CN101609139A - During catching, satellite navigation signals removes the method for text position influence - Google Patents
During catching, satellite navigation signals removes the method for text position influence Download PDFInfo
- Publication number
- CN101609139A CN101609139A CNA2009100413893A CN200910041389A CN101609139A CN 101609139 A CN101609139 A CN 101609139A CN A2009100413893 A CNA2009100413893 A CN A2009100413893A CN 200910041389 A CN200910041389 A CN 200910041389A CN 101609139 A CN101609139 A CN 101609139A
- Authority
- CN
- China
- Prior art keywords
- sequence
- random code
- chips
- pseudo
- text position
- 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.)
- Pending
Links
Images
Landscapes
- Position Fixing By Use Of Radio Waves (AREA)
Abstract
The present invention relates to the method that satellite navigation signals removes the text position influence in catching, expand the coherent integration time span to whole text bit length, acquisition sensitivity has improved 3dB, comprise step: produce the pseudo-random code data that number of chips equates with the contained number of chips in text position in this locality, and it is carried out zero padding operate, local pseudo-random code sequence PN length is 2 integral number power after the zero padding; Obtain sampled data that number of chips equates with PN sequence number of chips as the S sequence; Do the IFFT computing after the result who gets conjugation after the result of S sequence FFT computing for the first time and the computing of PN sequence FFT multiplied each other and obtain the R sequence; If R sequence maximal value has surpassed decision threshold, enter the tracking link; If R sequence maximal value does not surpass decision threshold, the S sequence is carried out the FFT computing second time, the computing starting point moves N chip, and N equals half of the contained number of chips in text position; Carry out the IFFT computing then, get new R sequence and do prize judgment.
Description
Technical field
The present invention relates to the satellite navigation positioning field, remove the method for text position influence during particularly a kind of satellite navigation signals is caught.
Background technology
To catching of satellite navigation signals is the two-dimensional search process of sign indicating number phase and frequency.Acquisition mode at satellite navigation signals can be divided into two kinds by detection method at present: coherent manner and incoherent mode.Gain promotes not quite incoherent mode to Signal Processing, and effect is relatively poor relatively; And coherent manner can provide very big processing gain, as shown in Figure 1.As seen from Figure 1, increase the coherent accumulation time span and can effectively improve the system handles gain, promptly improved the acquisition sensitivity of system; But coherence time, length was subjected to the influence of text position, as shown in Figure 2.As can be seen from Figure 2, probability and coherent accumulation time span that the text position occurs are linear, when reach 20ms coherence time, the text position must occur, the saltus step of text symbol occurs in coherent integration in the time, will cause decay to related power, has a strong impact on acquisition sensitivity.
Coherent manner commonly used has: parallel correlator technology, FFT (fast fourier transform) search technique and XFAST (Extended Replica Folding Acquisition Search Technique) etc.The consumption of parallel correlator technical resource is big, sign indicating number mutually and frequency can not parallel search, dynamic is poor; The FFT search technique resource with to sign indicating number mutually and obtained balance preferably between the parallel search of frequency, acquisition speed is fast, is widely used; The XFAST technology can improve the sign indicating number scope of search mutually, but influences acquisition sensitivity, is applicable to the occasion that carrier-to-noise ratio is higher.
In the FFT parallel search, pseudo-random code catching is a time-frequency search procedure, and its parallel search flow process as shown in Figure 3.For the cycle pseudo-random code sequence, the pseudo-random code search is equivalent to carry out the cyclic convolution computing, and the result that pseudo-random code is relevant is as follows:
Wherein S (i) is for receiving pseudo-random code sequence, and PN (i+m) is local pseudo-random code sequence, and N is the length of correlated series, m=0, and 1 ..., N-1.Convolution operation can realize that then the cyclic convolution result of cycle pseudo-random code sequence is by Fourier transform:
R (m)=IFFT (FFT (S) FFT
*(PN)) (formula 2)
Wherein, S is for receiving pseudo-random code sequence, and PN is local pseudo-random code sequence.Utilize the relevant result of fft algorithm computation cycles, can significantly improve the pseudo-random code search speed.
