CN110071738A - Spread-spectrum signal based on more pseudo-code branch receivers de-spreads tracking - Google Patents
Spread-spectrum signal based on more pseudo-code branch receivers de-spreads tracking Download PDFInfo
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- CN110071738A CN110071738A CN201910349177.5A CN201910349177A CN110071738A CN 110071738 A CN110071738 A CN 110071738A CN 201910349177 A CN201910349177 A CN 201910349177A CN 110071738 A CN110071738 A CN 110071738A
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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
- H04B1/7073—Synchronisation aspects
- H04B1/7085—Synchronisation aspects using a code tracking loop, e.g. a delay-locked loop
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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
- H04B1/7087—Carrier synchronisation aspects
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Abstract
The invention discloses a kind of, and the spread-spectrum signal based on more pseudo-code branch receivers de-spreads tracking.Method includes the following steps: the reception of spread-spectrum signal and digital down-converted；Establish lag pseudo-code branch, instant pseudo-code branch, advanced pseudo-code branch；The capture and tracking of pseudo-code are carried out by three pseudo-code branches；The capture and tracking of high-frequency offset carrier are carried out by instant branch.The present invention is arranged by multiple branch circuit and the acquiring pseudo code based on Fast Fourier Transform (FFT) processing tracks, and can be realized the quick detection of the smallest branch of pseudo-code phase difference, and according to the mobile pseudo-code of FFT processing result, realizes the fast Acquisition to pseudo-code and tracking；Meanwhile the FFT processing of capturing carrier module, quickly detection can be realized to high-frequency offset carrier, improved the ability of capturing carrier, accelerated acquisition speed.
Description
Technical field
The invention belongs to technical field of satellite communication, in particular to a kind of spread-spectrum signal based on more pseudo-code branch receivers
De-spread tracking, the reception detection and tracking of the satellite-signal suitable for complex environment.
Background technique
With the development of science and technology, spread spectrum technic with its confidentiality high, anti-interference be widely applied to well it is military and
In civil field.In satellite communication field, digital tracking receiver is a critically important branch, is mainly used for satellite antenna
Tracking, demodulate azimuth and pitch angle information, realize accurate tracking of the antenna to satellite.
But the confidentiality of conventional digital track receiver is low, anti-interference is poor, prevent traditional modulated signal is from very
Good transmitting information.In order to solve the above-mentioned drawback of conventional digital track receiver, the track receiver based on spread-spectrum signal is answered
It transports and gives birth to, main thought is to carry out spread processing in signal transmitting terminal to angle signal, realize the video stretching of signal, drop
The signal-to-noise ratio of low signal realizes the safe transmission of signal.When satellite antenna receives the spread-spectrum signal with angle information, receive
Machine is de-spread firstly the need of to signal, is demodulated again later, and accurate azimuth and pitch angle information could be obtained, and is realized
Accurate tracking of the antenna to satellite.
Spread-spectrum signal is to be modulated by pseudo noise code to classical signal, and frequency spectrum is broadened on frequency domain, reaches anti-interference, is protected
Close purpose.Existing Spectrum Spread Tracking receiver is first to de-spread to the signal received, obtains original signal, then to signal
Demodulation process is carried out, azimuth and pitch angle information are finally obtained.And existing despreading method has serial acquisition, parallel capture,
Its core concept is all that local pseudo-code is related to spread-spectrum signal progress cumulative.The shortcomings that this method is not can guarantee correlation to tire out
The energy added is maximum, is also possible that the case where being accumulated as 0 when correlation is cumulative, leads to not accurately obtain pseudo-code phase adjustment
Information, and then the quick despreading and accurate tracking of spread-spectrum signal can not be carried out.
