frequency deviation revised
according to modulation telegraph text data upturned position
coherent integration as the secondary coding reference position, the coherent integration time is 1 millisecond, 2 milliseconds, 4 milliseconds, 5 milliseconds or 10 milliseconds.
5. the method for a kind of secondary capturing weak satellite navigation signals according to claim 1 is characterized in that, the data after the described coherent integration are carried out square operation, eliminates the influence of modulation text data polarity; Data behind the square operation obtain meticulousr frequency deviation with spectrum analysis, and spectrum analysis is carried out step and comprised in the Frequency Estimation module:
1) square operation is eliminated the variation of modulation text positive-negative polarity, and inherent spurious frequency deviation also becomes original twice simultaneously;
2) the inherent spurious frequency deviation scope is-1/ (4Td) Hz～1/ (4Td) Hz behind the compensate of frequency deviation, square frequency deviation region is doubled, and becomes-1/ (2Td) Hz～1/ (2Td) Hz; Td is 20 milliseconds, and frequency deviation region is-25Hz～25Hz behind the compensate of frequency deviation; Remaining Doppler frequency deviation behind the Spectral Analysis Method estimation compensate of frequency deviation.
6. device of the secondary capturing weak satellite navigation signals of method design according to claim 1; It is characterized in that, comprise: follow the tracks of correlator, memory module, frequency-variable module, matched filtering module, non-coherent integration module, peak detection block, coherent integration module, square module, Frequency Estimation module and control module like lower module; Following the tracks of correlator, memory module, frequency-variable module links to each other successively; Frequency-variable module links to each other with matched filtering module, coherent integration module respectively; Matched filtering module, non-coherent integration module, peak detection block link to each other successively; Coherent integration module, square module, Frequency Estimation module link to each other successively; Control module control is followed the tracks of the correlator output data and is stored memory module into, and memory module is sent the secondary capturing enabling signal to control module; Control module control store module output data, data find the target frequency through matched filtering module, non-coherent integration module, peak detection block and as the modulation telegraph text data upturned position of secondary coding reference position; After finding target frequency and modulation telegraph text data upturned position as the secondary coding reference position; Control module control store module output data; Data are carried out the frequency deviation correction through frequency-variable module; Revised data are through coherent integration module, square module, and square module output data is carried out the fine estimation of frequency deviation through the Frequency Estimation module.
7. the device of a kind of secondary capturing weak satellite navigation signals as claimed in claim 6 is characterized in that, described frequency-variable module comprises the conjugate multiplication module that is connected, local complex carrier signal signaling module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101529435A CN101666869B (en) | 2009-09-21 | 2009-09-21 | Method and device for secondary capturing weak satellite navigation signals |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101529435A CN101666869B (en) | 2009-09-21 | 2009-09-21 | Method and device for secondary capturing weak satellite navigation signals |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101666869A CN101666869A (en) | 2010-03-10 |
| CN101666869B true CN101666869B (en) | 2012-02-01 |
Family
ID=41803571
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2009101529435A Active CN101666869B (en) | 2009-09-21 | 2009-09-21 | Method and device for secondary capturing weak satellite navigation signals |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101666869B (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| MD4154C1 (en) * | 2010-03-16 | 2012-10-31 | Еуджен МОРАРУ | Unhooked parachute localization system |
| JP2012078348A (en) * | 2010-09-06 | 2012-04-19 | Seiko Epson Corp | Bit variation determination method and bit variation determination device |
| CN102565822B (en) * | 2011-10-09 | 2014-01-08 | 中国科学院计算技术研究所 | Capture method of GPS L5 signal and apparatus thereof |
| CN102608626B (en) * | 2012-03-09 | 2013-11-06 | 暨南大学 | High-sensitivity satellite navigation signal capturing method and system |
| CN103353599B (en) * | 2012-06-06 | 2015-10-28 | 泰斗微电子科技有限公司 | The method of a kind of Beidou navigation satellite-signal process, chip and module |
| FR2999298B1 (en) * | 2012-12-10 | 2015-01-09 | Sagem Defense Securite | METHOD AND DEVICE FOR DETERMINING THE TIME OF PROPAGATION OF A SURFACE ACOUSTIC WAVE FILTER |
| CN105527631B (en) * | 2014-11-26 | 2016-09-21 | 航天恒星科技有限公司 | Weak signal processing method based on GNSS receiver |
| CN104536020B (en) * | 2015-01-05 | 2017-10-31 | 泰斗微电子科技有限公司 | A kind of GNSS signal catching method |
| CN106896382B (en) * | 2015-12-18 | 2019-06-28 | 大唐半导体设计有限公司 | A kind of navigation signal catching method and device |
| CN108051829B (en) * | 2017-11-06 | 2021-09-28 | 深圳开阳电子股份有限公司 | Satellite navigation receiver and navigation bit synchronization method and device thereof |
