CN101702628A - Pseudo code capturing method and capturing device using multiple antennae of direct sequence spread spectrum system - Google Patents

Abstract

The invention provides a pseudo code capturing method and device using multiple antennae of a direct sequence spread spectrum system. The method comprises the following steps: (1) each antenna uses one capture branch to determine self-adaptive weight vector by combining capture branch output according to the space correlation matrix of the received signal acquired by each antennae; (2) the capture branch output is subjected to weighted sum by using the self-adaptive weight vector in the step (1) so as to output decision statistics; and (3) the captured decision statistics is compared with a threshold to make a decision, if the captured decision statistics is more than or equal to the threshold, a tracking phase is carried out; otherwise, the PN code phase position of a local PN code relatively to the received signal is converted and the above processes are repeatedly carried out. The device comprises an analog digital conversion unit, digital down-conversion unit, a correlator unit, a captured decision statistic calculation unit and a threshold comparison unit. The device has the advantages of simple structure, strong interference resistance, independent decision threshold to signal-to-interference and noise ratio and the like.

Description

Resistant DS Spread Spectrum System is used the method for acquiring pseudo code and the acquisition equipment of many antennas

Technical field

The present invention is mainly concerned with the direct sequence spread spectrum skill field, refers in particular to method for acquiring pseudo code and equipment that Resistant DS Spread Spectrum System is used many antennas.

Background technology

Resistant DS Spread Spectrum System has good anti-interference, the anti-performance of intercepting and capturing, and can also be used to realize code division multiple access, range finding and timing, thereby obtain using widely in communication, location and navigation, TT﹠C system etc.

In Resistant DS Spread Spectrum System, the signal that receiver wants correct demodulate reception to arrive must make at first that the pseudo random sequence (also claiming the PN sign indicating number, pseudo-code) in the receiver realizes regularly synchronously with received signal PN sequence.This synchronizing process be divided into two the step realize, promptly catch and follow the tracks of.By acquisition phase, the timing error that makes local PN sign indicating number sequence and receive PN sign indicating number sequence is less than a chip, in a part chip range, so catch and be called thick (coarse synchronization) synchronously.After acquisition procedure is finished, make the timing error of local pseudo random sequence continue to reduce through the code tracking loop, track loop also will be followed the tracks of pseudo random sequence variation regularly, and this process is also referred to as thin (fine synchronization) synchronously.Because directly-enlarging system can't be realized communication the PN sign indicating number is caught before, so the PN sign indicating number of spread spectrum system reception and starting stage catches task primary when being operate as normal, also is one of the most challenging task.

The PN sign indicating number catches the correlation properties that are based on the PN sign indicating number in the Resistant DS Spread Spectrum System.In realization, generally carry out, only received signal need be carried out relevant getting final product with the local pseudo-code sequence of out of phase by means of the pilot frequency sequence that sends.The implementation that the PN sign indicating number is caught roughly can be summed up as three kinds: slip correlation capturing mode, matching wave filter capture mode, sequence estimation acquisition mode.Wherein, the sequence estimation acquisition mode proposes the earliest, but therefore this method poor-performing when low signal-to-noise ratio is seldom used in real system.Matched-filter approach can realize catching fast of PN sign indicating number, the early stage matched filtering of using simulated sound surface wave (SAW) device or charge-coupled device (CCD) to realize the PN sign indicating number, use digital form to realize matched filter now in the all-digital receiver system, matched filter generally is made up of the memory circuit of one group of multiplier, an integrator and the tap of two bands, its lock in time is short, but circuit complexity and power consumption are bigger.Sliding correlation detector is made up of a multiplier and an integrator.Received signal and local spread-spectrum pseudo code multiply each other, and output adds up integrator to multiplier in the time of integration.Integrator is output as the correlation of this phase point.Because implementation structure is simple, thereby be that present real system is especially used maximum a kind of PN sign indicating number acquisition modes in the all-digital signal.But the capture time of sliding correlation detector method is longer, especially under the situation that PN sign indicating number sequence is long and under the situation of low Signal to Interference plus Noise Ratio.Catching method commonly used at present is mostly on the basis of sliding correlation detector acquisition mode, takes some measures to reduce capture time, for example uses the acquisition mode of parallel capture and serial The parallel combined.Catching method also combines with different search and verification strategy, as the fixing resident strategy of single, repeatedly fix resident strategy, variable residence time strategy etc., develops on this basis and various improved PN sign indicating number acquisition modes, improves acquisition performance.