Summary of the invention
To solve the above-mentioned problems, the purpose of the present invention is to propose to a kind of spread-spectrum signals based on more pseudo-code branch receivers
De-spread tracking.The present invention is arranged by multiple branch circuit and is based on Fast Fourier Transform (FFT) (Fast Fourier
Transformation, FFT) processing acquiring pseudo code tracking, can be realized the quick detection of the smallest branch of pseudo-code phase difference,
And according to the mobile pseudo-code of FFT processing result, the fast Acquisition to pseudo-code and tracking are realized；Meanwhile at the FFT of capturing carrier module
Reason can realize quickly detection to high-frequency offset carrier, improve the ability of capturing carrier, accelerate acquisition speed.
In order to achieve the above object, the present invention is resolved using following technical scheme.
Spread-spectrum signal based on more pseudo-code branch receivers de-spreads tracking, comprising the following steps:
Step 1, receiver receives spread-spectrum signal, and carries out Digital Down Convert processing to the spread-spectrum signal, is unloaded
The spread-spectrum signal of wave；
Further, the spread-spectrum signal is by pseudo noise code and the modulated spread-spectrum signal of high frequency carrier.
Further, the Digital Down Convert processing are as follows:
Local digital controlled oscillator generates clean carrier signal, the spread-spectrum signal respectively in clean carrier signal the road I,
The road Q signal is successively multiplied, has limit for length's unit impulse response (Finite Impulse Response, FIR) low-pass filtering,
Obtain the spread-spectrum signal of carrier wave.
Step 2, local pseudo-code is generated by local pn code generator, by carrying out delay process to local pseudo-code, obtained
Pseudo-code branch, instant pseudo-code branch and advanced pseudo-code branch are lagged, will be late by pseudo-code branch, instant pseudo-code branch and advanced pseudo-code
Branch respectively with remove the spread-spectrum signal of carrier wave to be successively multiplied, integrate cumulative, the corresponding lag acquiring pseudo code signal, immediately of obtaining
Acquiring pseudo code signal and advanced acquiring pseudo code signal.
Further, the delay process are as follows: using local pseudo-code as lag pseudo-code branch；It will be late by pseudo-code finger delays
Half of symbol is as instant pseudo-code branch；Instant half of symbol of pseudo-code finger delays is obtained into advanced pseudo-code branch.
Further, the local pn code generator is generated by shift register, and the series of the shift register is
N, the PN-code capture of generation are 2n-1；The sampling number of one pseudo-code is M, then the pseudo-code sampling number of a PN-code capture is
(2n-1)×M。
Further, the cumulative points of the integral are equal to the sampling number M an of pseudo-code, and half of symbol is equal to M/2
Sampled point.
Step 3, lag acquiring pseudo code signal, instant acquiring pseudo code signal and advanced acquiring pseudo code signal are answered respectively
Number FFT processing, judge pseudo-code whether acquisition success: if acquiring pseudo code is unsuccessful, mobile half of the symbol of local pseudo-code is laid equal stress on
Multiple step 2；If acquiring pseudo code success, carries out step 4.
Further, it is described judge pseudo-code whether acquisition success specifically:
The maximum value and average value for calculating the plural number FFT treated acquiring pseudo code signal immediately, by L times be averaged
It is worth the threshold value as acquiring pseudo code, if maximum value is greater than threshold value, acquiring pseudo code success, otherwise, acquiring pseudo code is unsuccessful,
Wherein, 4≤L≤16.
Further, the points of the plural number FFT processing are 2n。
Step 4, acquiring pseudo code success after, using plural FFT treated lag acquiring pseudo code signal and plural number FFT processing
Advanced acquiring pseudo code signal afterwards carries out pseudo-code tracing；Meanwhile carrier wave is carried out using instant acquiring pseudo code signal and is caught.
Further, it is described using plural number FFT treated lag acquiring pseudo code signal and plural number FFT treated in advance
Acquiring pseudo code signal carries out pseudo-code tracing, the specific steps are that:
Compare plural FFT treated the maximum value and plural number FFT treated advanced pseudo-code of lag acquiring pseudo code signal
Capture the maximum value of signal: if treated less than plural number FFT for the maximum value of plural number FFT treated lag acquiring pseudo code signal
The maximum value of advanced acquiring pseudo code signal, then local pseudo-code moves 1 sampled point to advanced direction；If treated by plural number FFT
The maximum value for lagging acquiring pseudo code signal is greater than plural number FFT treated the maximum value of advanced acquiring pseudo code signal, then local puppet
Code moves 1 sampled point to lag direction；If plural number FFT treated lag acquiring pseudo code signal maximum value be equal to plural number
The maximum value of FFT treated advanced acquiring pseudo code signal, then pseudo-code tracing success, i.e. spread-spectrum signal despreading are completed.
