CN105141340B - The digital method of reseptance of DS msk signal - Google Patents
The digital method of reseptance of DS msk signal Download PDFInfo
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Abstract
The invention provides a kind of digital method of reseptance of DS msk signal, including：DS msk signal is configured to approximate DS-BPSK signal signal, posttectonic approximate DS-BPSK signal signal is captured using the pseudo-code phase based on Doppler effect correction FFT and the two-dimentional joint acquisition algorithm of carrier doppler frequency deviation under high dynamic environment, pseudo-code phase after capture and carrier phase are tracked, and to the signal after synchronization by de-spreading, demodulating, the processing such as detecting and recover transmission data.
Description
Technical field
The present invention relates to digital communication technology field, the present invention relates to a kind of digital communication technology, particularly a kind of DS
The digital method of reseptance of msk signal.
Background technology
At present, spread spectrum is based on BPSK, QPSK modulation system more, serious non-linear distortion, Doppler frequency shift be present
With the application field of multipath fading, DS-BPSK signal/QPSK systems can not be just applicable.DS msk signal combines spread spectrum system
Low intercepting and capturing, the random address ability of multi-user, anti-interference the advantages that and minimum frequency shift keying signal constant-envelope, frequency spectrum
The advantages that utilization rate is high, energy is concentrated, side lobe attenuation is fast, out-of-band radiation power is low, insensitive to non-linear distortion, thus fighting
The fields such as art Data-Link, civil aviation Ground-to-Air Data Link, missile guidance instruction transmission, satellite communication are widely applied.Such as
The joint tactical information distribution system (JTIDS) that U.S. army develops for Joint Army-Navy-Air Force operation, use be exactly " frequency hopping+spread spectrum+
The working method of MSK modulation ", the system are widely used in a variety of weapon platforms.
The final goal of DS msk signal receiver processing is that despread-and-demodulation goes out to send data, pseudo-code phase and carrier frequency
The capture of rate is the precondition of despread-and-demodulation, and conventional receiver is at the DS msk signal down coversion that receives mostly
Pseudo-code phase capture and carrier doppler capturing frequency deviation are carried out after reason respectively.Traditional method for acquiring pseudo code have sliding correlation method and
Matching matrix, contradiction between acquisition speed and implementation complexity be present.Simultaneously under high dynamic environment, receiver and transmitting
Very high radial velocity between machine generally be present, this causes reception signal tens KHz even hundreds of KHz Doppler's frequency to be present
Move, capture and tracking to spreading code have a huge impact.It then becomes necessary to carrier Doppler frequency is captured and mended
Repay, this is also referred to as carrier wave intercepting and capturing.Then the capture of pseudo-code signal becomes the two dimension to pseudo-code phase and carrier doppler frequency deviation
Capture, this just needs the capture time grown very much.So under high dynamic environment, how to DS msk signal that accurately and quickly
Carry out being captured as technological difficulties.
G.J.R.Povey et al. first proposed based on numerical portion matched filter and FFT combination algorithms (PMF-FFT)
Capturing Models, although this method alleviates influence of the Doppler shift to detection threshold to a certain extent, and realize
The two dimension capture of pseudo-code phase and carrier wave frequency deviation, but this method is mainly adapted to mpsk signal, and Doppler shift
Capture range it is smaller, it is still inapplicable under high dynamic environment.Thus, how accurately and rapidly to be completed under high dynamic environment
Pseudo-code phase and Doppler shift the two dimension capture of spread-spectrum signal, turn into the key technology of DS msk signal all-digital receiver.
The content of the invention
, can be by the straight of reception it is an object of the invention to provide the digital method of reseptance of a kind DS msk signal
Expand msk signal and be configured to a kind of approximate DS-BPSK signal signal form, then under large doppler Frequency Offset, DS can be used
The pseudo-code phase of bpsk signal and the two-dimentional joint acquisition algorithm of carrier doppler frequency deviation, realize DS msk signal in high dynamic
Capture and tracking under environment, avoid the complex process for directly being captured, being tracked to DS msk signal.
