CN107317600A - A kind of acquiring pseudo code of spread-spectrum signal and tracking system and method - Google Patents
A kind of acquiring pseudo code of spread-spectrum signal and tracking system and method Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
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Abstract
The invention belongs to spread spectrum technic field, a kind of acquiring pseudo code of spread-spectrum signal and tracking system and method are disclosed, including：Data cache module, capture correlator, capture FFT judge modules, real time data update module, tracking correlator, tracking FFT judge modules, capture pseudo-code phase adjusting module, capture pseudo-code generation module, tracking pseudo-code phase adjusting module and tracking pseudo-code generation module；Because the information code of transmitting terminal is one-to-one with pseudo-code, in receiving terminal, pseudo-code phase is consistent with the pseudo-code phase that transmitting terminal is modulated, and during acquiring pseudo code with tracking, the local pseudo-code phase of receiving terminal keeps constant, it is bigger than the value that the catching method of traditional mobile pseudo-code is obtained by the cumulative obtained value of integration after the local pseudo-code of receiving terminal is with inputting the PN synchronization in spread-spectrum signal；Acquiring pseudo code and the ability of tracking are improved, the demodulation after despreading is also beneficial to, and then improve detecting and tracking ability of the reception system to spread-spectrum signal.
Description
Technical field
The invention belongs to spread spectrum technic field, more particularly to a kind of acquiring pseudo code of spread-spectrum signal and tracking system and
Method, it is adaptable to the acquiring pseudo code of the Direct Sequence Spread Spectrum Signal in spread spectrum communication and tracking.
Background technology
Communication environment it is complicated and changeable, higher requirement, spread spectrum communication skill are proposed in terms of anti-interference, information privacy
Advantage of the art in these two aspects so that be applied widely in moving communicating field and satellite communication field.In spread spectrum communication
In system, spread-spectrum signal track receiver is one of important branch, and its ability detected to spread-spectrum signal has reacted expansion
The development of the frequency communication technology., it is necessary to be de-spread with transmitting terminal identical pseudo-code in band spread receiver, the shadow of pseudo-code is eliminated
Ring, extract raw information code signal；Because the bandwidth of spread-spectrum signal is very big, power spectral density very little, so in anti-interference and letter
There are outstanding advantages in terms of ceasing secrecy.
Method for acquiring pseudo code has serial acquisition, parallel capture, matched filtering etc. several.
Serial acquisition method is embodied as：Data of the related PN-code capture that adds up every time, related accumulated result with
Thresholding is contrasted, and more than thresholding then acquisition success, the phase that pseudo-code otherwise is moved into half of pseudo- code length continues related cumulative.But
Capture time is longer, and the time is not fixed, when a pseudo-code (PN-code capture is many at least comprising how many pseudo-codes) sampling one
During point, the time is very fast, but increasing with pseudo-code sampling number, and related accumulation length is multiplied, capture time into
Increase again.
Parallel acquiring pseudo code is embodied as：If PN-code capture is N, need first to store the pseudo-code that the 2N group cycles are N, often
The phase of half of pseudo- code length is differed between two adjacent groups.Input signal is simultaneously related to this 2N group pseudo-code cumulative, and consumption is a large amount of
Resource, if PN-code capture is shorter (such as PN-code capture 31), consumption resource it is less, oversize (the such as PN-code capture of pseudo-code
1023) resource then can largely be taken.
Matched filtering catching method is embodied as：As FIR filter structure, but coefficient is pseudo-code, although capture time
Comparatively fast, consumption resource is less, but with the change of a pseudo-code sampling number, its adaptability is very poor.
More than several existing methods have the shortcomings that one it is common, i.e., it must be maximum that can not ensure the related energy added up
, when information code saltus step ,+1 becomes -1, if related cumulative length just includes half+1, half -1, then related cumulative knot
Fruit is 0, and energy is minimum.
The content of the invention
For the shortcoming of above-mentioned prior art, it is an object of the invention to provide a kind of acquiring pseudo code of spread-spectrum signal with
Track system and method, it is possible to increase the capture of pseudo-code and tracking performance.
To reach above-mentioned purpose, the present invention, which is adopted the following technical scheme that, to be achieved.