Further, described that capturing carrier is carried out using instant acquiring pseudo code signal, the specific steps are that:
Firstly, real number FFT traction is carried out again after being multiplied using the road I in instant acquiring pseudo code signal with the road Q signal,
Obtain capturing carrier FFT signal.
Secondly, the corresponding frequency of maximum value position of capturing carrier FFT signal, as FFT lock are obtained, and then
To the corresponding frequency control word of FFT lock, as lock control word.
Finally, the fixed frequency control word of receiver is added with the lock control word, using frequency after being added
Rate control word controls local digital controlled oscillator and generates corresponding traction carrier wave；Calculate the frequency between traction carrier wave and spread-spectrum signal
Difference, if the resolution ratio that real number FFT of the frequency difference more than or equal to K times is drawn, repeats capturing carrier；If frequency difference is less than K times
The resolution ratio of real number FFT traction, then capturing carrier success, obtains capture frequency；Wherein, 1≤K≤2.
Further, real number FFT traction specifically: in instant acquiring pseudo code signal the road I and the road Q signal carry out
The signal obtained after multiplication carries out J point real number FFT traction；It is positive and negative that determination frequency is handled by plural number FFT again, finally, to J point reality
Number FFT traction after signal real and imaginary parts it is squared and, obtain capturing carrier FFT signal.
Further, the resolution ratio of the real number FFT traction are as follows:Wherein, clk is sampling clock, and M is long-pending
Divide cumulative points, J is real number FFT traction points.
Step 5, after acquiring pseudo code success, carrier track is carried out using instant acquiring pseudo code signal.
It is described that carrier track is carried out using instant acquiring pseudo code signal, the specific steps are that:
Firstly, using in instant acquiring pseudo code signal the road I and the road Q signal to carry out integral respectively cumulative and integral is tired
The road I and the road Q signal after adding successively carry out phase identification, loop filtering processing, the signal after obtaining loop filtering, and then obtain
The corresponding frequency control word of signal after loop filtering.
Secondly, by the corresponding frequency control of signal after the fixed frequency control word of receiver, capture frequency and loop filtering
Word processed sums up；The carrier wave that local digital controlled oscillator generates respective frequencies is controlled using the frequency control word after adduction, this is right
After answering the carrier wave of frequency and the spread-spectrum signal to carry out Digital Down Convert processing, successively it is multiplied, is accumulated with instant pseudo-code branch
Divide and add up, obtains I, Q two paths of signals of carrier track, by locking decision condition, judge whether carrier track succeeds.
Further, the locking decision condition are as follows:
To in I, Q two paths of signals of carrier track the road I and the road Q signal carry out square operation respectively, correspondence obtains the road I
Square, it is denoted as I2, square of the road Q signal be denoted as Q2；Locking decision condition is set as I2> 2Q2；Circulation carries out 30 lockings
Judgement then determines carrier track success, otherwise, continues to carry when the judgement number for meeting locking decision condition is greater than 20 times
Wave tracking, until carrier track success.
Compared with prior art, the invention has the benefit that
Acquiring pseudo code of the present invention by multiple pseudo-code branches and based on FFT processing tracks, and it is poor to can be realized pseudo-code phase
The quick detection of the smallest branch, and according to the mobile pseudo-code of FFT processing result, realize the fast Acquisition to pseudo-code and tracking；Together
When, the FFT processing of capturing carrier module can realize quickly detection to high-frequency offset carrier, improve the ability of capturing carrier,
Accelerate acquisition speed.The method of the present invention solves signal in the complex environments such as unstable, strong jamming and de-spreads tracking problem, raising
The despreading speed and accuracy of spread-spectrum signal.
