CN102608626B - High-sensitivity satellite navigation signal capturing method and system - Google Patents
High-sensitivity satellite navigation signal capturing method and system Download PDFInfo
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Abstract
The invention discloses a high-sensitivity satellite navigation signal capturing method and a system. The system comprises a digital down-conversion module, an average sampling and block accumulation module, an FFT (fast Fourier transform) module, a circumference shifting module, a local PRN (pseudo random noise) code FFT conjugate memory, a complex multiplier module, an IFFT (inverse fast Fourier transform) module, a differential coherence integration module, a peak detection module and a sequential control module. The digital down-conversion module realizes digital down-conversion operation for satellite digital intermediate frequency signals; the average sampling and block accumulation module averagely samples satellite data and completes a block accumulation function; the FFT module searches code phase frequency domains; the circumference shifting module utilizes Doppler circumference shifting search to replace frequency compensation; the local PRN code FFT conjugate memory stores a local PRN code FFT conjugate result; the complex multiplier module realizes signal de-spreading; the IFFT module calculates different code phase coherence results; the differential coherence integration module accumulates differential coherence energy of de-spread satellite signals; the peak detection module realizes signal capturing output; and the sequential control module controls timing sequence of the various modules of the system. Weak signal capturing speed and sensitivity of a satellite navigation receiver are improved, and parameters can be configured flexibly.
Description
Technical field
The present invention relates to satellite navigation signals and catch research field, particularly a kind of high sensitivity method for capturing satellite navigation signal and system.
Background technology
GPS (Global Positioning System, GPS) be 20 century 70s by the global navigation satellite system of U.S. land, sea, and air joint research and development on the basis of Navy, it is made of space segment, ground control section and user segment three parts.Gps system also obtains widespread use at civil area, has developed into the international new high-tech industry of multi-field, multi-mode, multi-usage, multi-model.GPS System in USA is satellite navigation and the positioning system of global widespread use.At present, can enter " Galileo " system in the Muscovite GLONASS of having respectively of competitive field system, Europe and the Big Dipper (COMPASS) system of China with gps system.
the course of work of satellite navigation receiver is: the radiofrequency signal of satellite launch (RF) is got off by antenna reception, by a passive band-pass filter, to reduce to be with outer Radio frequency interference (RFI), follow pre-amplification, radiofrequency signal is down-converted to intermediate frequency (IF), use again modulus (A/D) transducer to (IF) signal sampling and digitizing, obtain digital medium-frequency signal (or digital baseband signal), sending into digital baseband processor (Digital Base-band Processor) processes again, mainly that signal is caught, follow the tracks of, demodulation, remake navigation calculation, its computation of pseudoranges etc., digital baseband processor is the core of satellite signal receiver.
Wherein digital baseband signal is processed, at first to carry out catching of signal, its objective is and determine that a satellite is whether in the visible range of receiver, if satellite as seen, acquisition procedure will be completed catching of two parameters: code phase and carrier frequency, this is a two-dimensional search process in fact.Satellite signal acquisition is exactly to carry out two-dimensional search to obtain rough carrier frequency and the process of code phase on frequency and PRN code direction.Catching is key components in satellite signal receiver.
Method for acquiring pseudo code commonly used mainly contains transmitted reference signal method, Sequential correlation method, matched filter method, sliding correlation method etc. at present.The transmitted reference signal method is exactly having modulated the spread-spectrum signal of data and not had the data signal transmission of Data Modulation to go out, directly carry out despreading with these two parts at receiving end, the method is insensitive on the impact of Doppler shift, but the anti-interference of system and very poor to noise inhibiting ability.The Sequential correlation method is a kind of quick capturing method that can reduce the long code capture time, but it could inject shift register after first will detecting external PRN code, and this point is more difficult.Matched filter method advantage is real-time, can realize Fast synchronization.But the matched filter hardware under existing process conditions for long code fast acquisition is realized more difficult.
In various spread spectrum systems, sliding correlation method uses the most extensive.Because the method realizes simple, and without any need for prior imformation.Sliding correlation method mainly comprises time domain sliding correlation method and frequency domain sliding correlation method.The time domain sliding correlation method adopts reception signal and local signal to carry out multistage correlation integral in time domain, and through multistage correlation integral, signal intensity is increased dramatically, thereby obtains correlation peak.This algorithm is realized fairly simple, but acquisition procedure is consuming time longer.The Typical Representative of frequency domain sliding correlation method is that Vanne etc. proposes the PRN code capture method based on fast fourier transform (FFT).This algorithm utilizes twice FFT and an inverse Fourier transform (IFFT) computing to calculate the correlation peak that receives signal and reference signal, thereby determines Doppler frequency deviation and PRN code phase.The FFT computing that this algorithm will be counted is greatly especially counted when not being 2 power side, and operand is larger, and system hardware resources is had relatively high expectations.