Technical scheme one：
The acquiring pseudo code and tracking system of a kind of spread-spectrum signal, the system include：Data cache module, capture are related
Device, capture FFT judge modules, real time data update module, tracking correlator, tracking FFT judge modules, capture pseudo-code phase are adjusted
Mould preparation block, capture pseudo-code generation module, tracking pseudo-code phase adjusting module and tracking pseudo-code generation module；
Wherein, signal input part, feedback signal input terminal and signal output part are provided with the data cache module,
Signal input part, preset signal input and signal output part, the capture pseudo-code production are provided with the capture correlator
It is provided with raw module on preset signal output end, the capture FFT judge modules and is provided with signal input part, signal output part
And feedback signal output, feedback signal input terminal is provided with the capture pseudo-code phase adjusting module and feedback signal is defeated
Go out end；
The first signal input part, secondary signal input, feedback signal are provided with the real time data update module defeated
Enter to hold and signal output part, it is defeated to be provided with signal input part, preset signal input and signal on the tracking correlator
Go out to be provided with preset signal output end, the tracking FFT judge modules on end, the tracking pseudo-code generation module and be provided with letter
Feedback signal input terminal and feedback are provided with number input and feedback signal output, the tracking pseudo-code phase adjusting module
Signal output part.
The characteristics of technical solution of the present invention one and further it is improved to：
The signal input part of the data cache module is used to input spread-spectrum signal；The signal of the data cache module is defeated
Go out end and be connected with capturing the signal input part of correlator, capture the letter of the signal output part and capture FFT judge modules of correlator
The connection of number input, captures the feedback signal of the feedback signal output and capture pseudo-code phase adjusting module of FFT judge modules
Input is connected, and captures the feedback signal output of pseudo-code phase adjusting module and the feedback signal input terminal of data cache module
Connection；The preset signal output end of the capture pseudo-code generation module is connected with capturing the preset signal input of correlator；
First signal input part of the real time data update module is used to input spread-spectrum signal；Real time data update module
Secondary signal input with capture FFT judge modules signal output part be connected, the signal output of real time data update module
Hold and be connected with tracking the signal input part of correlator, track the signal of the signal output part and tracking FFT judge modules of correlator
Input is connected, and the feedback signal output for tracking FFT judge modules and the feedback signal for tracking pseudo-code phase adjusting module are defeated
Enter end connection, track the feedback signal output of pseudo-code phase adjusting module and inputted with the feedback signal of real time data update module
End connection；The preset signal output end of the tracking pseudo-code generation module is connected with tracking the preset signal input of correlator.
Technical scheme two：
The acquiring pseudo code and tracking of a kind of spread-spectrum signal, the spread-spectrum signal refer to modulate after pseudo-code in information code
Signal, and the pseudo-code be period code, produced by shift register, if number of shift register stages be n, then modulate a cycle
2 are included in the spread-spectrum signal of pseudo-coden- 1 pseudo-code, the sampling of M points is carried out to each pseudo-code, then from modulation a cycle pseudo-code
Sampling obtains (2 in spread-spectrum signaln- 1) × M sampled data；Methods described comprises the following steps：
Step 1, the sampled data of two PN-code captures, common (2 are cached in data cache modulen- 1) × M × 2 hits
According to the sampled data of described two PN-code captures is obtained data of being sampled from spread-spectrum signal；
Step 2, capture correlator obtains 2 from the data cache modulen× M sampled data, and from the capture
Pseudo-code generation module obtains local pseudo-code sequence；The local pseudo-code sequence includes 2n- 1 data；
By described 2n× M sampled data is divided into 2nSection, every section of sampled data length is M, by the M sampled data and
A data in local pseudo-code sequence, which are multiplied, obtains M multiplied result data, then by M obtained multiplied result data accumulation
Obtain an accumulation result data；So as to obtain 2nIndividual accumulation result data, and by described 2nIndividual accumulation result data are sent to catching