Detailed description of the invention
The present invention is described in further details in the following with reference to the drawings and specific embodiments.
Fig. 1 is the flow diagram of the spread-spectrum signal despreading tracking of the invention based on more pseudo-code branch receivers.
Fig. 2 is the acquiring pseudo code flow diagram in the present invention.
Fig. 3 is the pseudo-code tracing flow diagram in the present invention.
Fig. 4 is capture and the trace flow schematic diagram of the carrier wave in the present invention.
Fig. 5 is the signal graph in the present invention in embodiment when pseudo-code tracing success；Wherein, Fig. 5 (a) is in spread-spectrum signal
Pseudo-code, Fig. 5 (b) are the local pseudo-codes that local pn code generator generates.
Fig. 6 is I, Q two paths of signals figure in the embodiment of the present invention after carrier track success.
Specific embodiment
The embodiment of the present invention and effect are described in further detail with reference to the accompanying drawing.
With reference to Fig. 1, the spread-spectrum signal based on multi-branch receiver de-spreads tracking, comprising the following steps:
Step 1, receiver receives spread-spectrum signal, and carries out Digital Down Convert processing to the spread-spectrum signal, is unloaded
The spread-spectrum signal of wave.
Wherein, the spread-spectrum signal is by pseudo noise code and the modulated spread-spectrum signal of high frequency carrier.Under the number
Frequency-conversion processing are as follows: local digital controlled oscillator generates clean carrier signal, the spread-spectrum signal respectively with the I in clean carrier signal
Road, the road Q signal are successively multiplied, have limit for length's unit impulse response FIR low-pass filtering, and the spread-spectrum signal of carrier wave is obtained.
Step 2, local pseudo-code is generated by local pn code generator, by carrying out delay process to local pseudo-code, obtained
Pseudo-code branch, instant pseudo-code branch and advanced pseudo-code branch are lagged, will be late by pseudo-code branch, instant pseudo-code branch and advanced pseudo-code
Branch respectively with remove the spread-spectrum signal of carrier wave to be successively multiplied, integrate cumulative, the corresponding lag acquiring pseudo code signal, immediately of obtaining
Acquiring pseudo code signal and advanced acquiring pseudo code signal.
Specifically, with reference to Fig. 2, local pn code generator is generated by shift register, and then generate local pseudo-code.It is described
The series of shift register is n, and the PN-code capture of generation is 2n-1；The sampling number of one pseudo-code is M, then a PN-code capture
Pseudo-code sampling number be (2n-1)×M.Using local pseudo-code as lag pseudo-code branch；It will be late by half yard of pseudo-code finger delays
Member is used as instant pseudo-code branch；Instant half of symbol of pseudo-code finger delays is obtained into advanced pseudo-code branch, what the integral added up
Points are equal to the sampling number M an of pseudo-code, and half of symbol is equal to M/2 sampled point.
By instant pseudo-code branch with go the spread-spectrum signal of carrier wave to be successively multiplied, integrate cumulative, obtain instant pseudo-code and catch
Obtain signal；Will be late by pseudo-code branch with go the spread-spectrum signal of carrier wave to be successively multiplied, integrate it is cumulative, obtain lag acquiring pseudo code
Signal；By advanced pseudo-code branch with go the spread-spectrum signal of carrier wave to be successively multiplied, integrate cumulative, obtain advanced acquiring pseudo code letter
Number.
Step 3, lag acquiring pseudo code signal, instant acquiring pseudo code signal and advanced acquiring pseudo code signal are answered respectively
Number FFT processing, it is corresponding obtain plural FFT treated lag acquiring pseudo code signal, plural number FFT treated instant acquiring pseudo code
Signal and plural number FFT treated acquiring pseudo code signal in advance.