The navigation signal reception technique nowadays application demand under the serious signal dropout environment such as indoor, built-up avenue and parking lot is more and more.Most user distributions of hand-held positioning equipment of using are in the intensive urban area of high building, need to be between indoor, high building, complete the location in the feeble signal environment such as underground parking, overpass, in the control of city suburbs and train location is used, owing to there being the barriers such as massif, building, trees, tunnel, satellite navigation signals is blocked, multipath effect etc. affects, signal is very faint, and decay is serious.These have brought challenge all for the satellite signal receiving technology.Common receiver is because the restriction of sensitivity can't be used under these conditions.For the normal satellite navigation signals that receives under weak signal conditions, receiver need to increase the cumulative time of signal energy, improves signal to noise ratio (S/N ratio).Improving the signal to noise ratio (S/N ratio) of correlator output, is the unique channel that realizes that feeble signal is synchronous.This means, not only need long-time integration and frequency deviation estimation more accurately, and need to increase the scale of hardware correlator.Existing many integration methods all can be unified the combination for coherent integration and two kinds of methods of non-coherent integration, and difference is the number of times of time span and the non-coherent integration of coherent integration.
The coherent integration time is longer, and coherent gain is larger, but coherent integration length neither be unlimited, and it can be subject to the restriction of Doppler shift, navigation data bit width and calculated amount etc.Another problem of long-time coherent integration is that integration accumulation process process may exist the problem of crossing over the navigation message data bit.If data bit generation saltus step in integral time will cause the counteracting of the data message of processing, the coherent integration value reduces on the contrary.Non-coherent integration is not subjected to the impact of symbol saltus step and carrier doppler, can carry out energy accumulation on a plurality of navigation message data bit.But the length of non-coherent integration is subjected to yard Doppler's restriction, and along with the noncoherent accumulation number of times increases, the DeGrain that energy increases.
Summary of the invention
Fundamental purpose of the present invention is to overcome the shortcoming of existing satellite signal receiving and treatment technology with not enough, a kind of high sensitivity method for capturing satellite navigation signal is provided, the method can realize the fast Acquisition of weak satellite signal under different scenes for " Big Dipper " of the GPS of the U.S. and China (COMPASS) two systems.
One object of the present invention realizes by following technical scheme: a kind of high sensitivity method for capturing satellite navigation signal comprises the following steps:
(1) according to current trapped state, the satellite digital intermediate-freuqncy signal of the request corresponding different time length of input and starting point;
(2) Digital Down Convert, average sample and FFT operation are carried out in the signal of input, obtain the satellite frequency-region signal of zero intermediate frequency, low sampling rate, also carried out in addition the piece stack when average sample;
(3) enter the frequency search state, carrying out frequency domain correlation, differential coherence integration and peak value for the 1st starting point partial data section of input detects, and by the different frequency compensations that realize based on the circular shifting search in the address of reading first data, detect and record peak-peak and the corresponding circular shifting n that counts, and adjust local carrier frequency for considering the frequency of Doppler shift;
(4) enter the starting point search condition, carrying out frequency domain correlation, differential coherence integration and peak value for other starting point partial data sections except the 1st starting point detects, detect and record the peak value that all starting point data groups obtain, the peak-peak correspondence optimized start point sequence number k;
(5) enter normal trapped state, input the total data section of k starting point and carry out frequency domain correlation, differential coherence integration and peak value detection, the peak value that obtains and detection threshold are relatively, if greater than detection threshold, acquisition success is described, output peak-peak and corresponding code phase and carrier frequency thereof; Otherwise catch unsuccessfully.
The present invention also provides a kind of capture systems based on above-mentioned high sensitivity method for capturing satellite navigation signal.This system comprises:
Digital Down Converter Module is used for the satellite intermediate frequency signal sample data of input is carried out the Digital Down Convert operation, obtains the satellite sampled data of zero intermediate frequency;
Average sample and piece accumulator module are connected with described Digital Down Converter Module, are used for the zero intermediate frequency satellite-signal after down coversion is averaged sampling and the cumulative operation of piece, obtain the zero intermediate frequency satellite-signal data of low sampling rate;
The FFT module is connected with described average sample and piece accumulator module, and satellite-signal is carried out Fast Fourier Transform (FFT), carries out the search of code phase spectrum correlation;
The circular shifting module is connected with described FFT module, and the FFT Output rusults of satellite-signal is carried out Doppler's circular shifting, realizes the search to Doppler shift;
The complex multiplier module is connected with described circular shifting module, for despreading that satellite-signal is multiplied each other;
Local PRN code FFT conjugation storer is connected with described complex multiplier module, for storing the result of getting conjugation after local PRN code FFT;
The IFFT module is connected with described complex multiplier module, is used for obtaining the correlated results of different code phases to taking advantage of again result to carry out reverse Fast Fourier Transform (FFT);
The differential coherence integration module is connected with described IFFT module, is used for the correlated results of different code phases is carried out the difference correlation energy accumulation;
Peak detection block is connected with described differential coherence integration module, is used for cumulative correlation energy peak value is detected, and realizes the output of satellite signal acquisition and Doppler shift and code phase;
Time-sequence control module, be connected with peak detection block with described Digital Down Converter Module, average sample and piece accumulator module, FFT module, circular shifting module, local PRN code FFT conjugation storer, complex multiplier module, IFFT module, differential coherence integration module, time-sequence control module is based on catches flow process and utilizes state machine to realize, in the control parameter of different State-output disparate modules, realize the workflow of whole system and the working state control of modules.