Obtain FFT judge modules；
Step 3, capture FFT judge modules are to described 2nIndividual accumulation result data carry out 2nThe FFT of point, obtains FFT changes
Result is changed, and obtains the maximum in FFT result；
Capture FFT judge modules driving capture pseudo-code phase adjusting module, make sampled data in data cache module to
The sampled data of half of pseudo- code length is moved right, described half pseudo- code length is M/2；
Step 4, step 2 and step 3 totally 2 × (2 is repeatedn- 1) it is secondary, so as to obtain 2 in capture FFT judge modules
×(2n- 1) individual maximum；
Determine described 2 × (2n- 1) average of individual maximum, and by described 2 × (2n- 1) average of individual maximum is designated as entirely
Office's average value；And determine described 2 × (2n- 1) maximum in individual maximum, and by described 2 × (2n- 1) in individual maximum most
Big value is designated as global maximum；
If the global maximum is more than P times of global mean value, P is the integer more than 1, it is determined that realizes pseudo-code and catches
Obtain, so as to obtain the phase offset between local pseudo-code sequence and input spread-spectrum signal, pseudo-code tracing is carried out into step 5；
Otherwise, the sampled data of two PN-code captures cached in the data cache module is emptied, again order buffer
The sampled data of two PN-code captures, and return to step 2；
Step 5, real time data update module is adjusted according to the phase offset between local pseudo-code sequence and input spread-spectrum signal
The phase of the sampled data of the spread-spectrum signal of whole acquisition, and M sampled data is sent every time to tracking correlator；
Step 6, tracking correlator obtains three tunnel pseudo-codes from the tracking pseudo-code generation module, and three tunnel pseudo-code is wrapped respectively
Include：Advanced code, i.e. time-code and delayed code, described half of pseudo- code length of the i.e. delayed advanced code of time-code, the delayed code are delayed immediately
Half of pseudo- code length of code；
Three branch roads, respectively advanced branch road, instant branch road and delayed branch road are provided with the tracking correlator；It is described
Advanced branch road is used to carry out the associative operation that correlation length is M to M sampled data and the advanced code, obtains an advanced branch
The accumulated value on road, the instant branch road is used to carry out related behaviour of the correlation length for M to M sampled data and the i.e. time-code
Make, obtain the accumulated value of an instant branch road, the delayed branch road is used to carry out correlation length to M sampled data and delayed code
For M associative operation, the accumulated value of a delayed branch road is obtained, and the accumulated value of each branch road is sent to tracking FFT judgements
Module；
Step 7, when the tracking FFT judge modules obtain three branch roads are sent respectively 2nAfter individual accumulated value, to advanced
The 2 of branch road transmissionnIndividual accumulated value carries out 2nThe FFT of point, obtains the maximum of advanced branch road in FFT result, to delayed
The 2 of branch road transmissionnIndividual accumulated value carries out 2nThe FFT of point, obtains the maximum of delayed branch road in FFT result, described to be
The 2 of Shi Zhilu transmissionsnIndividual accumulated value is to remove the information code after pseudo-code, is used as last output；
Step 8, if the maximum of advanced branch road is more than the maximum of delayed branch road in FFT result in FFT result
Value, then track FFT judge modules driving tracking pseudo-code phase adjusting module by the delayed sampled point of real time data update module；
If the maximum of advanced branch road is less than the maximum of delayed branch road in FFT result in FFT result, with
Track FFT judge modules driving tracking pseudo-code phase adjusting module is by the super previous sampled point of real time data update module, to sampling
Pseudo-code in data is tracked.
The characteristics of technical solution of the present invention two and further it is improved to：
(1) in step 4, step 2 and step 3 totally 2 × (2 is repeatedn- 1) during secondary,
Taking-up 2 correlator the 1st time is captured at the address 0 in data cache modulen× M sampled datas, capture phase
Taking-up 2 device the 2nd time is closed at the address M/2 in data cache modulen× M sampled datas, until capture correlator the 2nd ×
(2n- 1) the secondary address [2 × (2 from data cache modulen- 1) 2 are taken out at -1] × M/2n× M sampled datas.
(2) in step 4, the phase offset between local pseudo-code sequence and input spread-spectrum signal is obtained, is specially：
If the global maximum is 2 × (2n- 1) l-th in individual maximum, then local pseudo-code sequence is with inputting spread spectrum
Phase offset between signal is (L-1) × M/2.