Along with multiaerial system (being called array antenna in the documents and materials that have) in Application in Communication Systems, relevant input has had all multi-methods to be studied and to propose, and uses the code capture method of many antennas also to cause people's attention.After using many antennas, the desired user signal can be worked under lower Signal to Interference plus Noise Ratio condition, and at this moment traditional single antenna catching method poor-performing uses many antennas can suppress to disturb when catching, improve the Signal to Interference plus Noise Ratio of received signal, thereby improve the detection performance that sign indicating number is caught.In the time of in the applied environment that runs into strong artificial disturbance, when catching, use many antennas to suppress strong jamming, provide anti-interference protection signal in the spatial domain.

When array antenna was used to detect, a kind of method was to use many antennas to carry out space diversity reception, and when diversity, antenna spacing should be enough big, so that the decline of the signal that each antenna receives is independent mutually.Angle spread is depended at required interval, the angular range of spatially being crossed over when it is received signal arrival reception antenna.Another kind method just is to use intelligent antenna technology to carry out wave beam and forms, and forms by wave beam and suppresses to disturb to improve the Signal to Interference plus Noise Ratio of received signal.

Be used to detect similar with many antennas, use the catching method of many antennas also can be divided into two classes.

One class is to use many antennas to carry out diversity reception when catching, referring to document Oh-Soon Shin and Kwang Bok Lee, Use of Multiple Antennas for DS/CDMA Code Acquisition[J], IEEE Trans.Wireless Commun., 2003,2 (3): 424-430. (Oh-Soon Shin and Kwang Bok Lee, the sign indicating number that uses many antennas to be used for straight expansion/code division multiple access system is caught, IEEE radio communication transactions, 2003,2 (3): 424-430.) with document R.R.Rick and L.B.Milstein, Parallel acquisition of spread-spectrum signals with antenna diversity[J], IEEE Trans.Commun., 1997,45 (8): 903-905 (R.R.Rick and L.B.Milstein, use antenna diversity to carry out the parallel capture of spread spectrum signal, the ieee communication transactions, 1997,45 (8): 903-905) incoherent the catching of traditional single antenna expanded to that multi-antenna diversity is incoherent catches, the output that a plurality of array elements receive after the signal incoherent merging after the despreadings is adjudicated.The method of diversity reception generally is used for having between a plurality of reception antennas very big array element situation at interval, at this moment can think that sending signal arrives receiver through a plurality of independently transmission channels, the signal that each reception antenna receives is independently, can improve the influence of signal to noise ratio and inhibition decline by diversity reception.In the method that has a plurality of bays are divided into groups, the antenna in each group is tested to different code phases and is adjudicated, and, but has increased for reducing the required antenna amount of capture time reducing mean acquisition time by such grouping.

Another kind of method is that the signal that when catching many antennas is received carries out wave beam formation to suppress to disturb and improve Signal to Interference plus Noise Ratio, document B.Wang and H.M.Kwon for example, PN code acquisition using smart antenna for spread-spectrumwireless communications-I[J], IEEE Trans on Vehicular Technology, 2003,52 (1): 142-149 (B.Wang and H.M.Kwon, use smart antenna to be used for the pseudo-random code catching of spectrum spread wireless communication, IEEE mobile technology transactions, 2003,52 (1): use normalization minimum mean-square calculation (NLMS) to obtain the weight vector of spatial domain weighting 142-149), weight convergence is slow in adaptive process, and its acquisition performance is difficult to carry out theory analysis accurately.

In the wireless communication system in modern times, when generally being, the parameter of communication channel becomes, particularly under the wireless mobile communications environment, since the time become the influence of decline, multipath transmission, interference etc., the input signal of receiver and Signal to Interference plus Noise Ratio all can change, this situation is caught the PN sign indicating number and has been proposed some new requirements, because use fixing certain threshold can only obtain best acquisition performance in very little signal to noise ratio scope.In the spread spectrum communication system of reality, often need to consider that receiver realizes reliably catching of PN sign indicating number in wide signal to noise ratio scope or even in the omnidistance dynamic range of input signal-to-noise ratio, at this moment just need to use self-adaptive decision threshold.

Summary of the invention

The technical problem to be solved in the present invention just is: at the technical problem that prior art exists, the invention provides method for acquiring pseudo code and device that a kind of Resistant DS Spread Spectrum System with characteristics such as simple in structure, that antijamming capability strong, can realize that self adaptation that decision threshold and Signal to Interference plus Noise Ratio have nothing to do is caught is used many antennas.