To handle the signal of being launched by gps satellite is example, in order to obtain the high processing gain, way commonly used is: the text bit length of GPS is 20ms, and sampled signal is divided by 10ms, 10ms at interval is one group, and the synoptic diagram of text position grouping as shown in Figure 4; Utilize the FFT parallel search method that the 10ms sampled data is carried out coherent integration then,, therefore in above-mentioned two groups of data one group of influence that does not comprise the text position must be arranged, can obtain the gain of 10dB because text position 20ms once; Again the integral result of interval 10ms is made noncoherent accumulation, further improve processing gain.The existing this technology of utilizing the FFT parallel search method to improve processing gain, because the influence of text position can not surpass half text position with the time span of coherent integration, the raising of processing gain has been subjected to bigger restriction.
Summary of the invention
The objective of the invention is to overcome the defective that processing gain in the existing catching method is subjected to the text position influence, provide a kind of in the satellite navigation signals acquisition procedure, remove the method for text position influence, this method is by the technological means of zero padding and mobile sampled data starting point, the time span of coherent integration is expanded to the length of whole text position, eliminated of the influence of text position, acquisition sensitivity has been improved 3dB correlated results.
Purpose of the present invention is achieved through the following technical solutions: the method that removes the text position influence during satellite navigation signals is caught, may further comprise the steps: step 1, produce the pseudo-random code data that number of chips equates with the contained number of chips in text position in this locality, and the pseudo-random code data are carried out zero padding operation, make that local pseudo-random code sequence length after the zero padding is 2 integral number power; Step 2 is obtained satellite signal samples data that the number of chips of the local pseudo-random code sequence after number of chips and the zero padding equates as receiving pseudo-random code sequence; Step 3 is done the IFFT computing with receiving after the result who gets conjugation after the result of pseudo-random code sequence FFT computing for the first time and the local pseudo-random code sequence FFT computing multiplies each other, and obtains the correlated results sequence; Step 4 is got the correlated results sequence and is done prize judgment: if the maximal value of correlated results sequence has surpassed decision threshold, then enters the tracking link; If the maximal value of correlated results sequence does not surpass decision threshold, then the sampled data that receives is carried out the FFT computing second time, the starting point of FFT computing is compared than the starting point of the FFT computing first time and has been moved N chip for the second time, and wherein N equals half of the contained number of chips in text position; Step 5 is done the IFFT computing after the result who gets conjugation after the result of the FFT computing second time of the sampled data that receives and the local pseudo-random code sequence FFT computing multiplied each other, and obtains new correlated results sequence; Get new correlated results sequence then and do prize judgment.
In the above-mentioned method that removes the text position influence, the local pseudo-random code sequence length after the described zero padding of step 1 equates with 2 integral number power greater than the minimum of the contained number of chips in text position.
In the above-mentioned method that removes the text position influence, the contained number of chips in text position is 20460, and the local pseudo-random code sequence length after the zero padding is 32768.
In the above-mentioned method that removes the text position influence, the zero-bit that the zero padding operation is mended is in the back of position, local pseudo-random code end.
The present invention has following advantage and effect with respect to prior art: on the basis based on the PN sign indicating number acquisition mode that has the FFT search technique now, making FFT length by zero padding is the form of 2 integral number power, be beneficial to and carry out the FFT computing, thereby carry out the FFT search first time, lock-on signal; If FFT searches for the lock-on signal that fails for the first time, then the starting point of sampled data is moved half of text bit length, carry out the FFT search second time again.Zero padding has extended time of coherent integration, has reduced the stepping of frequency search, makes frequency search more accurate; Before and after the chip lengths at starting point institute interval of twice search be half of text bit length, the inevitable complete 20ms sampled signal that is not subjected to the text position influence that once comprises in twice search procedure, thereby the length of coherent integration is expanded to the length of whole text position, eliminated of the influence of text position to correlated results, compare original mode, the acquisition sensitivity of satellite navigation signals has been improved 3dB.