In the acquiring pseudo code stage, due to first storing the input spread-spectrum signal of sampling in memory, so the speed of access
Degree can be improved, and the speed of corresponding relevant treatment, FFT processing etc. can be accelerated, and can thus shorten the acquiring pseudo code time.By
Keep constant in the pseudo-code phase of this research implementation method, after local pseudo-code is synchronous with input spread-spectrum signal, what FFT was handled is
The continuous complete PN-code capture data of one pseudo-code phase, so accumulation energy reaches maximum, further improve acquiring pseudo code
Ability.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is the accompanying drawing used required in technology description to be briefly described, it should be apparent that, drawings in the following description are only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with
Other accompanying drawings are obtained according to these accompanying drawings.
Fig. 1 for the present invention acquiring pseudo code with tracking realize block diagram.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.It is based on
Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under the premise of creative work is not made
Embodiment, belongs to the scope of protection of the invention.
Pseudo-code is produced by shift register, it is assumed that register series is n, then the pseudo- code length (cycle) produced is
2n- 1 (i.e. one PN-code capture includes 2n- 1 pseudo-code), it is assumed that M point of a pseudo-code sampling (is determined by sample rate with pseudo- bit rate
It is fixed), then a PN-code capture sampling (2n- 1) × M data.Because FFT treated lengths generally are 2n, so according to pseudo-code week
The selection of FFT treated lengths is one more than PN-code capture in phase, the embodiment of the present invention, i.e. the length selection of FFT processing is 2n, the puppet
Code acquisition and the method for tracking, comprise the following steps：
Step 1, data cache module caches the sampled data of two PN-code captures, is analyzed more than, FFT treated lengths
For 2n, so taking out 2 from data cache module every timen× M sampled data and the pseudo-code that capture pseudo-code generation module is produced are common
Correlation is carried out into capture correlator, correlation length is a pseudo-code, i.e., by 2 in capture correlatorn× M sampled data point
For 2nSection, is M per segment length, every M sampled data is first multiplied with a sampled point of local pseudo-code, then this M is sampled
Data accumulation, capture correlator output 2nIndividual result send capture FFT judge modules, and capture FFT judge modules carry out 2nPoint
FFT processing, and record this maximum；
Capture FFT judge modules drive capture pseudo-code phase adjusting module to make the sampling number in data cache module simultaneously
According to the sampled data (i.e. M/2) for half of the pseudo- code length that moves right, and take out 2 from data cache module againn× M hits
According to, send capture correlator, capture FFT judge modules etc. to be handled, and record secondary FFT result maximum, repeat with
Upper step carries out 2 × (2 altogethern- 1) it is secondary, fetch, opened for the second time from address M/2 since the address 0 of data cache module for the first time
Beginning access ..., the 2nd × (2n- 1) it is secondary from address [2 × (2n- 1) -1] × M/2 access.2 are taken out every timen× M hits
According to.Obtain 2 × (2n- 1) individual FFT result maximum again capture FFT judge modules find this 2 × (2n- 1) maximum of individual result
Value and average.And by maximum and average ratio compared with when maximum is more than P (integer for being more than 1) times of average, that is, thinking to realize
Acquiring pseudo code, into pseudo-code tracing process, obtains the phase offset between local pseudo-code and input spread-spectrum signal, 2 × (2n-1)
In individual value, which time FFT result is maximum be, then the phase offset between corresponding local pseudo-code and input spread-spectrum signal is just
Which time starts the address value of access, for example, it is assumed that the FFT result of the L time is maximum, then local pseudo-code with input spread-spectrum signal it
Between phase offset just be (L-1) × M/2, its fetch address also be (L-1) × M/2.Step is performed after acquiring pseudo code success
2；Otherwise the sample point data continuation above step that data cache module caches two PN-code captures again is emptied.
Step 2, the local pseudo-code that real time data update module is obtained according to acquiring pseudo code part and input spread-spectrum signal it
Between phase offset, adjustment real time data phase to reach acquiring pseudo code purpose, implement as the sampling according to phase offset
Points, wait for tracking pseudo-code generation module in several clock cycle and do not export pseudo-code, then exported from tracking pseudo-code generation module
Pseudo-code.
