CN107317600B - 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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- CN107317600B CN107317600B CN201710419267.8A CN201710419267A CN107317600B CN 107317600 B CN107317600 B CN 107317600B CN 201710419267 A CN201710419267 A CN 201710419267A CN 107317600 B CN107317600 B CN 107317600B
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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
-
- 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
Abstract
The invention belongs to spread spectrum technic fields, disclose the acquiring pseudo code and tracking system and method for a kind of spread-spectrum signal, comprising: data cache module, capture correlator, capture FFT judgment module, real time data update module, tracking correlator, tracking FFT judgment module, capture pseudo-code phase adjustment module, capture pseudo-code generation module, tracking pseudo-code phase adjustment module and tracking pseudo-code generation module；Because the information code of transmitting terminal is one-to-one with pseudo-code, in receiving end, pseudo-code phase is consistent with the pseudo-code phase that transmitting terminal is modulated, and during acquiring pseudo code and tracking, receiving end pseudo-code phase remains unchanged, it is bigger than the value that the catching method of traditional mobile pseudo-code obtains by integrating cumulative obtained value after PN synchronization in receiving end pseudo-code and input spread-spectrum signal；The ability for improving acquiring pseudo code and tracking, the demodulation after being also beneficial to despreading, and then reception system is improved to the detecting and tracking ability of 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, the acquiring pseudo code of the Direct Sequence Spread Spectrum Signal suitable for spread spectrum communication and tracking.
Background technique
Communication environment it is complicated and changeable, it is anti-interference, in terms of more stringent requirements are proposed, spread spectrum communication skill
Art these two aspects advantage so that being applied widely in mobile communication field and satellite communication field.In spread spectrum communication
In system, spread-spectrum signal track receiver is one of important branch, has reacted expansion to the ability of spread-spectrum signal detection
The development of the frequency communication technology.In band spread receiver, needs to be de-spread with pseudo-code identical with transmitting terminal, eliminate the shadow of pseudo-code
It rings, extracts raw information code signal；Since the bandwidth of spread-spectrum signal is very big, power spectral density very little, so in anti-interference and letter
Breath secrecy aspect has outstanding advantages.
Method for acquiring pseudo code has serial acquisition, parallel capture, matched filtering etc. several.
The realization of serial acquisition method are as follows: the data of a related cumulative PN-code capture every time, related accumulated result with
Thresholding comparison is greater than thresholding then acquisition success, otherwise continues the phase of mobile half pseudo- code length of pseudo-code related cumulative.But
Capture time is longer, and the time is not fixed, when a pseudo-code (PN-code capture is how many then comprising how many a pseudo-codes) sampling one
When point, the time is very fast, but increasing with pseudo-code sampling number, and related accumulation length is multiplied, capture time at
Increase again.
The realization of parallel acquiring pseudo code are as follows: if PN-code capture is N, need first to store the pseudo-code that the 2N group period is N, often
The phase of half of pseudo- code length is differed between two adjacent groups.Input signal is related to this 2N group pseudo-code simultaneously cumulative, and consumption is a large amount of
Resource, if PN-code capture is shorter (such as PN-code capture 31), it is less to consume resource, too long (such as the PN-code capture of pseudo-code
1023) resource then can largely be occupied.
Matched filtering catching method is realized are as follows: as FIR filter structure, coefficient is pseudo-code, although capture time
Comparatively fast, consumption resource is less, but with the variation of a pseudo-code sampling number, its adaptability is very poor.
Above several existing methods have the shortcomings that one it is common, that is, not can guarantee related cumulative energy must be maximum
, when information code jump ,+1 becomes -1, if related cumulative length just includes half+1, half -1, then related add up is tied
Fruit is 0, and energy is minimum.
Summary of the invention
The shortcomings that for the above-mentioned prior art, the purpose of the present invention is to provide a kind of acquiring pseudo code of spread-spectrum signal with
Track system and method can be improved capture and the tracking performance of pseudo-code.