| CN109655847B (en) * | 2018-11-27 | 2022-10-18 | 上海无线电设备研究所 | Fast capturing method suitable for dynamic signal |
| CN109660279A (en) * | 2018-12-20 | 2019-04-19 | 南京理工大学 | Missile-borne communication system based on spread spectrum communication system |
| CN110943758A (en) * | 2019-11-12 | 2020-03-31 | 天津津航计算技术研究所 | Secondary capturing method based on Doppler frequency change frequency and frequency joint search |
| CN111796305B (en) * | 2020-07-31 | 2023-05-02 | 北京中捷时代航空科技有限公司 | High dynamic navigation satellite signal receiving method and receiver |
| CN112684479B (en) * | 2020-11-23 | 2023-06-16 | 中国人民解放军国防科技大学 | Secondary capturing method of navigation receiver and navigation receiver thereof |
| CN113009524B (en) * | 2021-02-22 | 2023-09-29 | 浙江理工大学 | Navigation message bit flip estimation method and system for long-time coherent integration capture |
| CN115291258B (en) * | 2022-10-08 | 2022-12-13 | 成都星航时空科技有限公司 | GNSS baseband capturing method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6201497B1 (en) * | 1997-09-30 | 2001-03-13 | Dlb Limited | Enhanced global navigation satellite system |
| CN101110602A (en) * | 2006-07-20 | 2008-01-23 | 上海高清数字科技产业有限公司 | Carrier wave catching system and method based on multimode operation |
| CN101312447A (en) * | 2008-05-23 | 2008-11-26 | 北京创毅视讯科技有限公司 | Integral frequency bias and fine synchronization method and apparatus of receiver |
-
2009
- 2009-09-21 CN CN2009101529435A patent/CN101666869B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6201497B1 (en) * | 1997-09-30 | 2001-03-13 | Dlb Limited | Enhanced global navigation satellite system |
| CN101110602A (en) * | 2006-07-20 | 2008-01-23 | 上海高清数字科技产业有限公司 | Carrier wave catching system and method based on multimode operation |
| CN101312447A (en) * | 2008-05-23 | 2008-11-26 | 北京创毅视讯科技有限公司 | Integral frequency bias and fine synchronization method and apparatus of receiver |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101666869A (en) | 2010-03-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101666869B (en) | Method and device for secondary capturing weak satellite navigation signals | |
| EP1829232B1 (en) | Determination of a code phase | |
| CN104407323B (en) | A kind of high dynamic low signal-to-noise ratio spread-spectrum signal pseudo-code time-delay measuring method | |
| CN102016621B (en) | Apparatus and method for cross-correlation spur mitigation | |
| US7920093B2 (en) | Methods for improving computational efficiency in a global positioning satellite receiver | |
| MXPA05000474A (en) | Cross-correlation mitigation method and apparatus for use in a global positioning system receiver. | |
| CN102608626A (en) | High-sensitivity satellite navigation signal capturing method and system | |
| CN102594393A (en) | Universal pseudocode synchronization system of comprehensive satellite baseband equipment | |
| CN101464507B (en) | Baseband signal processing method and system for Galilei system | |
| US20060114984A1 (en) | Method and apparatus for increasing coherent integration length while receiving a positioning signal | |
| KR20150086760A (en) | Signal processing method for ultra-fast acquisition and tracking of severely attenuated spread spectrum signals with doppler frequency and apparatus thereof | |
| JPH11183586A (en) | Receiver for complete high-frequency navigation especially based on gps | |
| CN104765052B (en) | GEO navigation satellite high-sensitivity carrier tracking method | |
| CN103176189A (en) | Near-far effect suppressor for high-flexibility satellite navigation receiver and near-far effect suppressing method thereof | |
| CN104570017A (en) | Avoiding and stripping method for Neumann-Hoffman codes in navigation messages of Beidou navigation satellite system D1 | |
| CN116745647A (en) | Modern consumer-level GNSS secondary code acquisition and signal tracking | |
| WO2019020201A1 (en) | A receiver and method for processing a wide-band signal | |
| US6810072B1 (en) | System for acquiring spread spectrum signals | |
| CN102841359B (en) | Two-dimensional capturing method for carrier pseudo codes of direct sequence spread spectrum signals capable of preventing turnover of messages | |
| US20110050496A1 (en) | Energy Domain Based Peak Reconstruction Methods And Apparatuses | |
| CN105527632A (en) | Weak signal processing method and device of global satellite navigation system | |
| US7876738B2 (en) | Preventing an incorrect synchronization between a received code-modulated signal and a replica code | |
| EP1260030B1 (en) | A receiver for a spread spectrum system | |
| US7308021B2 (en) | Method in the synchronization of a receiver, and a receiver | |
| CN104422939B (en) | Method and apparatus for being associated with the signal received from navigational satellite system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C53 | Correction of patent for invention or patent application | ||
| CB03 | Change of inventor or designer information |
Inventor after: Wang Yongsong Inventor after: Zhao Minjian Inventor after: Zhong Jie Inventor after: Hou Weiwei Inventor after: Li Yunfei Inventor after: Wang Yue Inventor before: Wang Yongsong Inventor before: Zhao Minjian Inventor before: Hou Weiwei Inventor before: Li Yunfei Inventor before: Wang Yue |
|
| COR | Change of bibliographic data |
Free format text: CORRECT: INVENTOR; FROM: WANG YONGSONG ZHAO MINJIAN HOU WEIWEI LI YUNFEI WANG YUE TO: WANG YONGSONGZHAO MINJIAN ZHONG JIE HOU WEIWEI LI YUNFEI WANG YUE |
|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |