CN106788585B - Frame hopping direct expansion synchronization acquiring method based on more matched filters - Google Patents

Frame hopping direct expansion synchronization acquiring method based on more matched filters Download PDF

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Publication number
CN106788585B
CN106788585B CN201611184803.2A CN201611184803A CN106788585B CN 106788585 B CN106788585 B CN 106788585B CN 201611184803 A CN201611184803 A CN 201611184803A CN 106788585 B CN106788585 B CN 106788585B
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China
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hopping
sequence
frame
frame hopping
capture
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CN201611184803.2A
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Chinese (zh)
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CN106788585A (en
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郭士增
李岩
王孝
魏守明
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哈尔滨工业大学
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Abstract

Frame hopping direct expansion synchronization acquiring method based on more matched filters, is related to spread spectrum communication field.The present invention is to improve acquisition performance while reducing capture time to realize under the premise of keeping system complexity constant.The solution of the present invention are as follows: for inputting base-band spread-spectrum signal, the input base-band spread-spectrum signal includes M frame hopping symbol, the M frame hopping symbol is matched using M parallel matched filter, after wherein any one matched filter confirmation capture, then local frame hopping pattern is combined to realize the capture to entire code hopping sequence.The present invention is suitable for the capture systems of the frame hopping direct expansion based on more matched filter methods.

Description

Frame hopping direct expansion synchronization acquiring method based on more matched filters

Technical field

The present invention relates to spread spectrum communication fields.

Background technique

In anti-interference and the higher satellite communication of confidentiality requirement and military communication field, frame hopping direct-sequence communications system Wide application has been obtained, and frame hopping synchronization acquistion is the key technology in frame hopping direct-sequence communications system.So-called capture is practical Upper is exactly the search process for carrying out pseudo-code phase by related operation in one cycle.The acquiring pseudo code in spread spectrum receiver system The type of algorithm has very much, such as sends reference sequences, unified timing method, although the design structure of these methods is simply easy to real It is existing, but limitation is larger, performance is poor, and capture time is longer, and time-consuming is unable to complete greatly very much synchronous task.In recent years and successively There is improved Acquisition Scheme, such as relevant search, single matching matrix etc., although the acquisition performance before relatively increases, But since the general frame hopping signal period is bigger, ideally the capture period of prize law is longer, in practical applications channel Situation is complicated, after considering the factors such as falseness captures, leakage obtains, it is also difficult to complete the capture of frame hopping signal within a short period of time.

Therefore, in these current Acquisition Schemes, there is the contradiction between capture rate and system hardware complexity always: That is the improvement of acquisition performance will rise to cost with complexity.How under the premise of keeping system complexity constant, into one Step reduces capture time, improves acquisition performance, equalization point both ways is that we are pursued.Therefore in actual engineering In, under conditions of implementing and is uncomplicated there is good acquisition performance to be particularly important.

Summary of the invention

The present invention is improved and is caught while reducing capture time to realize under the premise of keeping system complexity constant Performance is obtained, to provide a kind of frame hopping direct expansion synchronization acquiring method based on more matched filters.

Frame hopping direct expansion synchronization acquiring method based on more matched filters, this method specifically:

For inputting base-band spread-spectrum signal, the input base-band spread-spectrum signal includes the code hopping sequence of M frame hopping symbol, is adopted The M frame hopping symbol is matched with M parallel matched filter, when wherein the confirmation of any one matched filter is caught After obtaining, then local frame hopping pattern is combined to realize the capture to entire code hopping sequence.

The signal processing method of each matched filter are as follows: input base-band spread-spectrum signal is separately input to N number of displacement and is posted Storage is postponed, and is then multiplied respectively with local frequency expansion sequence, and then the result after multiplication adds up, will after threshold judgement Correlation output, N is positive integer.

In acquisition procedure, local frequency expansion sequence is static constant, receives signal and carries out respectively with the local sequence of multiple spread spectrums Relevant treatment compares these relevant treatment values by comparator, selects that numerical value is maximum all the way, as the reception captured The estimated sequence of sequence.

The invention proposes a kind of new frame hopping direct expansion catching methods, it may be assumed that more matching wave filter capture methods.The present invention exists Under the premise of the degree that do not increase that the device is complicated, acquisition performance is improved significantly.From simulation result it can be seen that, more matched filterings The output of device has good sequential value correlation, and the autocorrelation peak frequency of occurrences is higher, and capture time further reduces;And more It correctly can effectively be captured under the conditions of small signal-to-noise ratio (5dB), it may be assumed that capture rate is greatly improved.In actual engineering With the application of the invention, can make in the capture systems using the frame hopping direct expansion based on more matched filter methods, performance is more in application field Well, it realizes more simply, using more extensively.

Detailed description of the invention

Fig. 1 is more matching wave filter capture schematic illustrations that the present invention is implemented;

Fig. 2 is the structural schematic diagram of matched filtering implement body unit;

Fig. 3 is more matched filter simulation data sampling number emulation schematic diagrames;

Fig. 4 is more matched filter emulation capture characteristic curve emulation schematic diagrames.

Specific embodiment

Specific embodiment one, the invention proposes the frame hopping direct expansion synchronization acquiring methods based on more matched filters, originally The main thought of invention is to realize parallel synchronization acquisition using multiple circuits and based on matched filter.

As shown in Figure 1, more matching wave filter captures be using parallel multiple matched filters to entire spread symbols into Row matches the capture to realize pseudo-code, realizes that synchronous great advantage is to realize simple, fast speed using more matched filters. It is basic to realize that module is made of digital matched filter, its main feature is that programming simple realization is flexible.Wherein digital matched filtering Device is made of delay cell, multiplier and 3 part of accumulator, concrete principle such as Fig. 2.Tap coefficient is bipolarity spreading code, defeated Enter base-band spread-spectrum signal and be first inputted to shift register, the signal of shift register is multiplied with local frequency expansion sequence, and phase Results added after multiplying obtains the correlation of two sequences.

In acquisition procedure, local sequence is static constant, receives signal and carries out relevant treatment with multiple local sequences respectively, These relevant treatment values are compared by comparator, select that numerical value is maximum all the way, as estimating for the reception sequence captured Count sequence.Correlated process, which is equivalent to, to be received signal and slips over local sequence, per a correlated results is all generated all the way, when receiving signal When sequence phase is aligned with the road, there is correlation peak, it is as a result maximum, it is believed that complete to synchronize.More matching wave filter captures The essence of method is that serial signal is carried out multidiameter delay processing, replaces time sequencing integrator with summing coupler, therefore big It saves greatly and judges the useful signal phase whether matched time.

Principle: the code hopping sequence that the hopping patterns control that the transition times period is M generates is P1P2P3P4 ... Pm, symbol week Phase is Tc, and pseudo- code length is N, and the local code phase setting of matched filter is identical as wherein some pseudo-code.Conventional matching filter Wave device captures a time minimum code-element period Tc for frame hopping signal, is up to M*N*Tc.When M is very big, it is not able to satisfy reality The needs of border application.The capture time of matched filter constrains the complexity of frame hopping pattern, the anti-intercepting and capturing of system and counterreconnaissance Ability decline.

And code hopping sequence is by the parallel processing of multiple matched filter circuits, as long as wherein some matched filter confirms Capture, so that it may the capture of entire sequence is realized in conjunction with local frame hopping pattern.For the transition times period be M hopping patterns such as Fruit uses M matched filter, and a most fast code-element period Tc may be implemented, be most slowly the capture time of N*Tc, due to frame hopping The pseudo- code length that direct expansion uses is generally all little, therefore the supper-fast capture of code hopping sequence may be implemented in more matched filter methods. It is excessive for frame hopping period M, it is difficult to realize more matched filters of corresponding number while capture, matched filter number can be reduced Amount is L.According to the phase of the equally spaced more matched filterings of setting of code hopping sequence, capture time can be reduced to greatest extent.It is right It is that P1P2P3P4 ... Pm uses L matching wave filter capture in code hopping sequence, according to the first of equally spaced setting matched filter Beginning phase is P1, P1+INT (M/L), P1+2INT (M/L) ... Pm.INT (X) expression is rounded it.At this point, system acquisition time Most short is Tc, up to INT (M/L) Tc.In practical application, the value of reasonable arrangement M and L, so that it may realize to frame hopping signal Fast Acquisition.