Described Digital Down Converter Module comprises: Direct Digital Frequency Synthesizers, be connected with the circular shifting module, and be used for producing the sine of certain frequency and cosine carrier signal as local carrier according to frequency control; Digital mixer is connected with described Direct Digital Frequency Synthesizers, is used for realizing the local intermediate frequency carrier that produces and the satellite intermediate frequency sampled data mixing of input.
Further, described digital mixer is according to in-phase component (In-phase component, the I branch road) and quadrature component (Quadrature component, the Q branch road) be divided into I frequency mixer and Q frequency mixer, I frequency mixer and Q frequency mixer respectively with the satellite intermediate frequency sampled data mixing of outside input.
Described average sample and piece accumulator module comprise:
Data accumulator is connected with described digital mixer, is used for adding up to the input data;
2
NAddress generator is connected with described data accumulator, produces 2
NIndividual address is for the sampled data storer;
The sampled data storer is with described data accumulator, 2
NAddress generator is connected with the FFT module, is used for the satellite data after storage average sample and piece add up;
Data output switch, be connected with the sampled data storer with described data accumulator, be used for when carrying out the cumulative operation of piece, control the cumulative data of upper one-period that the sampled data storer is read and output in data accumulator with current zero intermediate frequency signals data and add up.
Described circular shifting module comprises:
FFT real part storer is connected with described FFT module, is used for the real part data of storage FFT output;
FFT imaginary part storer is connected with described FFT module, is used for the imaginary data of storage FFT output;
The circular shifting address generator is connected with FFT imaginary part storer with described FFT real part storer, is used for counting according to displacement producing 2 of different starting points
NIndividual address.
Described differential coherence integration module comprises:
The differential coherence processing module is connected with described IFFT module, is used for relevant result is carried out the differential coherence operation;
Relevant real part storer, be connected with described differential coherence processing module, the real part data that are used for the relevant result of storage, these storage data are carried out with the relevant real part of next cycle in next differential coherence integration period is read out to the differential coherence processing module and are multiplied each other;
Relevant imaginary part storer as a result, be connected with described differential coherence processing module, the imaginary data that is used for the relevant result of storage, these storage data are carried out with the relevant imaginary part as a result of next cycle in next differential coherence integration period is read out to the differential coherence processing module and are multiplied each other;
The differential coherence result memory, be connected with peak detection block with described differential coherence processing module, be used for storage and send the differential coherence result data, the storage data are carried out cumulative with the differential coherence result of next cycle in next differential coherence integration period is read out to the differential coherence processing module.
The present invention compared with prior art has following advantage and beneficial effect:
1, the present invention can realize the fast Acquisition of weak satellite signal under different scenes, has the advantages that operation time is short, acquisition speed is fast.In the present invention, piece accumulative frequency, differential coherence integral number of times and acquisition threshold can arrange flexibly according to scene or the Signal-to-Noise that detects, and improve acquisition speed and sensitivity, have embodied the configuration flexibility of technical solution of the present invention.Strong or for acquisition sensitivity in less demanding situation at signal, the correlated results of the different code phases that can be directly IFFT be obtained is directly inputted to peak detection block, directly judge corresponding code phase information and frequency information, this processing has improved catches treatment effeciency.
2, the trapped state in the present invention comprises frequency search state, starting point search condition and normal trapped state.Wherein, what the frequency search state read in is the 1st starting point data group of short period length, and purpose is to search for by circular shifting to obtain Doppler shift.Than determining Doppler shift with the partial data section, the method has reduced calculated amount.What the starting point search condition read in is other starting point data groups except the 1st starting point data group of short period length, and purpose is to select most suitable starting point, makes the point after average sample can embody well real signal.Than determining most suitable starting point with the partial data section, the method has reduced calculated amount.What normal trapped state was read in is the k starting point data group of complete length, and after the frequency search state, local carrier frequency has been adjusted into the intermediate frequency carrier frequency after the consideration Doppler shift.The data of reading in complete length this moment are caught, and are conducive to improve the signal to noise ratio (S/N ratio) of lock-on signal.
3, in the present invention, combine the thought of piece stack in the average sample stage, the data of the L millisecond (ms) of input being grown (L＜20) are divided into the data block of L 1ms and superpose according to constant time range is corresponding, carry out frequency domain correlation by the FFT module again, can make like this FFT/IFFT calculated amount reduce L number of times doubly, improve operation efficiency.
4, in the present invention, the target of frequency and starting point search is in order to seek Doppler shift and suitable data starting point, when detecting, peak value only needs to seek that peak-peak and circular shifting corresponding to output are counted and the sequence number of starting point data group gets final product, do not exist thresholding that problem is set, simplified operation.