Track pseudo-code generation module and produce advanced, instant, delayed three tunnel pseudo-code, be referred to as advanced code, i.e. time-code, delayed
Code, what is directly exported is just advanced code, i.e. time-code half of pseudo-code phase of delayed advanced code, delayed i.e. half of the pseudo-code of time-code of delayed code
Phase, three tunnel pseudo-codes respectively to input spread-spectrum signal tracking correlator in it is related, be referred to as advanced branch road, instant branch road,
Delayed branch road, correlation length is puppet code length, i.e. a M；First it is multiplied per M sampled data in tracking correlator with pseudo-code,
Add up again, output enters tracking FFT judge modules, when obtaining 2nIndividual accumulated value, in tracking FFT judge modules, advanced branch road,
Delayed branch road carries out 2 respectivelynPoint FFT processing, obtains FFT result and the advanced branch road of comparison, delayed branch road FFT result maximum,
If be more than in advance it is delayed if driving tracking pseudo-code phase adjusting module by the delayed sampled point of real time data update module；Such as
Fruit is less than delayed then driving tracking pseudo-code phase adjusting module by the super previous sampled point of real time data update module in advance；The mistake
Cheng Yizhi is in dynamic adjustment.The output for tracking instant branch road in correlator is exactly to remove the signal after pseudo-code.
In the acquiring pseudo code stage, due to first storing the input spread-spectrum signal of sampling in memory, so the speed of access
Degree can be improved, and the speed of corresponding relevant treatment, FFT processing etc. can be accelerated, and can thus shorten the acquiring pseudo code time.By
In implementation method of the embodiment of the present invention, pseudo-code phase keeps constant, after local pseudo-code is synchronous with input spread-spectrum signal, FFT
What is handled is the data of a complete PN-code capture, and pseudo-code phase is continuous, so accumulation energy reaches maximum, is further improved
The ability of acquiring pseudo code.
Exemplary, if sample rate 60MHz, pseudo- bit rate 5MHz, PN-code capture 1023 a, pseudo-code is sampled 12 points.Ginseng
It is that block diagram is realized in acquiring pseudo code and the tracking of the present invention according to Fig. 1；The acquiring pseudo code and the implementation method of tracking, including：Number
According to cache module, capture pseudo-code generation module, capture pseudo-code phase adjusting module, capture FFT judge modules, capture correlator,
Correlator, tracking pseudo-code generation module, tracking pseudo-code phase adjusting module, tracking FFT judge modules, real time data is tracked to update
Module；The acquiring pseudo code and tracking, comprise the following steps：
Step 1, acquiring pseudo code is carried out first, and pseudo-code tracing is carried out after acquiring pseudo code success.Data cache module caching two
The sampled data of individual PN-code capture, is analyzed more than, and FFT treated lengths are 1024, so being taken every time from data cache module
Go out 1024*12 sampled data and enter capture related, the phase of correlator progress jointly to the pseudo-code that capture pseudo-code generation module is produced
Customs director's degree is that 12 sampled points of a pseudo-code are long, i.e., 1024*12 sampled data is divided into 1024 sections in capture correlator, often
Segment length is 12, and every 12 sampled datas are first multiplied with a sampled point of pseudo-code, then this 12 sampled datas are added up, and is caught
Obtain 1024 results of correlator output and send capture FFT judge modules, capture FFT judge modules are carried out at 1024 points of FFT
Reason, and record this maximum；
Capture FFT judge modules drive capture pseudo-code phase adjusting module to make the sampling number in data cache module simultaneously
According to the sampled data (i.e. 6) for half of the pseudo- code length that moves right, and take out 1024*12 sampling from data cache module again
Data, send capture correlator, capture FFT judge modules etc. to be handled, and record secondary FFT result maximum, repeat
Upper step 2046 time, fetches since the address 0 of data cache module for the first time, second access ..., the since address 6
2046 times from address 2045*6 fetch.1024*12 sampled data is taken out every time.Obtain 2046 FFT result maximums again
The maximum and average of this 2046 results are found in capture FFT judge modules.And by maximum and average ratio compared with working as maximum
During more than 8 times of averages, that is, think to realize acquiring pseudo code, into pseudo-code tracing process, obtain local pseudo-code and input spread spectrum letter
Phase offset between number, acquiring pseudo code successful execution step 2；Otherwise empty data cache module and cache two PN-code captures again
Sample point data continue above step.