A kind of digital method of reseptance of DS msk signal, including：DS msk signal is configured to approximate DS-BPSK signal
Signal, using the two-dimentional joint acquisition algorithm of the pseudo-code phase based on Doppler effect correction-FFT and carrier doppler frequency deviation to construction
Approximate DS-BPSK signal signal afterwards is captured, and the pseudo-code phase after capture and carrier phase are tracked, and to synchronization after
Signal by de-spreading, demodulating, the processing such as detecting and recover transmission data.The approximate DS-BPSK signal signal is by by intermediate frequency
DS msk signal after sampling, Digital Down Convert and LPF after being multiplied with wave function extract and alternate samples structure
Make.The two-dimentional joint acquisition algorithm bag of the pseudo-code phase and carrier doppler frequency deviation based on Doppler effect correction-FFT
Include：Doppler filtering based on FFT；Doppler effect correction based on phase compensating factor and loopy moving local pseudo-code；Based on point
Section FFT pseudo-code phase parallel capture.
Using the digital method of reseptance of above-mentioned DS msk signal, the construction of the approximate DS-BPSK signal signal specifically wraps
Include：
I, Q two-way digital orthogonal baseband signal obtained after LPF respectively with wave function It is multiplied
Obtain four tunnel output signals, wherein TcFor the chip width of spreading code；
P times (P is over-sampling multiple) extraction is carried out to four tunnel output signals and obtains four road signals, respectively yI1(k’)、yQ1
(k’)、yI2(k’)、yQ2(k’)；Wherein yI1(k ') and yQ1(k ') is respectively I roadbeds band signal, Q roadbeds band signal and wave functionObtained signal, y are extracted after multiplicationI2(k ') and yQ2(k ') is respectively Q roadbeds band signal, I roadbeds band signal and ripple
Shape functionObtained signal is extracted after multiplication；Wherein k ' >=0, and be integer, the y when k ' is odd numberI1(k ') and yQ1
(k ') is 0, the y when k ' is even numberI2(k’)、yQ2(k ') is 0；
To yI1(k ') and-yI2(k ') alternate samples are as I roads, to yQ1(k ') and yQ2(k ') alternate samples, will as Q roads
I, the complex signal I+jQ that Q two paths of signals combines is approximate DS-BPSK signal signal.
Using the digital method of reseptance of above-mentioned DS msk signal, before pairing approximation DS-BPSK signal signal is captured, enter
Row is following to be handled：To posttectonic approximate DS-BPSK signal signal, the spread-spectrum signal of K PN-code capture of collection, PN-code capture N；
K*N sampling point is reordered, obtains the new sequence that N sections length is K.
Using the digital method of reseptance of above-mentioned DS msk signal, by being K point FFT to the sequence that each segment length is K,
Carry out doppler filtering.
Using the digital method of reseptance of above-mentioned DS msk signal, Doppler shift compensation includes：By Doppler shift table
It is shown asfcFor spread-spectrum code rate, Δ f is inherent spurious frequency deviation, the specific f of each of whichdIt is only corresponding
One group (k, m), wherein k and m are integer, k≤K-1, m >=0；By being multiplied by accordingly to the N section FFT results after doppler filtering
Phase compensating factorCompensationWherein i=0,1 ... N-1, j are imaginary part unit；It is local by being incited somebody to action in time domain
Pseudo-code is multiplied by oneFrequency compensationPart, it is equivalent to the FFT sequence loops of local pseudo-code on frequency domain
Move to right m positions；By suitably setting K value, inherent spurious frequency deviation Δ f is set to be not more than fc/ 2KN, so as to not influence pseudo-code below
Phase estimation.
Using the digital method of reseptance of above-mentioned DS msk signal, pseudo-code phase parallel capture is carried out using section FFT,
Including
Output signal after the shifting processing of doppler filtering, phase compensation and pseudo-code FFT sequences is carried out secondary
Reorder and revert to original order, that is, be rearranged to the sequence that K sections length is N, and the sequence that every segment length is N is carried out being based on FFT
Pseudo-code phase parallel capture, obtain the correlation output result of pseudo-code；
Decision threshold is set based on CFAR criterion；
Using envelope detected method, to correlation output result modulus, and by peak value compared with decision threshold：
(1) if peak value exceedes decision threshold, pseudo-code phase acquisition success；
(2) if peak value abandons the first segment data in K segment datas, remaining K-1 segment data is successively not less than decision threshold
Move forward, behind will continue to N point datas, after rearrangement, obtain new N sections length be K points sequence, continue to pseudo-code phase
Capture, untill peak value exceedes decision threshold.