Description of drawings
Fig. 1 is the basic composition block diagram of system of the present invention;
Fig. 2 is the composition schematic diagram of Digital Down Converter Module in system of the present invention;
Fig. 3 is the composition schematic diagram of average sample and piece accumulator module in system of the present invention;
Fig. 4 is the composition schematic diagram of circular shifting module in system of the present invention;
Fig. 5 is the composition schematic diagram of differential coherence integration module in system of the present invention;
Fig. 6 is the schematic flow sheet of the inventive method;
Fig. 7 is the treatment scheme schematic diagram of signal acquisition system when practical application in the embodiment of the present invention.
Embodiment
The present invention is described in further detail below in conjunction with embodiment and accompanying drawing, but embodiments of the present invention are not limited to this.
Embodiment 1
As shown in Figure 1, a kind of high sensitivity satellite navigation signals capture systems, mainly comprise time-sequence control module, Digital Down Converter Module, average sample and piece accumulator module, FFT module, circular shifting module, local PRN code FFT conjugation storer, IFFT module, complex multiplier module, differential coherence integration module and peak detection block, wherein:
Digital Down Converter Module is used for the satellite intermediate frequency signal sample data of input is carried out the Digital Down Convert operation, obtains the satellite sampled data of zero intermediate frequency, and these data are input in average sample and piece accumulator module and process;
Average sample and piece accumulator module are connected with described Digital Down Converter Module, are used for the zero intermediate frequency satellite-signal after down coversion is averaged sampling and the cumulative operation of piece, obtain the zero intermediate frequency satellite-signal data of low sampling rate;
The FFT module is connected with average sample and piece accumulator module, is used for satellite-signal is carried out Fast Fourier Transform (FFT), is used for satellite-signal is carried out the search of code phase spectrum correlation, has greatly improved the speed of search than traditional time domain serial search mode;
The circular shifting module is connected with the FFT module, and the FFT Output rusults of satellite-signal is carried out Doppler's circular shifting, realizes the search to Doppler shift;
The complex multiplier module is connected with the circular shifting module, for despreading that satellite-signal is multiplied each other;
Local PRN code FFT conjugation storer is connected with described complex multiplier module, for storing the result of getting conjugation after local PRN code FFT;
The IFFT module is connected with the complex multiplier module, is used for obtaining the correlated results of different code phases to taking advantage of again result to carry out reverse fast Fourier computing;
The differential coherence integration module is connected with the IFFT module, is used for the correlated results of different code phases is carried out the difference correlation energy accumulation;
Peak detection block is connected with the differential coherence integration module, is used for cumulative correlation energy peak value is detected, and realizes the output of satellite signal acquisition and Doppler shift and code phase;
Time-sequence control module, be connected with peak detection block with Digital Down Converter Module, average sample and piece accumulator module, FFT module, circular shifting module, local PRN code FFT conjugation storer, complex multiplier module, IFFT module, differential coherence integration module, utilize state machine to realize based on catching flow process, in the control parameter of different State-output disparate modules, realize the workflow of whole system and the working state control of modules.Wherein control parameter and comprise the modules enable signal, reset signal, address control signal, circular shifting parameter signal etc.
As shown in Figure 2, this Digital Down Converter Module mainly comprises Direct Digital Frequency Synthesizers and digital mixer, wherein:
Direct Digital Frequency Synthesizers, be connected with the circular shifting module, be used for producing the sine of certain frequency and cosine carrier signal as local carrier according to frequency control, the intermediate frequency carrier frequency of exporting in this enforcement sample is 4.092MHz, frequency resolution is 0.1Hz, and the output bit wide is 4bit; Certainly, also can adopt different IF-FRE in other embodiment;
Digital mixer is connected with Direct Digital Frequency Synthesizers, is used for realizing the local intermediate frequency carrier that produces and the mixing of input satellite intermediate frequency sampled data.Digital mixer is divided into I frequency mixer and Q frequency mixer according to in-phase component and quadrature component, I frequency mixer and Q frequency mixer respectively with the satellite intermediate frequency sampled data mixing of outside input.In this enforcement sample, the satellite digital intermediate-freuqncy signal of outside input is the 2bit sampling, can utilize the shirtsleeve operations such as addition and negate to realize with the mixing of local carrier signal, avoids using the extra hardware expense of multiplier;
As shown in Figure 3, this average sample and piece accumulator module mainly comprise data accumulator, 2
NAddress generator, sampled data storer and data output switch, wherein:
Data accumulator is connected with digital mixer, is used for realizing to inputting the cumulative of data the function that average sample and piece are cumulative; In this enforcement sample, sample frequency is 6.144MHz, and the accumulative frequency of the average sample of employing is 6 times, and the number of times of average sample can be determined by the external parameter input;
2
NAddress generator is connected with data accumulator, produces 2
NIndividual address is for the sampled data storer;
The sampled data storer is RAM in the present embodiment, with data accumulator, 2
NAddress generator is connected with the FFT module, is used for the satellite data after storage average sample and piece add up;
Data output switch, be connected with the sampled data storer with data accumulator, when carrying out the piece accumulation process, control the cumulative data of upper one-period that the sampled data storer is read and output in data accumulator with current zero intermediate frequency signals data and add up.