Specifically, it is assumed that the Direct Sequence Spread Spectrum Signal of input is E (t), its expression formula is：
Wherein, A is signal amplitude, and ω is angular speed,For difference, t represents time variable, and c (t) is pseudo-code, and value is+1
Or -1.
Acquiring pseudo code and the purpose of tracking are exactly in order to copy c (t), if the pseudo-code c ' (t) replicated and c (t) is completely
It is consistent then pseudo-code c (t) can be eliminated, reach the purpose of despreading.Capture makes c ' (t) differ most half pseudo- code length phases with c (t)
Position, tracking makes c ' (t) basically identical with c (t).
Step 2, the local pseudo-code that real time data update module is obtained according to acquiring pseudo code part and input spread-spectrum signal it
Between phase offset, adjustment real time data phase to reach acquiring pseudo code purpose, implement as the sampling according to phase offset
Points, wait for several clock cycle, then export pseudo-code from tracking pseudo-code generation module.
Track pseudo-code generation module and produce advanced, instant, delayed three tunnel pseudo-code, be referred to as advanced code, i.e. time-code, delayed
Code, what is directly exported is just advanced code, i.e. time-code half of pseudo-code phase of delayed advanced code, delayed i.e. half of the pseudo-code of time-code of delayed code
Phase, three tunnel pseudo-codes respectively to input spread-spectrum signal tracking correlator in it is related, be referred to as advanced branch road, instant branch road,
Delayed branch road, correlation length is pseudo- code length, i.e., 12；Every 12 sampled datas elder generation and pseudo- code-phase in tracking correlator
Multiply, then add up, output enters tracking FFT judge modules, when obtaining 1024 accumulated values, in tracking FFT judge modules, in advance
Branch road, delayed branch road carry out 1024 point FFT processing respectively, obtain FFT result and the advanced branch road of comparison, delayed branch road FFT result
Maximum, if in advance be more than it is delayed if driving tracking pseudo-code phase adjusting module real time data update module is adopted for delayed one
Sampling point；If be less than in advance it is delayed if driving tracking pseudo-code phase adjusting module by the super previous sampling of real time data update module
Point；The process is always in dynamic adjustment.The output for tracking instant branch road in correlator is exactly to remove the signal after pseudo-code.
Step 3, whether acquiring pseudo code succeeds with tracking, and the dynamic tracking of pseudo-code is kept if success；Otherwise, step is returned
Rapid 1, above-mentioned steps are circulated, until local pseudo-code and the PN synchronization in input Direct Sequence Spread Spectrum Signal.
Because the information code of transmitting terminal is one-to-one with pseudo-code, in receiving terminal, pseudo-code phase is modulated with transmitting terminal
Pseudo-code phase is consistent, and during acquiring pseudo code with tracking, the local pseudo-code phase of receiving terminal keeps constant, so finally working as
The local pseudo-code of receiving terminal by the cumulative obtained value of integration with after the PN synchronization in input spread-spectrum signal, generally all comparing
The catching method of traditional mobile pseudo-code is big.Acquiring pseudo code and the ability of tracking are not only increased, while being more favorable to despreading
Demodulation afterwards, and then improve detecting and tracking ability of the reception system to spread-spectrum signal.
One of ordinary skill in the art will appreciate that：Realizing all or part of step of above method embodiment can pass through
Programmed instruction related hardware is completed, and foregoing program can be stored in computer read/write memory medium, and the program exists
During execution, the step of execution includes above method embodiment；And foregoing storage medium includes：ROM, RAM, magnetic disc or CD
Etc. it is various can be with the medium of store program codes.
The foregoing is only a specific embodiment of the invention, but protection scope of the present invention is not limited thereto, any
Those familiar with the art the invention discloses technical scope in, change or replacement can be readily occurred in, should all be contained
Cover within protection scope of the present invention.Therefore, protection scope of the present invention should be based on the protection scope of the described claims.