The DS msk signal two dimension joint acquisition method of the present invention has advantages below：(1) due to DS msk signal shape
The particularity of formula, compared with the acquisition algorithm that DS-BPSK signal signal has many maturations, the catching method of DS msk signal is relatively
It is few.After DS msk signal is converted into a kind of approximate DS-BPSK signal signal form, the ripe algorithm of DS-BPSK signal is repaiied
Just available to DS msk signal after changing, the development difficulty and cost of DS MSK all-digital receivers are reduced.(2) this hair
Catching method in bright is compensated by the FFT sequences of loopy moving local pseudo-code to large doppler frequency deviation, can be facilitated
Ground expands doppler range, without reducing the performance of two dimension capture, thus is especially suitable for each under high dynamic environment
Kind application.(3) pseudo-code phase and carrier wave frequency deviation are scanned for simultaneously, reduces capture time, can meet that high data rate expands
The application demand of frequency communication.
The present invention is described further with reference to Figure of description.
Brief description of the drawings
Fig. 1 is the inventive method flow chart.
Fig. 2 is the 3-D graphic of the trapping module correlation output of the embodiment of the present invention.
Fig. 3 be the embodiment of the present invention detection probability and false-alarm probability with input signal-to-noise ratio change curve.
Fig. 4 is the all-digital receiver system composition figure of the embodiment of the present invention.
Embodiment
The intermediate-freuqncy signal that the present invention inputs can be expressed as
Wherein, γiFor the data symbol after i-th of spread spectrum of transmission, there is γi=± 1,diFor transmission
Data sequence, ciFor pseudo-code sequence,In | i |NFor | i | modulo-N arithmetic, current chip sequence numbers are represented, N is spreading code week
Phase, Tc=T/M is the chip width of spreading code, and M is spreading factor, and T is data symbol width before spread spectrum, fc=1/TcFor spread spectrum
Bit rate, fIThe number of chips differed for IF-FRE, ε for the pseudo-code signal of reception with local pseudo-code, ε TcBelieve for the pseudo-code of reception
Phase difference number with local pseudo-code, θ are the first phase of signal time of reception wave function, and θ and ε meets certain corresponding relation, i.e., For the first phase of signal time of reception carrier function, fdFor input signal and the difference of the frequency of local reference signal,
Mainly produced by Doppler effect, therefore referred to as Doppler frequency.The purpose of receiver acquisition is exactly to obtain ε, fdEstimate.
To the intermediate-freuqncy signal of input with sample frequency fs=P/Tc(P is over-sampling multiple) carries out the lower change of if sampling, numeral
After frequency is handled, obtaining I, Q two-way baseband signal is
With reference to Fig. 1, a kind of digital method of reseptance of DS msk signal, comprise the following steps：
Step S101, DS msk signal is configured to approximate DS-BPSK signal signal；
Step S102, combined using the two dimension of the pseudo-code phase based on Doppler effect correction-FFT and carrier doppler frequency deviation and caught
Algorithm is obtained to capture posttectonic approximate DS-BPSK signal signal；
Step S103, the pseudo-code phase after capture and carrier phase are tracked；
Step S104, to the signal after synchronization by de-spreading, demodulating, the processing such as detecting and recover transmission data.
In step S101, in order to eliminate the influence of modulation waveform function, by this two-way baseband signal respectively with waveform letter
NumberIt is multiplied, obtains four road signals, next carrying out P times to four road signals extracts, and obtains with TcFor
The four road signals in sampling interval.Four roadbed band signals are represented by：
γI、γQIt is γ respectivelyiTwice of obtained even order and odd numbered sequences of interpolation after progress serial to parallel conversion, and γQ
Compare γIDelay one.P times (P is over-sampling multiple) extraction is carried out to four tunnel output signals and obtains four road signals, the present invention uses
12 times, respectively yI1(k’)、yQ1(k’)、yI2(k’)、yQ2(k’)；Wherein yI1(k ') and yQ1(k ') be respectively I roadbeds band signal,
Q roadbeds band signal and wave functionObtained signal, y are extracted after multiplicationI2(k ') and yQ2(k ') is respectively Q roadbed bands
Signal, I roadbeds band signal and wave functionObtained signal is extracted after multiplication.