As shown in Figure 4, the circular shifting module mainly comprises FFT real part storer, FFT imaginary part storer and circular shifting address generator, wherein:
FFT real part storer is connected with the FFT module, is single port RAM in the present embodiment, and is set to the pattern of readfirst.This pattern is when writing new data to RAM, and the legacy data of data-out port output corresponding address has been saved the clock period, is used for the real part data of storage FFT output;
FFT imaginary part storer is connected with the FFT module, is single port RAM in the present embodiment, and is set to the pattern of readfirst.This pattern is when writing new data to RAM, and the legacy data of data-out port output corresponding address has been saved the clock period, is used for the imaginary data of storage FFT output;
The circular shifting address generator is connected with FFT imaginary part storer with FFT real part storer, is used for counting according to displacement producing 2 of different starting points
NIndividual address.This address is used for the data of read-write FFT real part storer and FFT imaginary part storer according to the circular shifting generation of counting.The read/write address generation rule is as follows: establish n and be counting of being shifted, n ∈ [10,10].As n〉0 the time, start address start_address=2
N-n+1, when n＜0, start address start_address=-n.The method has been saved hardware resource than general displacement method, utilizes simultaneously the search of Doppler's circular shifting to carry out frequency compensation, has reduced the operand of FFT.
As shown in Figure 5, the differential coherence integration module mainly comprises differential coherence processing module, relevant real part storer, relevant imaginary part storer and differential coherence result memory as a result, wherein:
The differential coherence processing module is connected with IFFT, is used for relevant result is carried out the differential coherence integration operation, and the differential coherence integral result that obtains is stored in the differential coherence result memory; The differential coherence number of processes can according to the power of satellite-signal, be controlled by the outside input flexibly;
Relevant real part storer, be connected with the differential coherence processing module, the real part data that are used for the relevant result of storage, these storage data are carried out with the relevant real part of next cycle in next differential coherence integration period is read out to the differential coherence processing module and are multiplied each other;
Relevant imaginary part storer as a result, be connected with the differential coherence processing module, the imaginary data that is used for the relevant result of storage, these storage data are carried out with the relevant imaginary part as a result of next cycle in next differential coherence integration period is read out to the differential coherence processing module and are multiplied each other;
The differential coherence result memory, be connected with the differential coherence processing module, be used for storage and send the differential coherence result data, the storage data are carried out cumulative with the differential coherence result of next cycle in next differential coherence integration period is read out to the differential coherence processing module.
Peak detection block is connected with described differential coherence integration module, is used for the energy peak of differential coherence integration is detected, and realizes the output of satellite signal acquisition and Doppler shift and code phase.The thresholding that peak value detects can be preset empirical value, and this module leaves external interface simultaneously, can and rational peak value detection threshold be set by the different scenes of microprocessor judges.
Data with local PRN code FFT conjugation storer after general satellite digital intermediate-freuqncy signal process FFT module multiply each other, obtain again the correlated results of different code phases after process IFFT module, more successively through being captured to Doppler shift and code phase after differential coherence integration module and peak detection block processing.The piece accumulative frequency, differential coherence integral number of times and acquisition threshold can arrange flexibly according to scene or the Signal-to-Noise that detects, and improve acquisition speed and sensitivity, have embodied the configuration flexibility of technical solution of the present invention.Strong or for acquisition sensitivity in less demanding situation at signal, the correlated results that can be directly IFFT be obtained different code phases is directly inputted to peak detection block, directly judge corresponding code phase information and frequency information, this processing has improved catches treatment effeciency.
Fig. 6 is satellite digital intermediate-freuqncy signal catching method schematic flow sheet of the present invention.In conjunction with the system embodiment of Fig. 1 to Fig. 5, embodiment of the method shown in Figure 6 mainly comprises following step:
Step 602 is carried out Digital Down Convert, average sample and FFT operation to the signal of inputting, and obtains the satellite frequency-region signal of zero intermediate frequency, low sampling rate;
Fig. 7 is the treatment scheme schematic diagram of signal acquisition system when practical application in the embodiment of the present invention.As shown in Figure 7, the actual treatment flow process of this signal acquisition system mainly comprises the steps:
Step 701 according to trapped state, reads the satellite digital intermediate-freuqncy signal of corresponding time span and starting point;
Step 702 is carried out Digital Down Convert, average sample and piece to the satellite digital intermediate-freuqncy signal and is added up, and obtains the digital medium-frequency signal of zero intermediate frequency and low sampling rate, then passes through the FFT conversion, obtains the frequency-region signal of this signal;
Step 703 judges whether to complete the search of frequency and starting point, is to turn step 713, otherwise turns step 704;
Step 704 utilizes Doppler's circular shifting to carry out the frequency compensation operation;
Step 705 is carried out complex multiplication and IFFT to frequency compensated result;
Step 706 is carried out differential coherence and peak value and is detected;
Step 710 is according to Doppler's circular shifting change local carrier frequency of counting;
Step 712 is carried out complex multiplication and IFFT to the complete length data group of k starting point;
Step 713 is carried out differential coherence integration and peak value detection to the complete length data group of k starting point;
Whether step 714 judges peak value greater than thresholding, is to turn step 715, otherwise turns step 717;
Step 717 is caught unsuccessfully, and putting the acquisition success zone bit is 0, EO.