Claims (5)
1. the acquiring pseudo code and tracking system of a kind of spread-spectrum signal, it is characterised in that the system includes：Data cache module,
Correlator is captured, FFT judge modules, real time data update module is captured, tracks correlator, tracking FFT judge modules, captures pseudo-
Code phase adjusting module, capture pseudo-code generation module, tracking pseudo-code phase adjusting module and tracking pseudo-code generation module；
Wherein, signal input part, feedback signal input terminal and signal output part are provided with the data cache module, it is described
Signal input part, preset signal input and signal output part are provided with capture correlator, the capture pseudo-code produces mould
Be provided with block on preset signal output end, the capture FFT judge modules be provided with signal input part, signal output part and
Feedback signal input terminal and feedback signal output are provided with feedback signal output, the capture pseudo-code phase adjusting module
End；
The first signal input part, secondary signal input, feedback signal input terminal are provided with the real time data update module
And signal output part, signal input part, preset signal input and signal output part are provided with the tracking correlator,
It is provided with preset signal output end, the tracking FFT judge modules that to be provided with signal defeated on the tracking pseudo-code generation module
Enter and be provided with feedback signal input terminal and feedback signal on end and feedback signal output, the tracking pseudo-code phase adjusting module
Output end.
2. the acquiring pseudo code and tracking system of a kind of spread-spectrum signal according to claim 1, it is characterised in that
The signal input part of the data cache module is used to input spread-spectrum signal；The signal output part of the data cache module
It is connected with the signal input part for capturing correlator, the signal output part for capturing correlator and the signal for capturing FFT judge modules are defeated
Enter end connection, the feedback signal for capturing the feedback signal output and capture pseudo-code phase adjusting module of FFT judge modules is inputted
End connection, captures the feedback signal output of pseudo-code phase adjusting module and the feedback signal input terminal of data cache module connects
Connect；The preset signal output end of the capture pseudo-code generation module is connected with capturing the preset signal input of correlator；
First signal input part of the real time data update module is used to input spread-spectrum signal；The of real time data update module
Binary signal input with capture FFT judge modules signal output part be connected, the signal output part of real time data update module and
The signal input part connection of correlator is tracked, the signal for tracking the signal output part and tracking FFT judge modules of correlator is inputted
End connection, tracks the feedback signal input terminal of the feedback signal output and tracking pseudo-code phase adjusting module of FFT judge modules
Connection, tracks the feedback signal output of pseudo-code phase adjusting module and connects with the feedback signal input terminal of real time data update module
Connect；The preset signal output end of the tracking pseudo-code generation module is connected with tracking the preset signal input of correlator.
3. the acquiring pseudo code and tracking of a kind of spread-spectrum signal, it is characterised in that the spread-spectrum signal refers in information code
The signal after pseudo-code is modulated, and the pseudo-code is period code, if including 2 in the spread-spectrum signal of one PN-code capture of modulationn- 1
Pseudo-code, the sampling of M points is carried out to each pseudo-code, then sampling obtains (2 from the spread-spectrum signal of one PN-code capture of modulationn-1)×
M sampled data；Methods described comprises the following steps：
Step 1, the sampled data of two PN-code captures, common (2 are cached in data cache modulen- 1) × M × 2 sampled data, institute
The sampled data for stating two PN-code captures is obtained data of being sampled from spread-spectrum signal；
Step 2, capture correlator obtains 2 from the data cache modulen× M sampled data, and produced from the capture pseudo-code
Raw module obtains local pseudo-code sequence；The local pseudo-code sequence includes 2n- 1 data；
By described 2n× M sampled data is divided into 2nSection, every section of sampled data length is M, by the M sampled data and locally
A data in pseudo-code sequence, which are multiplied, obtains M multiplied result data, then M obtained multiplied result data accumulation is obtained
One accumulation result data；So as to obtain 2nIndividual accumulation result data, and by described 2nIndividual accumulation result data are sent to capture
FFT judge modules；