In order to achieve the above objectives, the present invention is realised by adopting the following technical scheme.
Technical solution one:
A kind of acquiring pseudo code and tracking system of spread-spectrum signal, the system comprises: data cache module, capture are related
Device, capture FFT judgment module, real time data update module, tracking correlator, tracking FFT judgment module, capture pseudo-code phase tune
Mould preparation block, capture pseudo-code generation module, tracking pseudo-code phase adjustment module and tracking pseudo-code generation module；
Wherein, it is provided with signal input part, feedback signal input terminal and signal output end in the data cache module,
Signal input part, preset signal input terminal and signal output end are provided on the capture correlator, the capture pseudo-code produces
It is provided with preset signal output end in raw module, is provided with signal input part, signal output end on the capture FFT judgment module
And feedback signal output, feedback signal input terminal is provided in capture pseudo-code phase adjustment module and feedback signal is defeated
Outlet；
It is defeated that the first signal input part, second signal input terminal, feedback signal are provided in the real time data update module
Enter end and signal output end, it is defeated to be provided with signal input part, preset signal input terminal and signal on the tracking correlator
Outlet is provided with preset signal output end on the tracking pseudo-code generation module, is provided with letter on the tracking FFT judgment module
Number input terminal and feedback signal output are provided with feedback signal input terminal and feedback in the tracking pseudo-code phase adjustment module
Signal output end.
The characteristics of technical solution of the present invention one and further improvement are as follows:
The signal input part of the data cache module is for inputting spread-spectrum signal；The signal of the data cache module is defeated
Outlet is connect with the signal input part of capture correlator, captures the signal output end of correlator and the letter of capture FFT judgment module
The connection of number input terminal captures the feedback signal output of FFT judgment module and the feedback signal of capture pseudo-code phase adjustment module
Input terminal connection, the feedback signal output of capture pseudo-code phase adjustment 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 connect with the preset signal input terminal of capture correlator；
First signal input part of the real time data update module is for inputting spread-spectrum signal；Real time data update module
Second signal input terminal connect with the signal output end of capture FFT judgment module, the signal of real time data update module exports
It holds and is connect with the signal input part of tracking correlator, track the signal output end of correlator and the signal of tracking FFT judgment module
Input terminal connection, the feedback signal output for tracking FFT judgment module and the feedback signal of tracking pseudo-code phase adjustment module are defeated
Enter end connection, the feedback signal output of tracking pseudo-code phase adjustment module and the feedback signal of real time data update module input
End connection；The preset signal output end of the tracking pseudo-code generation module is connect with the preset signal input terminal of tracking correlator.
Technical solution two:
A kind of acquiring pseudo code and tracking of spread-spectrum signal, the spread-spectrum signal refer in information code after modulation pseudo-code
Signal, and the pseudo-code be period code, generated by shift register, if number of shift register stages be n, then modulate a cycle
It include 2 in the spread-spectrum signal of pseudo-coden- 1 pseudo-code carries out the sampling of M point to each pseudo-code, then from modulation a cycle pseudo-code
Sampling obtains (2 in spread-spectrum signaln- 1) × M sampled data；Described method includes following steps:
Step 1, the sampled data of two PN-code captures is cached in data cache module, is total to (2n- 1) × M × 2 hits
According to the sampled data of described two PN-code captures is the data 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 are M, by the M sampled data and
A data in local pseudo code sequence are multiplied to obtain M multiplied result data, then the M multiplied result data accumulation that will be obtained