It calculates the plural number FFT treated the maximum value and average value of acquiring pseudo code signal immediately, and L times is put down
Threshold value of the mean value as acquiring pseudo code, if maximum value be greater than threshold value, acquiring pseudo code success, otherwise, acquiring pseudo code not at
Function, wherein 4≤L≤16.If acquiring pseudo code is unsuccessful, by mobile half of the symbol of local pseudo-code, and step 2 is repeated；If pseudo-code
Acquisition success then carries out pseudo-code tracing and capturing carrier.Wherein, the points of plural FFT processing are 2n, lag acquiring pseudo code letter
Number, the road I in instant acquiring pseudo code signal and advanced acquiring pseudo code signal this three roads signal as real part, the road Q as imaginary part into
Row plural number FFT processing.
Step 4, acquiring pseudo code success after, using plural FFT treated lag acquiring pseudo code signal and plural number FFT processing
Advanced acquiring pseudo code signal afterwards carries out pseudo-code tracing；Meanwhile capturing carrier is carried out using instant acquiring pseudo code signal.
With reference to Fig. 3, pseudo-code tracing adjusts local pseudo-code phase point by point, until the pseudo-code of local pseudo-code and spread-spectrum signal
It is perfectly aligned.Specific steps are as follows:
Compare plural FFT treated the maximum value and plural number FFT treated advanced pseudo-code of lag acquiring pseudo code signal
Capture the maximum value of signal:
If the maximum value of plural number FFT treated lag acquiring pseudo code signal is less than plural number FFT treated advanced pseudo-code
Capturing the maximum value of signal, then then local pseudo-code continues pseudo-code tracing to mobile 1 sampled point in advanced direction, until
Pseudo-code tracing success.
If the maximum value of plural number FFT treated lag acquiring pseudo code signal is greater than plural number FFT treated advanced pseudo-code
The maximum value of signal is captured, then local pseudo-code moves 1 sampled point to lag direction；Then, continue pseudo-code tracing, until
Pseudo-code tracing success.
If the maximum value of plural number FFT treated lag acquiring pseudo code signal is equal to plural number FFT treated advanced pseudo-code
The maximum value of signal is captured, then pseudo-code tracing success, i.e. spread-spectrum signal despreading is completed.
The adjustment of local pseudo-code phase is to adjust the address control unit in module by local pseudo-code phase to control.On
When stating pseudo-code tracing success, the pseudo-code in local pseudo-code and spread-spectrum signal is alignment, and it is 1 that the two, which is multiplied, that is, realizes spread spectrum
The despreading of signal.
With reference to Fig. 4, the specific steps of capturing carrier are as follows:
Firstly, being multiplied using the road I in instant acquiring pseudo code signal with the road Q signal, multiplication processing is to eliminate
Pseudo-code -1 ,+1 changes the influence to instant tributary signal, carries out real number FFT traction after multiplication processing: being multiplied, treated
Signal is exported to real number FFT traction module, carries out frequency acquisition to big frequency deviation spread-spectrum signal.The points of real number FFT traction are general
It is bigger, consider consume resource and real number FFT traction resolution ratio factor, the present embodiment setting traction points be J point, J according to
The stock number of processing apparatus determines, generally 8132 points or 16384 points.Real number FFT traction resolution ratio beIts
In, clk is sampling clock, and M is the cumulative points of integral, and J is real number FFT traction points.In addition, because real number FFT processing cannot
The positive and negative of signal frequency is judged, so will also be according to 2 in acquiring pseudo code modulenPoint plural number FFT processing is carrying out determination frequency just
It is negative.Finally, to real number FFT traction after signal real and imaginary parts it is squared and, capturing carrier FFT signal is obtained, in this way, just
In the searching to Frequency point position.