According to γI、γQIt is γ respectivelyiTwice of obtained even order and odd numbered sequences of interpolation after progress serial to parallel conversion, and
And γQCompare γIThe rule of delay one, to yI1、-yI2Alternate samples are as I roads, to yQ1、yQ2Alternate samples as Q roads, by I,
Q two paths of signals combines complex signal I+jQ, can obtain output signal and is
Formula (8) is the approximate DS-BPSK signal signal for being converted into DS msk signal.
In step s 102, known by the autocorrelation performance of Gold sequence, when r (k) is matched with pseudo-random sequence, on
Front and rear two in formula are independent of each other, and make sk=γ (k- ε Tc)·cosθ+j·γ(k-εTc-Tc) sin θ analyzes receiver
How the two dimension capture of pseudo-code phase and carrier doppler frequency deviation is carried out under large doppler frequency deviation.
K data symbol is received, the pseudo-code sequence that a cycle is N, i.e. reception one are included inside each data symbol
Length is K × N sequence, and sampling point is represented by r0,0,r1,0,…rK-1,0,r0,1,r1,1,…rK-1,1,……,r0,N-1,
r1,N-1,…,rK-1,N-1, reordered after being extracted to the sequence using N as interval, obtain the new sequence that N sections length is K, new sequence
Put in order as r0,0,r0,1,…r0,K-1,r1,0,r1,1,…r1,K-1,……,rN-1,0,rN-1,1,…,rN-1,K-1, in order to
More intuitively observed, this data sequence is expressed as with the form of matrix A
N row in matrix correspond to the N section sequences after reordering, and carry out doppler filtering to this N segment data, i.e., to matrix A
Each row carry out K point FFTs respectively, obtained result is expressed as with the form of matrix B
Each element of formula (10) matrix B is represented by
Wherein, ωd=2 π fdIt is the doppler angle frequency of reception signal, each specific ωdOnly correspond to one group (k, m)
Wherein k and m is integer, k≤K-1, m >=0 so that Set up, by ωdSubstitute into
Obtained to formula (11)When reception signal Doppler frequency is when on FFT frequencies, there is Δ ω=0,
Regard the row k of matrix B as a centre frequency beDoppler filtering passage, when receive believe
Number frequency existsWhen neighbouring, by doppler filtering, the most of of signal spectrum exports in k-th of filtering channel, only
There is very small part to leak into other passages.It can be seen that the exhausted big portion of useful signal make it that to the doppler filtering of reception signal
Energy is divided all to concentrate on corresponding Doppler's passage, and because the power spectrum of white Gaussian noise is all equal over the entire frequency band
Even distribution, its energy can be uniformly distributed in each channel, therefore doppler filtering also has certain noise removal function.But
It is that filtered output still includes Doppler shift, the present invention is handled each passage using the method for phase compensation,
Specific way is that Doppler filter output is multiplied by into corresponding phase compensating factor.Phase compensating factor Matrix C can represent
For
Output matrix D=B*C after phase compensation is
The frequency resolution of FFT is Δ f=f in doppler filtering processingc/ KN, no blurred bandwidth are [0, fc/ N],
When Doppler shift falls in the range of without blurred bandwidth, by doppler filtering and phase compensation, if going out on k-th of passage
Existing relevant peaks output, according to k described previously and ωdOne-to-one relationship, just can obtain the Doppler frequency of reception signal.