Obtain an accumulation result data；To obtain 2nA accumulation result data, and by described 2nA accumulation result data, which are sent to, catches
Obtain FFT judgment module；
Step 3, capture FFT judgment module is to described 2nA accumulation result data carry out 2nThe FFT transform of point obtains FFT change
It changes as a result, and obtaining the maximum value in FFT transform result；
Capture FFT judgment module driving capture pseudo-code phase and adjust 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) secondary, to obtain 2 in capture FFT judgment module
×(2n- 1) a maximum value；
Determine described 2 × (2n- 1) mean value of a maximum value, and by described 2 × (2n- 1) mean value of a maximum value is denoted as entirely
Office's average value；And determine described 2 × (2n- 1) maximum value in a maximum value, and by described 2 × (2n- 1) in a maximum value most
Big value is denoted as global maximum；
If the global maximum is greater than P times of global mean value, P is the integer greater than 1, it is determined that realizes pseudo-code and catches
It obtains, to obtain local pseudo code sequence and input the phase offset between spread-spectrum signal, enters step 5 carry out pseudo-code tracings；
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 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 lag code, i.e. half of advanced code pseudo- code length of the time-code lag, the lag code lag are instant
Half of code pseudo- code length；
Three branches, respectively advanced branch, instant branch and lag branch are provided in the tracking correlator；It is described
Advanced branch is used to carry out the relevant 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 are used to carry out the related behaviour that correlation length is M to the i.e. time-code to M sampled data
Make, obtain the accumulated value of an instant branch, the lag branch is used to carry out correlation length to M sampled data and lag code
For the relevant operation of M, the accumulated value of a lag branch is obtained, and the accumulated value of each branch is sent to tracking FFT judgement
Module；
Step 7, when the tracking FFT judgment module obtains 2 that three branches are sent respectivelynAfter a accumulated value, to advanced
The 2 of branch transmissionnA accumulated value carries out 2nThe FFT transform of point, obtains the maximum value of advanced branch in FFT transform result, to lag
The 2 of branch transmissionnA accumulated value carries out 2nThe FFT transform of point obtains the maximum value that branch is lagged in FFT transform result, described to be
The 2 of Shi Zhilu transmissionnA accumulated value is the information code after removing pseudo-code, as last output；
Step 8, if the maximum value of advanced branch is greater than the maximum for lagging branch in FFT transform result in FFT transform result
Value then tracks FFT judgment module driving tracking pseudo-code phase adjustment module for the stagnant the latter sampled point of real time data update module；
If the maximum value of advanced branch is less than the maximum value for lagging branch in FFT transform result in FFT transform result, with
Track FFT judgment module driving tracking pseudo-code phase adjustment 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 improvement are as follows:
(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 from the address 0 in data cache modulen× M sampled data captures phase
Taking-up 2 device the 2nd time is closed from the address M/2 in data cache modulen× M sampled data, 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 data.
(2) it in step 4, obtains local pseudo code sequence and inputs the phase offset between spread-spectrum signal, specifically:
If the global maximum is 2 × (2n- 1) l-th in a maximum value, then local pseudo code sequence and input are spread
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 thus can be shortened the acquiring pseudo code time.By
It is remained unchanged in the pseudo-code phase of this research implementation method, after local pseudo-code is synchronous with input spread-spectrum signal, FFT processing is
The continuous complete PN-code capture data of one pseudo-code phase further increase acquiring pseudo code so accumulation energy reaches maximum
Ability.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
It obtains other drawings based on these drawings.