Frequency point position is found to capturing carrier FFT signal: since capturing carrier FFT signal is made of J point data, according to
The principle of FFT, Frequency point position will appear maximum value, maximizing position, that is, the Frequency point position detected, by frequency point
Setting and being converted into frequency control word is lock control word；By the fixed frequency control word of receiver and the lock control
Word processed is added, and is controlled local digital controlled oscillator (NCO) using frequency control word after being added and is generated corresponding traction carrier wave；It calculates
The frequency difference between carrier wave and spread-spectrum signal is drawn, if frequency difference is more than or equal to K (1≤K≤2), real number FFT again draws resolution ratio,
Repeat capturing carrier, until capturing carrier success.If frequency difference is less than K (1≤K≤2), real number FFT again draws resolution ratio,
Then capturing carrier success, obtains capture frequency, carrier track starts to start at this time.
Step 5, after capturing carrier success, carrier track is carried out using instant acquiring pseudo code signal.
With reference to Fig. 4, specific steps are as follows:
Firstly, using in instant acquiring pseudo code signal the road I and the road Q signal to carry out integral respectively cumulative, i.e. progress M dot product
Divide cumulative, the instant acquiring pseudo code signal progress 2 of I, Q after integral is cumulativen- 1 accumulation process, and the road I by integral after cumulative
Phase identification, loop filtering processing are successively carried out with the road Q signal, the signal after obtaining loop filtering, and then obtain loop filtering
The corresponding frequency control word of signal afterwards.
Specifically, above-mentioned phase identification realizes that the present embodiment uses arc tangent phase discriminator by carrier wave phase discriminator, by mirror
Phase device obtains the corresponding tangent angle angle value of the instant acquiring pseudo code signal of I, Q after integral adds up, and the angle value is sent to ring
Path filter.
Crucial in digital servo-control ring design to be a little how design loop filter, it is related to the property of entire phaselocked loop
It can superiority and inferiority.Loop filter is for decaying since input signal noise causes fast-changing phase error and smooth phase discriminator to be let out
The high fdrequency component of leakage, accurately to be estimated in its deferent segment original signal.
Secondly, by the corresponding frequency control of signal after the fixed frequency control word of receiver, capture frequency and loop filtering
Word processed sums up；The carrier wave that local digital controlled oscillator generates respective frequencies is controlled using the frequency control word after adduction, this is right
After answering the carrier wave of frequency and the spread-spectrum signal to carry out Digital Down Convert processing, successively it is multiplied, is accumulated with instant pseudo-code branch
Divide and add up, obtains I, Q two paths of signals of carrier track, by locking decision condition, judge whether carrier track succeeds.
In above-mentioned steps, local digital controlled oscillator is by the signal generator of frequency control word control output frequency, in frequency
Under the control of rate control word, sinusoidal signal and cosine signal that the corresponding phase difference for exporting the control word respective frequencies is 90 °.
During carrier track, locking decision starts to start, the specific locking decision condition in above-mentioned steps are as follows:
To in I, Q two paths of signals of carrier track the road I and the road Q signal carry out square operation respectively, correspondence obtains the road I
Square, it is denoted as I2, square of the road Q signal be denoted as Q2；Locking decision condition is set as I2> 2Q2；Circulation carries out 30 lockings
Judgement then determines carrier track success, otherwise, continues to carry when the judgement number for meeting locking decision condition is greater than 20 times
Wave tracking, until carrier track success.
After capturing carrier success, it is believed that do not have between the spread-spectrum signal of carrier wave and input that local digital controlled oscillator generates
Frequency difference, that is, passing through I, Q two-way of Digital Down Convert processing is direct current, wherein the road I signal is non-zero direct current, the road Q signal
It is approximately 0.
Emulation experiment
Effect of the present invention is described further below with reference to Simulink/MATLAB emulation experiment.
(1) simulated conditions
Sample rate being set as 75MHz, the series of pseudo-code shift register is 10, and PN-code capture is 1023, when acquiring pseudo code,
The points of plural FFT processing are 1024, and when capturing carrier, the points of real number FFT traction are 16384, and pseudo- bit rate is 5MHz, often
A symbol sample points are 15.
(2) emulation content
The pseudo-code for setting the received spread-spectrum signal of receiver deviates 8 symbols, and carrier wave frequency deviation is set as 100KHz, uses
Simulink builds the analogue system, realizes the despreading tracking of spread spectrum signal receiver.