But under high dynamic environment, Doppler shift can typically reach tens or even hundreds of kHz, high beyond without blurred bandwidth
Doppler shift under dynamic can be expressed as For doppler filtering and
Fixed inherent spurious frequency deviation, the correlation peak that its presence can reduce pseudorandom codes phase estimation lead to not capture just after phase compensation
True pseudo-code phase, local pseudo-code is multiplied by one in time domainFrequency component can eliminate the remaining frequency of this fixation
Partially, it is equivalent to that the FFT sequence loops of local pseudo-code are moved to right into m positions on frequency domain, is always had in a passage after so handling
Output is only remaining to be not more than fc/ 2KN frequency difference Δ f, thus can be by suitably setting K value to make this residual frequency
Δ f does not interfere with pseudorandom codes phase estimation below.It can be seen that the displacement situation of hunting zone and local pseudo-code FFT result has
Close, if maximum mobile n to the leftLPosition, the n of maximum movement to the rightRPosition, then effective hunting zone of frequency is changed intoAssuming that the Doppler shift hunting zone of system requirements is [- fd,fd], then Ke YiquWhereinTo round up,Expression rounds downwards.
There is data symbol saltus step in posttectonic approximate DS-BPSK signal signal, some pseudorandom in a PN-code capture
The polarity of code, which changes, destroys its autocorrelation performance, so as to be had an impact to pseudo-code phase capture.In order to eliminate symbol
The influence of saltus step, posttectonic signal is subjected to delay multiplication.Signal Doppler frequency after delay multiplication is changed into original two
Times, so the dynamic range of Doppler frequency will also be changed into original twice in arrange parameter, and estimate Doppler frequency
Afterwards real Doppler frequency is only except 2.
It is corresponding with signal Doppler frequency after the shifting processing of doppler filtering, phase compensation and pseudo-code FFT sequences
K-th of multi-channel output signal be
Next, carrying out secondary reorder to the output signal after processing reverts to original order, that is, it is long to be rearranged to K sections
For N sequence, and the pseudo-code phase parallel capture based on FFT is carried out to the sequence that every segment length is N, i.e., whole sequence is based on
The pseudo-code phase parallel capture of section FFT obtains the correlation output result of pseudo-code.
Pseudo-code phase parallel capture based on FFT adds an IFFT to replace matched filtering, local pseudo-code using FFT twice
Sequence { ciFFT loopy movings to the rightThe result of position can regard sequence asCarry out FFT result.Final base
It is in Doppler effect correction-FFT two dimension capture output result：
WhenWhen, have
The method that acquiring pseudo code in the system is set using envelope detected and CFAR thresholding.To IFFT output result
Modulus, and by correlation peak compared with decision threshold, if correlation peak is more than decision threshold, then it represents that pseudo-code phase is caught
Succeed, the frequency residing for peak value is exactly the estimate of Doppler frequency, and residing phase is exactly the estimate of pseudo-code phase；Such as
Fruit correlation peak is not above decision threshold, then it represents that without acquisition success, the first segment data in K segment datas abandoned, its
Remaining K-1 segment datas move forward successively, behind will continue to N point datas reset after, obtain new N sections length be K points sequence
Continue fast Acquisition processing, untill correlation peak is more than decision threshold, complete pseudo-code phase capture.
In step S103 and step S104, above-mentioned fast Acquisition processing module is carried out to pseudo-code phase and Doppler shift
Rough estimate, want to de-spread from reception signal, demodulate transmission data, also to carry out essence synchronously, i.e., to pseudo-code phase and carrier wave
Phase is tracked, and the present invention realizes pseudo-code phase and carrier wave phase respectively using lead-lag delay phase-locked loop, Costas loop
The tracking of position.After completing pseudo-code phase and carrier frequency synchronization, despreading, demodulation detection module are entered, is finally recovered
Send data symbol.
The present invention is received using the system shown in Fig. 4 to DS msk signal, system sampling frequency fs=
245.52MHz, IF-FRE 76.725MHz, over-sampling multiple P=12, spread-spectrum code rate 20.46Mchip/s, data speed
Rate is 20kbps, and spreading code uses Gold sequence, code length N=1023, and the code periodicity of two-dimensional search, i.e. K values are 32, Doppler
Frequency range is [- 200KHz, 200KHz], therefore nL=20, nR=20, frequency search stepping is 625Hz, and pseudo-code searches for stepping
For a chip.