Description of drawings
Fig. 1 is the graph of a relation of existing coherent accumulation length and processing gain;
Fig. 2 is the graph of a relation of existing text position probability of occurrence and coherent integration length;
Fig. 3 is existing parallel search process flow diagram based on FFT;
Fig. 4 is existing FFT search technique synoptic diagram to the grouping of text position when realizing that satellite navigation signals is caught;
Fig. 5 is the synoptic diagram of the present invention to the local code zero padding;
Fig. 6 is signal processing flow figure of the present invention;
Fig. 7 is the synoptic diagram with 10230 chips of sampled data starting point slip.
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 thereto.
Embodiment
With GPS is example, and when gps signal was carried out chip samples, a pseudo-random code contained 1023 chips at the 1ms Cycle Length, and a text position accounts for 20 pseudo-random code cycles, and then the 20ms sampled data is 20460 chips.In order to carry out the FFT computing, make sampled data length by the mode of zero padding is 2 integral number power.In the present embodiment, 20460 chips are contained in the text position, so we mend 12308 0 operation to local pseudo-random code, and the pseudo-random code length after the zero padding is equated with 2 integral number power greater than the minimum of the contained number of chips in text position, are 32768; Get 32768 satellite signal samples data simultaneously.Preferably, 10308 0 back that are positioned at position, local pseudo-random code end, as shown in Figure 5.
Treatment scheme of the present invention specifically comprises the steps: as shown in Figure 6
(1) produces the pseudo-random code data that number of chips equates with the contained number of chips in text position in this locality, and the pseudo-random code data are carried out zero padding operate, make that local pseudo-random code sequence length after the zero padding is 2 integral number power.
Because the text position contains 20460 chips, i.e. 20460 points, therefore the pseudo-random code data are mended 12308 zero after, the local pseudo-random code sequence PN (i) that is formed, i=0 wherein, 1 ... 32767, its length just is 15 powers of 2; 15 powers of 2 are that all are greater than in the contained number of chips 20460 in text position, minimum integral number power, just approach most the integral number power of the contained number of chips 20460 in text position, making convolution related operation amount not too big again when therefore making the FFT computing be easy to realize, is the preferred pseudo-random code sequence length of the present invention.In the present embodiment, local pseudo-random code sequence PN (i) is called for short the PN sequence.
(2) utilize sampling thief to obtain and the satellite signal samples data S (i) that equates with the number of chips of local pseudo-random code sequence of buffer memory number of chips, i=0 wherein, 1 ... 32767, S (i) sequence is called for short the S sequence in the present embodiment as receiving pseudo-random code sequence.Because the number of chips of the pseudo-random code sequence of present embodiment is 32768, so the contained number of chips of S sequence also is 32768.
(3) the S sequence is carried out the FFT computing first time, the PN sequence is carried out getting conjugation after the FFT computing, do the IFFT computing after for the first time FFT operation result and the PN sequence result that carries out getting after the FFT computing conjugation multiplies each other with the S sequence, obtain correlated results sequence R (m)=IFFT (FFT (S) FFT
*(PN)), m=0 wherein, 1 ... 32767.The correlated results sequence is called for short the R sequence in the present embodiment.
(4) get the R sequence and do prize judgment: if the maximal value of R sequence has surpassed decision threshold, acquisition success is described then, enters the tracking link.If the maximal value of R sequence does not surpass decision threshold, then the S sequence is carried out the FFT computing second time, the starting point of FFT computing is compared than the starting point of the FFT computing first time and has been moved N chip for the second time, wherein N equals half of text position number of chips, N=10230 in the present embodiment, as shown in Figure 7.
(5) do the IFFT computing after the result who gets conjugation after the result of S sequence FFT computing for the second time and the computing of PN sequence FFT is multiplied each other, obtain new R sequence; Get new R sequence then and do prize judgment.