Wherein, trapped state comprises frequency search state, starting point search condition and normal trapped state.
Wherein, what the frequency search state read in is the 1st starting point data group of short period length, and purpose is to search for by circular shifting to obtain Doppler shift.Than determining Doppler shift with the partial data section, the method has reduced calculated amount.
Wherein, what the starting point search condition read in is other starting point data groups except the 1st starting point data group of short period length, and purpose is to select most suitable starting point, makes the point after average sample can embody well real signal.Than determining most suitable starting point with the partial data section, the method has reduced calculated amount.In this enforcement sample, the partial data segment length is 100ms, and the data segment that frequency search and starting point search condition adopt is 10ms.
Wherein, what normal trapped state was read in is the k starting point data group of complete length, and after the frequency search state, local carrier frequency has been adjusted into the intermediate frequency carrier frequency after the consideration Doppler shift.The data of reading in complete length this moment are caught, and are conducive to improve the signal to noise ratio (S/N ratio) of lock-on signal.
Wherein, combine the thought of piece stack in the average sample stage, the data of the L millisecond (ms) of input being grown (L＜20) are divided into the data block of L 1ms and superpose according to constant time range is corresponding, carry out frequency domain correlation by the FFT module again, can make like this FFT/IFFT calculated amount reduce L number of times doubly, improve operation efficiency.
Wherein, Doppler's circle moves counts by time-sequence control module output, and in this enforcement sample, the hunting zone is determined can cover Doppler shift situation generally in the scope of [10KHz, 10KHz].
Wherein, the target of frequency and starting point search is in order to seek Doppler shift and suitable data starting point, only need when peak value detects to seek that peak-peak and circular shifting corresponding to output are counted and the sequence number of starting point data group gets final product, do not exist thresholding that problem is set, simplified operation.
Wherein, the thresholding that peak value detects can be preset empirical value, also can by external unit (as microprocessor) the different scenes of judgement and state of signal-to-noise, by external interface, rational peak value detection threshold be set.
Wherein, in this enforcement sample, the block count L of data block and differential coherence time number average has been preset initial value 10, can arrange flexibly according to the state of signal-to-noise of current acknowledge(ment) signal or to the sensitivity of catching and the requirement of speed in practical application.
Each module of foregoing invention or each step can be used on universal computing platform and realize.They can be used on universal computing platform and realize with executable program code, and perhaps make the integrated circuit IP kernel and realize, the present invention is not restricted to the combination of the software and hardware of any characteristics, has larger usability.
Although the disclosed embodiment of the present invention is as above, described content be the high sensitivity signal capture systems design of satellite navigation receiver and method in the embodiment of specific occasion, be not to limit the present invention.Under the prerequisite that does not break away from the disclosed spirit and scope of the present invention, can do certain modification on the concrete mode of implementing and details and change.
Above-described embodiment is the better embodiment of the present invention; but embodiments of the present invention are not restricted to the described embodiments; other any do not deviate from change, the modification done under Spirit Essence of the present invention and principle, substitutes, combination, simplify; all should be the substitute mode of equivalence, within being included in protection scope of the present invention.
Claims (7)
1. a high sensitivity method for capturing satellite navigation signal, is characterized in that, comprises the following steps:
(1) according to current trapped state, the satellite digital intermediate-freuqncy signal of the request corresponding different time length of input and starting point;
(2) signal of input carried out Digital Down Convert, average sample and FFT operation, obtain the satellite frequency-region signal of zero intermediate frequency, low sampling rate; Also carried out the piece stack during average sample, specifically: the long data of L millisecond of input are divided into the data block of L 1ms and superpose according to constant time range is corresponding;
(3) enter the frequency search state, carrying out frequency domain correlation, differential coherence integration and peak value for the 1st starting point partial data section of input detects, and carry out frequency compensation by circular shifting search, detect and record peak-peak and the corresponding circular shifting n that counts, and adjust local carrier frequency for considering the frequency of Doppler shift; Adopted the circular shifting search to carry out frequency compensation, realize the circular shifting search by the address difference that reads first data, the read/write address generation rule is as follows: n ∈ [10,10], as n〉0 the time, the start address start_address=2 of the data of read-write FFT real part storer and FFT imaginary part storer
N-n+1, when n＜0, start address start_address=-n;
(4) enter the starting point search condition, carrying out frequency domain correlation, differential coherence integration and peak value for other starting point partial data sections except the 1st starting point detects, detect and record the peak value that all starting point data groups obtain, the peak-peak correspondence optimized start point sequence number k;
(5) enter normal trapped state, input the total data section of k starting point and carry out frequency domain correlation, differential coherence integration and peak value detection, the peak value that obtains and detection threshold are relatively, if greater than detection threshold, acquisition success is described, output peak-peak and corresponding code phase and carrier frequency thereof; Otherwise catch unsuccessfully.