Fig. 1 is the realization block diagram of acquiring pseudo code of the invention and tracking.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
Pseudo-code is generated by shift register, it is assumed that register series is n, then the pseudo- code length (period) generated is
2n- 1 (i.e. PN-code capture includes 2n- 1 pseudo-code), it is assumed that a pseudo-code samples M point and (is determined by sample rate and pseudo- bit rate
It is fixed), then a PN-code capture sampling (2n- 1) × M data.Because FFT treated length generally is 2n, so according to pseudo-code week
Phase, for the selection of FFT treated length one more than PN-code capture, i.e. the length of FFT processing is selected as 2 in the embodiment of the present inventionn, the puppet
The method of Code acquisition and tracking, comprising the following steps:
Step 1, data cache module caches the sampled data of two PN-code captures, according to the above analysis, FFT treated length
It is 2n, so taking out 2 from data cache module every timen× M sampled data and the pseudo-code that capture pseudo-code generation module generates 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
It is 2nSection, every segment length are M, are first multiplied with a sampled point of local pseudo-code to every M sampled data, then this M is sampled
Data accumulation, capture correlator output 2nA processing result send capture FFT judgment module, and capture FFT judgment module carries out 2nPoint
FFT processing, and record this maximum value；
Capture FFT judgment module drives capture pseudo-code phase adjustment 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 2 are taken out from data cache module againn× M hits
According to, send capture correlator, capture FFT judgment module etc. to be handled, and record secondary FFT result maximum value, repeat with
Upper step carries out 2 × (2 altogethern- 1) secondary, it fetches since the address of data cache module 0, is opened for the second time from address M/2 for the first time
Beginning access ..., the 2nd × (2n- 1) secondary from address [2 × (2n- 1) -1] × M/2 access.2 are taken out every timen× M hits
According to.Obtain 2 × (2n- 1) a FFT result maximum value again capture FFT judgment module find this 2 × (2n- 1) maximum of a result
Value and mean value.And by maximum value compared with mean value, when maximum value is greater than P (integer greater than 1) times mean value, that is, think to realize
Acquiring pseudo code obtains local pseudo-code and inputs the phase offset between spread-spectrum signal into pseudo-code tracing process, and 2 × (2n-1)
In a value, which time FFT result is maximum value 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 L time FFT result is maximum, then local pseudo-code with input spread-spectrum signal it
Between phase offset be just (L-1) × M/2, access address be also (L-1) × M/2.Step is executed 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 and input spread-spectrum signal that real time data update module is obtained according to acquiring pseudo code part it
Between phase offset, adjust real time data phase to reach acquiring pseudo code purpose, implement as according to the sampling of phase offset
Points wait for tracking pseudo-code generation module in several clock cycle and do not export pseudo-code, then export from tracking pseudo-code generation module
Pseudo-code.
It tracks pseudo-code generation module and generates advanced, instant, three tunnel pseudo-codes of lag, be referred to as advanced code, i.e. time-code, lag
Code, what is directly exported is just advanced code, i.e., time-code lags half of pseudo-code phase of advanced code, and lag code lag is half of pseudo-code of time-code
Phase, three tunnel pseudo-codes respectively to input spread-spectrum signal tracking correlator in related, be referred to as advanced branch, instant branch,
Branch is lagged, correlation length is a pseudo- code length, i.e. M；Every M sampled data is first multiplied with pseudo-code in tracking correlator,
It adds up again, output enters tracking FFT judgment module, when obtaining 2nA accumulated value, in tracking FFT judgment module, advanced branch,
Lag branch carries out 2 respectivelynPoint FFT processing obtains FFT result and the advanced branch of comparison, lag branch FFT result maximum value,
Drive tracking pseudo-code phase adjustment module by the stagnant the latter sampled point of real time data update module if being greater than lag in advance；Such as
Fruit is less than lag in advance and then drives tracking pseudo-code phase adjustment module by the super previous sampled point of real time data update module；The mistake
Cheng Yizhi is adjusted in dynamic.The output of branch immediately is exactly the signal after removing pseudo-code in tracking correlator.
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 thus can be shortened the acquiring pseudo code time.By
In implementation method of the embodiment of the present invention, pseudo-code phase is remained unchanged, 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 increased
The ability of acquiring pseudo code.