(3) analysis of simulation result
Waveform diagram when Fig. 5 is the pseudo-code tracing success of this emulation experiment, from Fig. 5 (a) and Fig. 5 (b) as can be seen that experiment
After, the pseudo-code of the spread-spectrum signal of input and local pseudo-code alignment believe spread spectrum at this point, the two is multiplied to can be realized equal to 1
Number quick despreading；Fig. 6 is the total successful waveform diagram of high-frequency offset carrier Geng of this emulation experiment, from fig. 6, it can be seen that of the invention
Method realizes the accurate tracking lock of high-frequency offset carrier.
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 be stored in a computer readable storage medium, the program
When being executed, step including the steps of the foregoing method embodiments is executed；And storage medium above-mentioned includes: ROM, RAM, magnetic disk or light
The various media that can store program code such as disk.
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 (10)
1. the spread-spectrum signal based on more pseudo-code branch receivers de-spreads tracking, which comprises the following steps:
Step 1, receiver receives spread-spectrum signal, and carries out Digital Down Convert processing to the spread-spectrum signal, obtains carrier wave
Spread-spectrum signal；
Step 2, local pseudo-code is generated by local pn code generator, by carrying out delay process to local pseudo-code, is lagged
Pseudo-code branch, instant pseudo-code branch and advanced pseudo-code branch will be late by pseudo-code branch, instant pseudo-code branch and advanced pseudo-code branch
Respectively with go the spread-spectrum signal of carrier wave to be successively multiplied, integrate it is cumulative, it is corresponding to obtain lag acquiring pseudo code signal, instant pseudo-code
Capture signal and advanced acquiring pseudo code signal；
Step 3, plural number is carried out respectively to lag acquiring pseudo code signal, instant acquiring pseudo code signal and advanced acquiring pseudo code signal
FFT processing, judge pseudo-code whether acquisition success: if acquiring pseudo code is unsuccessful, by mobile half of the symbol of local pseudo-code, and repeat
Step 2；If acquiring pseudo code success, carries out step 4；
Step 4, acquiring pseudo code success after, using plural FFT treated lag acquiring pseudo code signal treated with plural number FFT
Advanced acquiring pseudo code signal carries out pseudo-code tracing；Meanwhile capturing carrier is carried out using instant acquiring pseudo code signal；
Step 5, after acquiring pseudo code success, carrier track is carried out using instant acquiring pseudo code signal.
2. the spread-spectrum signal according to claim 1 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In in step 2, the local pn code generator is generated by shift register, and the series of the shift register is n, is generated
PN-code capture be 2n-1；The sampling number of one pseudo-code is M, then the pseudo-code sampling number of a PN-code capture is (2n-1)×
M；The cumulative points of the integral are equal to the sampling number M an of pseudo-code, and half of symbol is equal to M/2 sampled point.
3. the spread-spectrum signal according to claim 1 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In, in step 2, the delay process are as follows: firstly, using local pseudo-code as lag pseudo-code branch；Secondly, will be late by pseudo-code branch
Postpone half of symbol as instant pseudo-code branch；Finally, instant half of symbol of pseudo-code finger delays is obtained advanced pseudo-code branch.
4. the spread-spectrum signal according to claim 1 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In, in step 3, it is described judge pseudo-code whether acquisition success specifically:
The maximum value and average value for calculating the plural number FFT treated acquiring pseudo code signal immediately, by L times of average value work
For the threshold value of acquiring pseudo code, if maximum value is greater than threshold value, acquiring pseudo code success, otherwise, acquiring pseudo code is unsuccessful；Its
In, 4≤L≤16；The points of the plural number FFT processing are 2n。
5. the spread-spectrum signal according to claim 1 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In, in step 4, it is described using plural number FFT treated lag acquiring pseudo code signal and plural number FFT treated in advance pseudo-code catch
It obtains signal and carries out pseudo-code tracing, the specific steps are that:
Compare plural FFT treated the maximum value and plural number FFT treated advanced acquiring pseudo code of lag acquiring pseudo code signal
The maximum value of signal:
If the maximum value of plural number FFT treated lag acquiring pseudo code signal is less than plural number FFT treated advanced acquiring pseudo code
The maximum value of signal, then local pseudo-code moves 1 sampled point to advanced direction；
If the maximum value of plural number FFT treated lag acquiring pseudo code signal is greater than plural number FFT treated advanced acquiring pseudo code
The maximum value of signal, then local pseudo-code moves 1 sampled point to lag direction；
If the maximum value of plural number FFT treated lag acquiring pseudo code signal is equal to plural number FFT treated advanced acquiring pseudo code
The maximum value of signal, then pseudo-code tracing success, i.e. spread-spectrum signal despreading are completed.