2. the capture systems based on the described high sensitivity method for capturing satellite navigation signal of claim 1, is characterized in that, comprising:
Digital Down Converter Module is used for the satellite intermediate frequency signal sample data of input is carried out the Digital Down Convert operation, obtains the satellite sampled data of zero intermediate frequency;
Average sample and piece accumulator module are connected with described Digital Down Converter Module, are used for the zero intermediate frequency satellite-signal after down coversion is averaged sampling and the cumulative operation of piece, obtain the zero intermediate frequency satellite-signal data of low sampling rate; Specifically: the long data of L millisecond of input are divided into the data block of L 1ms and superpose according to constant time range is corresponding;
The FFT module is connected with described average sample and piece accumulator module, and satellite-signal is carried out Fast Fourier Transform (FFT), carries out the search of code phase spectrum correlation;
The circular shifting module is connected with described FFT module, and the FFT Output rusults of satellite-signal is carried out Doppler's circular shifting, realizes the search to Doppler shift; Described this module comprises for 2 of the different starting points of generation of counting according to displacement
NThe circular shifting address generator of individual address, the read/write address generation rule of this circular shifting address generator is as follows: establish n and be the counting of displacement, n ∈ [10,10] is as n〉0 the time, start address start_address=2
N-n+1, when n＜0, start address start_address=-n;
The complex multiplier module is connected with described circular shifting module, for despreading that satellite-signal is multiplied each other;
Local PRN code FFT conjugation storer is connected with described complex multiplier module, for storing the result of getting conjugation after local PRN code FFT;
The IFFT module is connected with described complex multiplier module, is used for obtaining the correlated results of different code phases to taking advantage of again result to carry out reverse Fast Fourier Transform (FFT);
The differential coherence integration module is connected with described IFFT module, is used for the correlated results of different code phases is carried out the difference correlation energy accumulation;
Peak detection block is connected with described differential coherence integration module, is used for cumulative correlation energy peak value is detected, and realizes the output of satellite signal acquisition and Doppler shift and code phase;
Time-sequence control module, be connected with peak detection block with described Digital Down Converter Module, average sample and piece accumulator module, FFT module, circular shifting module, local PRN code FFT conjugation storer, complex multiplier module, IFFT module, differential coherence integration module, time-sequence control module is based on catches flow process and utilizes state machine to realize, in the control parameter of different State-output disparate modules, realize the workflow of whole system and the working state control of modules.
3. a kind of capture systems according to claim 2, it is characterized in that, described Digital Down Converter Module comprises: Direct Digital Frequency Synthesizers, be connected with the circular shifting module, and be used for producing the sine of certain frequency and cosine carrier signal as local carrier according to frequency control; Digital mixer is connected with described Direct Digital Frequency Synthesizers, is used for realizing the local intermediate frequency carrier that produces and the satellite intermediate frequency sampled data mixing of input.
4. a kind of capture systems according to claim 3, is characterized in that, described digital mixer is divided into I frequency mixer and Q frequency mixer according to in-phase component and quadrature component, I frequency mixer and Q frequency mixer respectively with the satellite intermediate frequency sampled data mixing of outside input.
5. a kind of capture systems according to claim 3, is characterized in that, described average sample and piece accumulator module comprise:
Data accumulator is connected with described digital mixer, is used for adding up to the input data;
2
NAddress generator is connected with described data accumulator, produces 2
NIndividual address is for the sampled data storer;
The sampled data storer is with described data accumulator, 2
NAddress generator is connected with the FFT module, is used for the satellite data after storage average sample and piece add up;
Data output switch, be connected with the sampled data storer with described data accumulator, be used for when carrying out the cumulative operation of piece, control the cumulative data of upper one-period that the sampled data storer is read and output in data accumulator with current zero intermediate frequency signals data and add up.
6. a kind of capture systems according to claim 2, is characterized in that, described circular shifting module comprises:
FFT real part storer is connected with described FFT module, is used for the real part data of storage FFT output;
FFT imaginary part storer is connected with described FFT module, is used for the imaginary data of storage FFT output;
The circular shifting address generator is connected with FFT imaginary part storer with described FFT real part storer, is used for counting according to displacement producing 2 of different starting points
NIndividual address.