The principle that the present invention removes the text position influence is as follows: because the text position may occur in the optional position of 32768 satellite sampled datas, a coherent integration process can not guarantee that complete 20ms satellite sampled signal and local pseudo-random code sequence are concerned with; Complete 20ms sampled data refers to there is not the text position influence in this 20ms.Be not subjected to the complete 20ms of text position influence to adopt data in order to guarantee to have in the coherent integration, we are with 10230 chips of sampled data starting point slip, as shown in Figure 7.The starting point of sampled data is slided behind 10230 chips backward, repeat above-mentioned FFT computing, multiply each other, the IFFT calculating process, carry out acquisition procedure again one time.The sampled data of twice acquisition procedure has 10230+32768=42998 chip, because 42998 greater than 20460*2=40920; So in 42998 chips of top twice search a complete 20ms must be arranged; After being concerned with, 20ms satellite sampled data that this is complete and local pseudo-random code sequence be used for doing prize judgment, whether surpassing decision threshold according to the result's of IFFT maximal value adjudicates, surpass threshold value and just enter tracking, otherwise the starting point of mobile sampled data is caught again.
By above-mentioned analysis as seen, the inevitable complete 20ms sampled signal that is not subjected to the text position influence that once comprise in twice search procedure of 10230 chips in interval, the length of coherent integration has just reached the length of a text position like this, than traditional coherent integration mode, the Signal Processing gain has been improved 3dB, and the sensitivity to signal capture has accordingly also improved 3dB.
Though said process is with the example that is captured as of the C/A of GPS, the range of application of this method not only is confined to this, to the C/A sign indicating number with GPS be the cycle sign indicating number of representative and with the P sign indicating number of GPS be representative the no periodic sign indicating number catch same being suitable for.
Claims (4)
1, remove the method for text position influence during satellite navigation signals is caught, it is characterized in that may further comprise the steps:
Step 1 produces the pseudo-random code data that number of chips equates with the contained number of chips in text position in this locality, and the pseudo-random code data is carried out zero padding operate, and makes that local pseudo-random code sequence length after the zero padding is 2 integral number power;
Step 2 is obtained satellite signal samples data that number of chips equates with the number of chips of local pseudo-random code sequence as receiving pseudo-random code sequence;
Step 3 is done the IFFT computing with receiving after the result who gets conjugation after the result of pseudo-random code sequence FFT computing for the first time and the local pseudo-random code sequence FFT computing multiplies each other, and obtains the correlated results sequence;
Step 4 is got the correlated results sequence and is done prize judgment: if the maximal value of correlated results sequence has surpassed decision threshold, then enters the tracking link; If the maximal value of correlated results sequence does not surpass decision threshold, then carry out the FFT computing second time to receiving pseudo-random code sequence, the starting point of FFT computing is compared than the starting point of the FFT computing first time and has been moved N chip for the second time, and wherein N equals half of the contained number of chips in text position;
Step 5 is done the IFFT computing with receiving after the result who gets conjugation after the result of pseudo-random code sequence FFT computing for the second time and the local pseudo-random code sequence FFT computing multiplies each other, and obtains new correlated results sequence; Get new correlated results sequence then and do prize judgment.
2, remove the method for text position influence during satellite navigation signals according to claim 1 is caught, it is characterized in that: the local pseudo-random code sequence length after the described zero padding of step 1 equates with 2 integral number power greater than the minimum of the contained number of chips in text position.
3, remove the method for text position influence during satellite navigation signals according to claim 2 is caught, it is characterized in that: the contained number of chips in text position is 20460, and the local pseudo-random code sequence length after the zero padding is 32768.