6. the spread-spectrum signal according to claim 5 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In, it is described that capturing carrier is carried out using instant acquiring pseudo code signal, the specific steps are that:
Firstly, carrying out real number FFT traction again after being multiplied using the road I in instant acquiring pseudo code signal with the road Q signal, obtain
Capturing carrier FFT signal；
Secondly, obtaining the corresponding frequency of maximum value position of capturing carrier FFT signal, as FFT lock, and then obtain
The corresponding frequency control word of FFT lock, as lock control word；
Finally, the fixed frequency control word of receiver is added with the lock control word, using frequency control after being added
Word processed controls local digital controlled oscillator and generates corresponding traction carrier wave；The frequency difference between traction carrier wave and spread-spectrum signal is calculated, if
The resolution ratio that real number FFT of the frequency difference more than or equal to K times is drawn, then repeat capturing carrier；If frequency difference is less than K times of real number
The resolution ratio of FFT traction, then capturing carrier success, obtains capture frequency；Wherein, 1≤K≤2.
7. the spread-spectrum signal according to claim 6 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In the real number FFT traction specifically: the letter obtained after being multiplied to the road I in instant acquiring pseudo code signal with the road Q signal
Number carry out J point real number FFT traction；It is positive and negative that determination frequency is handled by plural number FFT again, finally, after to J point real number FFT traction
The real and imaginary parts of signal it is squared and, obtain capturing carrier FFT signal.
8. the spread-spectrum signal according to claim 7 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In the resolution ratio of the real number FFT traction are as follows:Wherein, clk is sampling clock, and M is the cumulative points of integral, and J is real number
FFT traction points.
9. the spread-spectrum signal according to claim 1 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In, it is described that carrier track is carried out using instant acquiring pseudo code signal in step 5, the specific steps are that:
Firstly, using in instant acquiring pseudo code signal the road I and the road Q signal to carry out integral respectively cumulative, and will integral it is cumulative after
The road I and the road Q signal successively carry out phase identification, loop filtering processing, the signal after obtaining loop filtering, and then obtain loop
The corresponding frequency control word of filtered signal；
Secondly, by the corresponding frequency control word of signal after the fixed frequency control word of receiver, capture frequency and loop filtering
It sums up；The carrier wave that local digital controlled oscillator generates respective frequencies, correspondence frequency are controlled using the frequency control word after adduction
After the carrier wave of rate and the spread-spectrum signal carry out Digital Down Convert processing, be successively multiplied with instant pseudo-code branch, integrate it is tired
Add, obtain I, Q two paths of signals of carrier track, by locking decision condition, judges whether carrier track succeeds.
10. the spread-spectrum signal according to claim 9 based on more pseudo-code branch receivers de-spreads tracking, feature exists
In the locking decision condition specifically:
To in I, Q two paths of signals of carrier track the road I and the road Q signal carry out square operation respectively, it is corresponding to obtain the flat of the road I
Side, is denoted as I2, square of the road Q signal be denoted as Q2；Locking decision condition is set as I2> 2Q2；Circulation carries out 30 lockings and sentences
Certainly, when the judgement number for meeting judgment condition is greater than 20 times, then determine carrier track success, otherwise, continue carrier track,
Until carrier track success.
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