Illustratively, if sample rate 60MHz, pseudo- bit rate 5MHz, PN-code capture 1023, a pseudo-code samples at 12 points.Ginseng
It is the realization block diagram of acquiring pseudo code of the invention and tracking according to Fig. 1；The implementation method of the acquiring pseudo code and tracking, comprising: number
According to cache module, capture pseudo-code generation module, capture pseudo-code phase adjustment module, capture FFT judgment module, capture correlator,
Correlator, tracking pseudo-code generation module, tracking pseudo-code phase adjustment module, tracking FFT judgment module, real time data is tracked to update
Module；The acquiring pseudo code and tracking, comprising the following steps:
Step 1, acquiring pseudo code is carried out first, carries out pseudo-code tracing after acquiring pseudo code success.Data cache module caching two
The sampled data of a PN-code capture, according to the above analysis, FFT treated length is 1024, so taking every time from data cache module
1024*12 sampled data enters capture related, the phase of correlator progress to the pseudo-code that capture pseudo-code generation module generates jointly out
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, is first multiplied, then this 12 sampled datas are added up, catches with a sampled point of pseudo-code to every 12 sampled datas
It obtains 1024 processing results of correlator output and send capture FFT judgment module, capture FFT judgment module carries out at 1024 points of FFT
Reason, and record this maximum value；
Capture FFT judgment module drives capture pseudo-code phase adjustment module to make the sampling number in data cache module simultaneously
1024*12 sampling is taken out from data cache module according to the sampled data (i.e. 6) for half of the pseudo- code length that moves right, and again
Data send capture correlator, capture FFT judgment module etc. to be handled, and record secondary FFT result maximum value, repeat
Upper step 2046 time is fetched since the address of data cache module 0 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 maximum values again
The maximum value and mean value of this 2046 results are found in capture FFT judgment module.And by maximum value compared with mean value, work as maximum value
When greater than 8 times of mean values, that is, think to realize acquiring pseudo code, into pseudo-code tracing process, obtains local pseudo-code and input spread spectrum letter
Phase offset between number, acquiring pseudo code successful execution step 2；Otherwise it empties data cache module and caches 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), expression formula are as follows:
Wherein, A is signal amplitude, and ω is angular speed,For difference, t indicates 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 pseudo-code c ' (t) of duplication and c (t) are complete
It is consistent then pseudo-code c (t) can be eliminated, achieve the purpose that despreading.Capture makes c ' (t) to differ most half pseudo- code length phases with c (t)
Position, tracking keep c ' (t) almost the same with c (t).
Step 2, the local pseudo-code and input spread-spectrum signal that real time data update module is obtained according to acquiring pseudo code part it
Between phase offset, adjust real time data phase to reach acquiring pseudo code purpose, implement as according to the sampling of phase offset
Points wait for several clock cycle, then export pseudo-code from tracking pseudo-code generation module.
It tracks pseudo-code generation module and generates advanced, instant, three tunnel pseudo-codes of lag, be referred to as advanced code, i.e. time-code, lag
Code, what is directly exported is just advanced code, i.e., time-code lags half of pseudo-code phase of advanced code, and lag code lag is half of pseudo-code of time-code
Phase, three tunnel pseudo-codes respectively to input spread-spectrum signal tracking correlator in related, be referred to as advanced branch, instant branch,
Lagging branch, correlation length is a 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 judgment module, when obtaining 1024 accumulated values, in tracking FFT judgment module, in advance
Branch, lag branch carry out 1024 point FFT processing respectively, obtain FFT result and the advanced branch of comparison, lag branch FFT result
Maximum value drives tracking pseudo-code phase adjustment module to adopt the stagnant the latter of real time data update module if being greater than lag in advance
Sampling point；Drive tracking pseudo-code phase adjustment module by the super previous sampling of real time data update module if being less than lag in advance
Point；The process is adjusted in dynamic always.The output of branch immediately is exactly the signal after removing pseudo-code in tracking correlator.
Step 3, whether acquiring pseudo code succeeds with tracking, and the dynamically track of pseudo-code is kept if success；Otherwise, step is returned
Rapid 1, above-mentioned steps are recycled, until the PN synchronization in local pseudo-code and input Direct Sequence Spread Spectrum Signal.