4, according to the method that removes the text position influence during each described satellite navigation signals is caught among the claim 1-3, it is characterized in that: the zero-bit that the zero padding operation is mended is in the back of position, local pseudo-random code end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2009100413893A CN101609139A (en) | 2009-07-24 | 2009-07-24 | During catching, satellite navigation signals removes the method for text position influence |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2009100413893A CN101609139A (en) | 2009-07-24 | 2009-07-24 | During catching, satellite navigation signals removes the method for text position influence |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101609139A true CN101609139A (en) | 2009-12-23 |
Family
ID=41482964
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2009100413893A Pending CN101609139A (en) | 2009-07-24 | 2009-07-24 | During catching, satellite navigation signals removes the method for text position influence |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101609139A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102193096A (en) * | 2010-02-23 | 2011-09-21 | 精工爱普生株式会社 | Signal acquisition method and signal acquisition apparatus |
| CN107272029A (en) * | 2016-04-06 | 2017-10-20 | 大唐半导体设计有限公司 | A kind of method and apparatus for capturing navigation signal |
-
2009
- 2009-07-24 CN CNA2009100413893A patent/CN101609139A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102193096A (en) * | 2010-02-23 | 2011-09-21 | 精工爱普生株式会社 | Signal acquisition method and signal acquisition apparatus |
| CN107272029A (en) * | 2016-04-06 | 2017-10-20 | 大唐半导体设计有限公司 | A kind of method and apparatus for capturing navigation signal |
| CN107272029B (en) * | 2016-04-06 | 2021-02-05 | 大唐半导体设计有限公司 | Method and device for capturing navigation signal |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110114696B (en) | Signal acquisition method and receiver for satellite navigation system | |
| CN100539457C (en) | The double-folding capture searching method of long-period spread spectrum code | |
| CN102662183B (en) | Method and system for global position system (GPS) signal capture | |
| CN101324658B (en) | Method for capturing full bit of GPS weak signal | |
| CN100553168C (en) | A kind of frequency folding time frequency parallel searching method of long-period spread spectrum code | |
| CN103091687B (en) | Big dipper receiver multi-satellite signal joint capturing method | |
| CN104280750A (en) | Long code capture system and method based on partial matched filtering FFT algorithm | |
| CN106230475B (en) | One kind being based on Tong detectors pseudo-code Doppler effect correction catching method and device | |
| CN108169772B (en) | Satellite signal capturing method of windowed FFT (fast Fourier transform) | |
| CN106707309B (en) | A kind of smart method for catching of carrier wave pseudo-code two-dimensional search | |
| CN105911569A (en) | Beidou navigation system B1 frequency band weak D1 signal capture method based on code element sequence estimation | |
| CN104459734B (en) | Beidou satellite navigation signal capturing method based on NH code element jumping detection | |
| CN105607088A (en) | Rapid guiding tracking device for satellite navigation multifrequency receiver signals | |
| CN104570017A (en) | Avoiding and stripping method for Neumann-Hoffman codes in navigation messages of Beidou navigation satellite system D1 | |
| CN105759288A (en) | Feature sequence-based Beidou B1I weak signal acquisition method | |
| CN106291610A (en) | A kind of parallel correlation module of compression for GNSS signal compression capture processing means and its implementation | |
| CN103926604A (en) | Weak signal capturing method based on overlapping difference cycle coherent integration | |
| CN103197328B (en) | High dynamic satellite receiver fast capture method based on 2 ms data storage | |
| CN104035109B (en) | Weak signal catching method based on overlapping 1/5 bit difference circulation coherent integration | |
| CN103941269A (en) | PN code capturing method used for satellite navigation system | |
| CN103760578B (en) | A kind of GNSS satellite navigation signal without fuzzy tracking method | |
| CN102680988B (en) | High-sensitivity navigation satellite signal nonlinear acquiring method and device | |
| CN102707297A (en) | Method for fast capturing COMPASS signal | |
| CN103969664B (en) | A kind of GPS weak signal catching method circulating coherent integration based on difference | |
| CN101609139A (en) | During catching, satellite navigation signals removes the method for text position influence |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Open date: 20091223 |