With reference to Fig. 2, input signal-to-noise ratio SNR=-15dB, pseudo-code phase ε=478.4chip, Doppler frequency fd=
During 169.85KHz, the two-dimensional search of pseudo-code phase and carrier doppler frequency deviation is carried out, obtains normalizing the graphics of correlation output
Shape.As can be seen from the figure the estimate of pseudo-code phase differs 0.4chip with actual value, in the range of half-chip；Carrier frequency
Inclined estimate differs 162.5Hz with actual value, in the range of maximum residual frequency difference.It can be seen that digital connecing of designing of the present invention
Receiving method can be under high dynamic environment to DS msk signal pseudo-code phase and carrier wave frequency deviation carry out quick and accurately catch
Obtain.
With reference to Fig. 3, input signal-to-noise ratio is SNR=[- 30dB, -5dB], fd=40KHz, false-alarm probability PfWhen=0.01, enter
5000 captures of row, obtain the change curve of detection probability and false-alarm probability with signal to noise ratio.As a result find when signal to noise ratio reaches-
After 17dB, detection probability levels off to 1, and as a result of CFAR thresholding design standard, false-alarm probability is hardly by signal to noise ratio
Influence.
Claims (7)
- A kind of 1. digital method of reseptance of DS msk signal, it is characterised in that includingDS msk signal is configured to approximate DS-BPSK signal signal,Using the two-dimentional joint acquisition algorithm of the pseudo-code phase based on Doppler effect correction-FFT and carrier doppler frequency deviation to construction Approximate DS-BPSK signal signal afterwards is captured,Pseudo-code phase and carrier phase are tracked,To the signal after synchronization by de-spreading, demodulating, detection process recovers transmission data；The approximate DS-BPSK signal signal is by the DS msk signal after if sampling, Digital Down Convert and LPF Extracted after being multiplied with wave function and alternate samples construct what is formed；The two-dimentional joint acquisition algorithm of the pseudo-code phase and carrier doppler frequency deviation based on Doppler effect correction-FFT includes：Doppler filtering based on FFT；Doppler effect correction based on phase compensating factor and loopy moving local pseudo-code；Pseudo-code phase parallel capture based on section FFT；The construction of the approximate DS-BPSK signal signal specifically includes：I, Q two-way digital orthogonal baseband signal obtained after LPF respectively with wave function Multiplication obtains Four tunnel output signals, wherein TcFor the chip width of spreading code；Four tunnel output signals are carried out with P times and extracts to obtain four road signals, P is over-sampling multiple, respectively yI1(k), yQ1(k), yI2(k), yQ2(k)；Wherein yI1(k) and yQ1(k) is respectively I roadbeds band signal, Q roadbeds band signal and wave functionObtained signal, y are extracted after multiplicationI2(k) and yQ2(k) is respectively Q roadbeds band signal, I roadbeds band signal and ripple Shape functionObtained signal is extracted after multiplication；Wherein k, >=0, and be integer, work as k, y when being odd numberI1(k) and yQ1 (k) is 0, works as k, y when being even numberI2(k), yQ2(k) is 0；To yI1(k) and-yI2(k) alternate samples are as I roads, to yQ1(k) and yQ2(k) alternate samples are as Q roads, by I, Q two The complex signal I+jQ that road signal combines is approximate DS-BPSK signal signal.
- 2. the digital method of reseptance of DS msk signal according to claim 1, it is characterised in that in pairing approximation DS Before bpsk signal is captured, following handle is carried out：To posttectonic approximate bpsk signal, the spread-spectrum signal of K PN-code capture of collection, PN-code capture N；K*N sampling point is reordered, obtains the new sequence that N sections length is K.
- 3. the digital method of reseptance of DS msk signal according to claim 2, it is characterised in that by each section A length of K sequence is K point FFT, carries out doppler filtering.