Because the information code of transmitting terminal and pseudo-code are that correspondingly, in receiving end, pseudo-code phase is modulated with transmitting terminal
Pseudo-code phase is consistent, and during acquiring pseudo code and tracking, receiving end pseudo-code phase is remained unchanged, so finally working as
After PN synchronization in receiving end pseudo-code and input spread-spectrum signal, all compare under normal circumstances by integrating cumulative obtained value
The catching method of traditional mobile pseudo-code is big.The ability of acquiring pseudo code and tracking is not only increased, while being more favorable to de-spread
Demodulation afterwards, and then reception system is improved to the detecting and tracking ability of spread-spectrum signal.
Those of ordinary skill in the art will appreciate that: realize that all or part of the steps of above method embodiment can pass through
The relevant hardware of program instruction is completed, and program above-mentioned can store in computer-readable storage medium, which exists
When execution, step including the steps of the foregoing method embodiments is executed；And storage medium above-mentioned includes: ROM, RAM, magnetic or disk
Etc. the various media that can store program code.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
Those familiar with the art in the technical scope disclosed by the present invention, can easily think of the change or the replacement, and should all contain
Lid is 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 (4)
1. the acquiring pseudo code and tracking system of a kind of spread-spectrum signal, which is characterized in that the system comprises: data cache module,
Capture correlator, capture FFT judgment module, real time data update module, tracking correlator, tracking FFT judgment module, capture puppet
Code phase adjusts module, capture pseudo-code generation module, tracking pseudo-code phase adjustment module and tracking pseudo-code generation module；
Wherein, signal input part, feedback signal input terminal and signal output end are provided in the data cache module, it is described
Signal input part, preset signal input terminal and signal output end are provided on capture correlator, the capture pseudo-code generates mould
Preset signal output end is provided on block, be provided on the capture FFT judgment module signal input part, signal output end and
Feedback signal output, the capture pseudo-code phase, which adjusts, is provided with feedback signal input terminal and feedback signal output in module
End；
The first signal input part, second signal input terminal, feedback signal input terminal are provided in the real time data update module
And signal output end, signal input part, preset signal input terminal and signal output end are provided on the tracking correlator,
Preset signal output end is provided on the tracking pseudo-code generation module, it is defeated to be provided with signal on the tracking FFT judgment module
Enter end and feedback signal output, is provided with feedback signal input terminal and feedback signal in the tracking pseudo-code phase adjustment module
Output end；
The signal input part of the data cache module is for inputting spread-spectrum signal；The signal output end of the data cache module
It is connect with the signal input part of capture correlator, the signal for capturing the signal output end and capture FFT judgment module of correlator is defeated
Enter end connection, the feedback signal of the feedback signal output and capture pseudo-code phase adjustment module that capture FFT judgment module inputs
End connection, the feedback signal output of capture pseudo-code phase adjustment module and the feedback signal input terminal of data cache module connect
It connects；The preset signal output end of the capture pseudo-code generation module is connect with the preset signal input terminal of capture correlator；
First signal input part of the real time data update module is for inputting spread-spectrum signal；The of real time data update module
Binary signal input terminal with capture FFT judgment module signal output end connect, the signal output end of real time data update module and
The signal of the signal input part connection for tracking correlator, the signal output end and tracking FFT judgment module that track correlator inputs
End connection tracks the feedback signal output of FFT judgment module and the feedback signal input terminal of tracking pseudo-code phase adjustment module
Connection, the feedback signal output of tracking pseudo-code phase adjustment module and the feedback signal input terminal of real time data update module connect
It connects；The preset signal output end of the tracking pseudo-code generation module is connect with the preset signal input terminal of tracking correlator.