Then it is emulated by Matlab, has built the frame hopping direct expansion capture systems based on more matched filters, theoretically The simulation result such as Fig. 3 and Fig. 4 is obtained.

More matched filter parallel captures are used as seen from Figure 3, equally have good sequential value correlation function defeated Out, illustrate that the improvement of double matched filters will not at least increase capture difficulty;And in the output of double matched filtering systems, from phase It is higher to close the peak value frequency of occurrences, within same 2000 sampling times, the quantity of trappable point increases, that is to say, that double Matched filtering system acquisition time shortens.

From fig. 4, it can be seen that being to start correct capture near -15db, and can not correctly catch below -15db in signal-to-noise ratio It obtains, this is because the limitation of matched filter.For matched filter under low signal-to-noise ratio, the self correlated peak of code hopping sequence is buried in side In valve component, it is unable to complete capture;More matching wave filter capture methods acquisition probability when signal-to-noise ratio is 5db, just reaches 1, corresponding false-alarm probability is 0, when capture more correct than other methods it is required signal-to-noise ratio it is much lower;This explanation can normally caught It obtains in SNR ranges, the acquisition probability of double matching wave filter capture methods is higher than other methods, that is, improves identical noise Under the conditions of acquisition probability, that is, improve capture rate.

In practical application, frame hopping pattern can change at any time as needed, as long as frame hopping code character is constant, so that it may which programming changes The original state for becoming more matched filters realizes the capture of new code hopping sequence.

Claims (4)

1. the frame hopping direct expansion synchronization acquiring method based on more matched filters, this method specifically:
For inputting base-band spread-spectrum signal, the input base-band spread-spectrum signal includes the code hopping sequence of M frame hopping symbol, using simultaneously M capable matched filter matches the M frame hopping symbol, when wherein any one matched filter confirmation capture Afterwards, then local frame hopping pattern is combined to realize the capture to entire code hopping sequence, it is characterised in that the signal of each matched filter Processing method are as follows: input base-band spread-spectrum signal is separately input to N number of shift register and postpones, then respectively with local expansion Frequency sequence is multiplied, and then the result after multiplication adds up, exports correlation after threshold judgement, N is positive integer.
2. the frame hopping direct expansion synchronization acquiring method according to claim 1 based on more matched filters, it is characterised in that In acquisition procedure, local frequency expansion sequence is static constant, receives signal and carries out relevant treatment with the local sequence of multiple spread spectrums respectively, will These relevant treatment values are compared by comparator, select the estimation that numerical value is maximum all the way, as the reception sequence captured Sequence.
3. the frame hopping direct expansion synchronization acquiring method according to claim 2 based on more matched filters, it is characterised in that institute Stating input base-band spread-spectrum signal includes that M frame hopping symbol is generated by the hopping patterns control that the transition times period is M.
4. the frame hopping direct expansion synchronization acquiring method according to claim 1 based on more matched filters, it is characterised in that when When the frame hopping period is greater than preset threshold, then reducing matched filter quantity is L, and is arranged L at equal intervals according to code hopping sequence Phase with filtering, L are positive integer.
CN201611184803.2A 2016-12-20 2016-12-20 Frame hopping direct expansion synchronization acquiring method based on more matched filters CN106788585B (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1303483A (en) * 1998-04-14 2001-07-11 施耐普特拉克股份有限公司 Fast acquisition, high sensitivity GPS receiver
JP2001320303A (en) * 2000-03-03 2001-11-16 Toyo Commun Equip Co Ltd Method and device for acquiring synchronism of spread code

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1303483A (en) * 1998-04-14 2001-07-11 施耐普特拉克股份有限公司 Fast acquisition, high sensitivity GPS receiver
JP2001320303A (en) * 2000-03-03 2001-11-16 Toyo Commun Equip Co Ltd Method and device for acquiring synchronism of spread code

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Novel Fast Acquisition Algorithm for DS-FH System;Weining Song等;《2011 International Conference on Business Management and Electronic Information》;20110515;第460-462页

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