- 4. the digital method of reseptance of DS msk signal according to claim 2, it is characterised in that Doppler effect correction bag Include：Doppler shift is expressed asfcFor spread-spectrum code rate, Δ f is inherent spurious frequency deviation,The specific f of each of whichdOne group (k, m) only is corresponded to, wherein k and m are integer, k≤K-1, m >=0；By being multiplied by corresponding phase compensating factor to the N section FFT results after doppler filteringCompensationWherein i= 0,1 ... N-1, j are imaginary part unit；By the way that local pseudo-code is multiplied by into one in time domainFrequency compensationBeing equivalent on frequency domain will be local The FFT sequence loops of pseudo-code move to right m positions；By suitably setting K value, inherent spurious frequency deviation Δ f is set to be not more than fc/ 2KN, so as to which the pseudo-code phase not influenceed below is estimated Meter.
- 5. the digital method of reseptance of DS msk signal according to claim 4, it is characterised in that entered using section FFT Row pseudo-code phase parallel capture, including：Secondary rearrangement is carried out to the output signal after the shifting processing of doppler filtering, phase compensation and pseudo-code FFT sequences Sequence reverts to original order, that is, is rearranged to the sequence that K sections length is N, and carry out the puppet based on FFT to the sequence that every segment length is N Code phase parallel capture, obtain the correlation output result of pseudo-code；Decision threshold is set based on CFAR criterion；Using envelope detected method, to correlation output result modulus, and by peak value compared with decision threshold：(1) if peak value exceedes decision threshold, pseudo-code phase acquisition success；(2) if peak value is not less than decision threshold, the first segment data in K segment datas is abandoned, remaining K-1 segment data is successively forward It is mobile, behind will continue to N point datas, after rearrangement, obtain the sequence that new N sections length is K points, continue to catch pseudo-code phase Obtain, untill peak value exceedes decision threshold.
- 6. the digital method of reseptance of DS msk signal according to claim 1, it is characterised in that using lead-lag Delay lock loop, Costas loop realize the tracking of pseudo-code phase and carrier phase respectively.
- 7. the digital method of reseptance of DS msk signal according to claim 1, it is characterised in that using coherent demodulation, Feedback judgement detection method carries out processing to the msk signal after despreading and recovers transmission data.
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| CN105790788B (en) * | 2016-04-28 | 2019-01-15 | 南京理工大学 | A kind of pseudo-code of direct expansion msk signal-Doppler's joint acquisition method |
| CN107493117B (en) * | 2016-06-12 | 2019-08-09 | 南京理工大学 | The two-dimentional joint acquisition method of direct expansion msk signal under a kind of high dynamic |
| CN106209160B (en) * | 2016-06-29 | 2019-01-11 | 南京理工大学 | A kind of compressed sensing based direct expansion msk signal two dimension joint acquisition method |
| CN106506037B (en) * | 2016-10-25 | 2018-09-25 | 湖北航天技术研究院总体设计所 | A kind of demodulation method of incoherent spread spectrum communication system |
| CN106842252A (en) * | 2016-12-30 | 2017-06-13 | 北京航空航天大学 | A kind of detection method of the relevant joint acquisition subcode based on delay multiplication |
| CN109412644B (en) * | 2018-09-13 | 2021-02-12 | 南京理工大学 | Doppler frequency estimation method for direct sequence spread spectrum MSK signal |
| CN110113280B (en) * | 2019-04-12 | 2021-11-23 | 杭州电子科技大学 | Anti-frequency-offset GMSK demodulation synchronization method in burst communication |
| CN110300079B (en) * | 2019-07-19 | 2020-06-05 | 北京理工大学 | MSK signal coherent demodulation method and system |
| CN110474658B (en) * | 2019-08-29 | 2021-05-25 | 北京航空航天大学合肥创新研究院 | DS/FH hopping spread data transmission signal capturing method based on long code phase assistance |
| CN111510410B (en) * | 2020-01-02 | 2021-03-26 | 北京理工大学 | Anti-interference DS-GMSK receiving method and device suitable for satellite communication |
| CN111953379B (en) * | 2020-08-24 | 2021-11-05 | 沈阳理工大学 | Universal method for enhancing comprehensive performance of direct sequence spread spectrum communication system |
| CN112910819B (en) * | 2021-01-29 | 2022-07-08 | 东方红卫星移动通信有限公司 | Deep spread spectrum low-orbit satellite carrier synchronization method and system in high dynamic scene |
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