7. a kind of capture systems according to claim 2, is characterized in that, described differential coherence integration module comprises:
The differential coherence processing module is connected with described IFFT, is used for relevant result is carried out the differential coherence operation;
Relevant real part storer, be connected with described differential coherence processing module, the real part data that are used for the relevant result of storage, these real part data are carried out with the relevant real part of next cycle in next differential coherence integration period is read out to the differential coherence processing module and are multiplied each other;
Relevant imaginary part storer as a result, be connected with described differential coherence processing module, the imaginary data that is used for the relevant result of storage, this imaginary data are carried out with the relevant imaginary part as a result of next cycle in next differential coherence integration period is read out to the differential coherence processing module and are multiplied each other;
The differential coherence result memory, be connected with peak detection block with described differential coherence processing module, be used for storage and send the differential coherence result data, the storage data are carried out cumulative with the differential coherence result of next cycle in next differential coherence integration period is read out to the differential coherence processing module.
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Families Citing this family (30)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102914782B (en) * | 2012-10-09 | 2014-12-31 | 暨南大学 | Rapid acquiring method suitable for GPS (Global Positioning System) weak signal |
| JP5835202B2 (en) * | 2012-12-14 | 2015-12-24 | ソニー株式会社 | Communication device |
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| CN103616702B (en) * | 2013-11-27 | 2017-01-11 | 中国科学院嘉兴微电子与系统工程中心 | High-sensitivity method and device for capturing Beidou satellite signals |
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| CN108061909A (en) * | 2017-11-23 | 2018-05-22 | 深圳开阳电子股份有限公司 | A kind of catching method, device and the satellite navigation receiver of GNSS satellite signal |
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| CN110764120B (en) * | 2019-11-07 | 2023-03-28 | 西安爱生技术集团公司 | High-sensitivity satellite navigation signal capturing method |
| CN111308517B (en) * | 2020-02-15 | 2023-06-02 | 中国科学院光电研究院 | Composite carrier extremely weak signal differential capturing method based on multiple correlators |
| CN112269195B (en) * | 2020-08-24 | 2023-12-12 | 江苏中智腾飞信息科技有限公司 | Beidou navigation signal correlation and capturing method and equipment thereof |
| CN113296129A (en) * | 2021-06-11 | 2021-08-24 | 合众思壮(河南)科技研究院有限公司 | Satellite signal capturing method and coherent integration post-processing device of satellite signal |
| CN114244384B (en) * | 2021-12-20 | 2023-06-16 | 浙江嘉科电子有限公司 | Continuous wave peak value capturing circuit and method for zero intermediate frequency receiver |
| CN114296109B (en) * | 2021-12-28 | 2023-03-24 | 汇鲲化鹏(海南)科技有限公司 | Baseband processing method and system for GNSS signal slice navigation data |
| CN114614860B (en) * | 2022-02-17 | 2023-06-23 | 中国电子科技集团公司第十研究所 | High-dynamic incoherent direct-spread signal differential capturing system |
| CN115291258B (en) * | 2022-10-08 | 2022-12-13 | 成都星航时空科技有限公司 | GNSS baseband capturing method |
| CN115426032B (en) * | 2022-11-03 | 2023-03-28 | 深圳比特微电子科技有限公司 | Signal capturing method and device |
| CN116347329B (en) * | 2022-12-16 | 2024-03-29 | 中交星宇科技有限公司 | Positioning signal capturing method and device, computing equipment and computer storage medium |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020053988A1 (en) * | 2000-11-03 | 2002-05-09 | Samsung Electronics Co., Ltd. | Method of improving the receiving performance for network-aided gps receiver |
| CN101063717A (en) * | 2006-04-24 | 2007-10-31 | 中国科学院微电子研究所 | Method for capturing GPS signal with FFT |
| CN101067651A (en) * | 2007-06-15 | 2007-11-07 | 西安华迅微电子有限公司 | GPS weak signal fast capturing realizing method |
| CN101666869A (en) * | 2009-09-21 | 2010-03-10 | 浙江大学 | Method and device for secondary capturing weak satellite navigation signals |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101625404B (en) * | 2008-07-09 | 2012-02-29 | 杭州中科微电子有限公司 | GPS signal large-scale parallel quick capturing method and module thereof |
-
2012
- 2012-03-09 CN CN 201210062429 patent/CN102608626B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020053988A1 (en) * | 2000-11-03 | 2002-05-09 | Samsung Electronics Co., Ltd. | Method of improving the receiving performance for network-aided gps receiver |
| CN101063717A (en) * | 2006-04-24 | 2007-10-31 | 中国科学院微电子研究所 | Method for capturing GPS signal with FFT |
| CN101067651A (en) * | 2007-06-15 | 2007-11-07 | 西安华迅微电子有限公司 | GPS weak signal fast capturing realizing method |
| CN101666869A (en) * | 2009-09-21 | 2010-03-10 | 浙江大学 | Method and device for secondary capturing weak satellite navigation signals |
Non-Patent Citations (1)
| Title |
|---|
| 适用于GPS软件接收机的弱信号捕获方法;黎山; 易清明; 陈庆; 石敏;《计算机应用》;20120301;第32卷(第3期);816-818，822 * |
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