Step 3, capture FFT judge modules are to described 2nIndividual accumulation result data carry out 2nThe FFT of point, obtains FFT knot
Really, and the maximum in FFT result is obtained；
FFT judge modules driving capture pseudo-code phase adjusting module is captured, the sampled data in data cache module is moved right
The sampled data of dynamic half of pseudo- code length, described half pseudo- code length is M/2；
Step 4, step 2 and step 3 totally 2 × (2 is repeatedn- 1) it is secondary, so as to obtain 2 × (2 in capture FFT judge modulesn-
1) individual maximum；
Determine described 2 × (2n- 1) average of individual maximum, and by described 2 × (2n- 1) average of individual maximum is designated as global flat
Average；And determine described 2 × (2n- 1) maximum in individual maximum, and by described 2 × (2n- 1) maximum in individual maximum
It is designated as global maximum；
If the global maximum is more than P times of global mean value, P is the integer more than 1, it is determined that realize acquiring pseudo code,
So as to obtain the phase offset between local pseudo-code sequence and input spread-spectrum signal, pseudo-code tracing is carried out into step 5；
Otherwise, the sampled data of two PN-code captures cached in the data cache module is emptied, again order buffer two
The sampled data of PN-code capture, and return to step 2；
Step 5, real time data update module is according to the phase offset between local pseudo-code sequence and input spread-spectrum signal, and adjustment is obtained
The phase of the sampled data of the spread-spectrum signal taken, and M sampled data is sent every time to tracking correlator；
Step 6, tracking correlator obtains three tunnel pseudo-codes from the tracking pseudo-code generation module, and three tunnel pseudo-code includes respectively：
Advanced code, i.e. time-code and delayed code, described half of pseudo- code length of the i.e. delayed advanced code of time-code, the delayed i.e. time-code half of the delayed code
Individual pseudo- code length；
Three branch roads, respectively advanced branch road, instant branch road and delayed branch road are provided with the tracking correlator；It is described advanced
Branch road is used to carry out M sampled data and the advanced code associative operation of the correlation length for M, obtains advanced branch road
Accumulated value, the instant branch road is used to carry out the associative operation that correlation length is M with the i.e. time-code to M sampled data, obtains
To the accumulated value of an instant branch road, it is M's that the delayed branch road, which is used to carry out correlation length to M sampled data and delayed code,
Associative operation, obtains the accumulated value of a delayed branch road, and the accumulated value of each branch road is sent to tracking FFT judge modules；
Step 7, when the tracking FFT judge modules obtain three branch roads are sent respectively 2nAfter individual accumulated value, advanced branch road is sent out
2 sentnIndividual accumulated value carries out 2nThe FFT of point, obtains the maximum of advanced branch road in FFT result, and delayed branch road is sent out
2 sentnIndividual accumulated value carries out 2nThe FFT of point, obtains the maximum of delayed branch road in FFT result, the instant branch road
Transmission 2nIndividual accumulated value is to remove the information code after pseudo-code；
Step 8, if the maximum of advanced branch road is more than the maximum of delayed branch road in FFT result in FFT result,
FFT judge modules driving tracking pseudo-code phase adjusting module is tracked by the delayed sampled point of real time data update module；
If the maximum of advanced branch road is less than the maximum of delayed branch road in FFT result in FFT result, track
FFT judge modules driving tracking pseudo-code phase adjusting module is by the super previous sampled point of real time data update module, to hits
Pseudo-code in is tracked.
4. the acquiring pseudo code and tracking of a kind of spread-spectrum signal according to claim 3, it is characterised in that in step 4,
Repeat step 2 and step 3 totally 2 × (2n- 1) during secondary,
Taking-up 2 correlator the 1st time is captured at the address 0 in data cache modulen× M sampled datas, capture correlator the
2 times at the address M/2 in data cache module taking-up 2n× M sampled datas, until capture correlator the 2nd × (2n-1)
The secondary address [2 × (2 from data cache modulen- 1) 2 are taken out at -1] × M/2n× M sampled datas.
5. the acquiring pseudo code and tracking of a kind of spread-spectrum signal according to claim 4, it is characterised in that in step 4,
The phase offset between local pseudo-code sequence and input spread-spectrum signal is obtained, is specially：
If the global maximum is 2 × (2n- 1) l-th in individual maximum, then local pseudo-code sequence is with inputting spread-spectrum signal
Between phase offset be (L-1) × M/2.
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