2. the acquiring pseudo code and tracking of a kind of spread-spectrum signal, which is characterized in that the spread-spectrum signal refers in information code
Signal after modulating pseudo-code, 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 carries out the sampling of M point to each pseudo-code, then sampling obtains (2 from the spread-spectrum signal of one PN-code capture of modulationn-1)×
M sampled data；Described method includes following steps:
Step 1, the sampled data of two PN-code captures is cached in data cache module, is total to (2n- 1) × M × 2 sampled data, institute
The sampled data for stating two PN-code captures is the data 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 local
A data in pseudo-code sequence are multiplied to obtain M multiplied result data, then M obtained multiplied result data accumulation is obtained
One accumulation result data；To obtain 2nA accumulation result data, and by described 2nA accumulation result data are sent to capture
FFT judgment module；
Step 3, capture FFT judgment module is to described 2nA accumulation result data carry out 2nThe FFT transform of point, obtains FFT transform knot
Fruit, and obtain the maximum value in FFT transform result；
It captures FFT judgment module driving capture pseudo-code phase and adjusts module, the sampled data in data cache module is made to move 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) secondary, to obtain 2 × (2 in capture FFT judgment modulen-
1) a maximum value；
Determine described 2 × (2n- 1) mean value of a maximum value, and by described 2 × (2n- 1) mean value of a maximum value is denoted as global flat
Mean value；And determine described 2 × (2n- 1) maximum value in a maximum value, and by described 2 × (2n- 1) maximum value in a maximum value
It is denoted as global maximum；
If the global maximum is greater than P times of global mean value, P is the integer greater than 1, it is determined that acquiring pseudo code is realized,
To obtain local pseudo code sequence and input the phase offset between spread-spectrum signal, 5 carry out pseudo-code tracings are entered step；
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 step 2；
Step 5, real time data update module is obtained according to the phase offset between local pseudo code sequence and input spread-spectrum signal, adjustment
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, three tunnel pseudo-code from the tracking pseudo-code generation module respectively include:
Advanced code, i.e. time-code and lag code, i.e. half of advanced code pseudo- code length of the time-code lag, the lag code lag is time-code half
A puppet code length；
Three branches, respectively advanced branch, instant branch and lag branch are provided in the tracking correlator；It is described advanced
Branch is used to carry out the relevant operation that correlation length is M to M sampled data and the advanced code, obtains an advanced branch
Accumulated value, the instant branch are used to carry out the relevant operation that correlation length is M to M sampled data and the i.e. time-code, obtain
To the accumulated value of an instant branch, the lag branch is used to carry out correlation length to M sampled data and lag code to be M's
Relevant operation obtains the accumulated value of a lag branch, and the accumulated value of each branch is sent to tracking FFT judgment module；
Step 7, when the tracking FFT judgment module obtains 2 that three branches are sent respectivelynAfter a accumulated value, advanced branch is sent out
2 sentnA accumulated value carries out 2nThe FFT transform of point, obtains the maximum value of advanced branch in FFT transform result, to lag branch hair
2 sentnA accumulated value carries out 2nThe FFT transform of point obtains the maximum value that branch is lagged in FFT transform result, the instant branch
Transmission 2nA accumulated value is the information code after removing pseudo-code；
Step 8, if the maximum value of advanced branch is greater than the maximum value for lagging branch in FFT transform result in FFT transform result,
FFT judgment module driving tracking pseudo-code phase adjustment module is tracked by the stagnant the latter sampled point of real time data update module；
If the maximum value of advanced branch is less than the maximum value for lagging branch in FFT transform result in FFT transform result, track
FFT judgment module driving tracking pseudo-code phase adjustment module is by the super previous sampled point of real time data update module, to hits
Pseudo-code in is tracked.
3. the acquiring pseudo code and tracking of a kind of spread-spectrum signal according to claim 2, which is characterized 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 from the address 0 in data cache modulen× M sampled data, capture correlator the
2 times from the address M/2 in data cache module taking-up 2n× M sampled data, until capturing 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 data.
4. the acquiring pseudo code and tracking of a kind of spread-spectrum signal according to claim 3, which is characterized in that in step 4,
It obtains local pseudo code sequence and inputs the phase offset between spread-spectrum signal, specifically:
If the global maximum is 2 × (2n- 1) l-th in a maximum value, then local pseudo code sequence and input spread-spectrum signal
Between phase offset be (L-1) × M/2.
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