For solving the problems of the technologies described above, the solution that the present invention proposes is:

A kind of Resistant DS Spread Spectrum System is used the method for acquiring pseudo code of many antennas, it is characterized in that step is:

1., each antenna uses one and catches branch road, obtains the spatial correlation matrix of received signal according to each antenna receiving signal, in conjunction with catching the definite adaptive weight vector of branch road output;

2., the adaptive weight vector that uses above-mentioned steps to obtain in 1. is weighted summation to catching branch road output, output is as the statistic of prize judgment;

3., the statistic of prize judgment that above-mentioned steps is obtained in 2. and thresholding compare and make judgement, if the statistic of prize judgment greater than thresholding, then changes tracking phase over to; Otherwise conversion is caught local PN sign indicating number in the branch road with respect to the PN code phase of received signal, repeats said process.

Described step idiographic flow 1. is:

I, the sampling of baseband signal of obtaining the received signal of each bay;

II, each array element baseband sampling signal are caught branch road by one, obtain the relevant output with local pseudo-code signal, and the relevant output of a plurality of branch roads constitutes an output vector

Wherein () ^*Expression is gripped altogether, X=[x (1), and x (2) ..., x (N)] and the signal matrix formed by the array received signal vector between the area of observation coverage, d=[d (1), d (2) ..., d (N)] ^TIt is reference signal vector, d (i)=c (i-Δ τ), c (i) expression received signal PN sign indicating number is in the value of sampling instant i, Δ τ is the phase difference that receives PN sign indicating number and local PN sign indicating number, Δ τ=0 when the PN sign indicating number is synchronous, y is that the array received signal between the area of observation coverage carries out relevant output with reference signal, i.e. output vector after the despreading computing;

Obtain spatial correlation matrix after III, the signal process part correlation computing according to receiving array, spatial correlation matrix is determined by following formula: x ₁(i), i=1 ..., L determines according to following process: to piecemeal between the area of observation coverage, the data sampling point of each data block is K, and K is a little positive integer.If it is the integral multiple of K that observation detects N, then be divided into L=N/K data block between the area of observation coverage, each data block sampling point quantity is K.If N can not be divided exactly by L, be divided between the area of observation coverage

Individual data block, here

Round operation in the expression, at this moment preceding L-1 section has K measured value for every section, and final stage has K measured value of N-(L-1).In each piece, the dateout of utilizing data in this data block and reference signal to carry out behind the part correlation is calculated correlation matrix.If N can be divided exactly by L, the dateout behind the part correlation is

If N can not be divided exactly by L, then the dateout behind the part correlation can be expressed as $x_1\left(i\right)=\frac{1}{K}\underset{j=1}{\overset{K}{\mathrm{\Σ}}}x((i-1)K+j)d^{*}((i-1)K+j),i=\mathrm{1,2},\·\·\·,L-1,$ $x_1\left(L\right)=\frac{1}{N-(L-1)K}\underset{j=N-(L-1)*K+1}{\overset{N}{\mathrm{\Σ}}}x\left(j\right)d^{*}\left(j\right).$

IV, calculate the adaptive array weights in conjunction with spatial correlation matrix and a plurality of output vector of catching branch road $\hat{w}={\hat{R}}_{x_1}^{-1}{\hat{r}}_{\mathrm{xd}}.$

As a further improvement on the present invention:

Described thresholding is determined according to the integration lengths of false alarm probability, antenna amount, sliding correlation detector.

Described false alarm probability is

Here B () expression beta function, β _TBe threshold value.

As a further improvement on the present invention: the invention provides the acquiring pseudo code device that a kind of Resistant DS Spread Spectrum System is used many antennas, it is characterized in that, comprising:

The analog-to-digital conversion unit is used for receiving the Direct Sequence Spread Spectrum Signal after radio frequency unit is handled that each antenna is sent here, and this signal is carried out sample quantization;

The Digital Down Convert unit receives the received signal behind the sample quantization that transmits through the analog-to-digital conversion unit, carries out down-conversion and obtains digital baseband signal;

Correlator unit receives the digital baseband signal that transmits through the Digital Down Convert unit, and this digital baseband signal and local pseudo-code are carried out the relevant output that adds up;

Prize judgment statistic computing unit receives the digital baseband signal that transmits through the Digital Down Convert unit, obtains spatial correlation matrix, and determines spatial domain weights and decision statistic amount according to the output of spatial correlation matrix and correlator unit;

The thresholding comparing unit is preset with decision threshold, and decision statistic amount and decision threshold are compared judgement, if the decision statistic amount greater than decision threshold, then changes tracing process over to; If the decision statistic amount, then changes local pseudo-code less than decision threshold with respect to the phase place that receives pseudo-code, calculate the decision statistic amount according to received signal again, carry out threshold judgement, up to realize catching change tracing process over to till.

Described prize judgment statistic computing unit comprises spatial correlation matrix computing unit, spatial domain weight calculation unit and spatial domain weighted units.

Described Digital Down Convert unit comprises carrier generator, and the carrier signal that received signal behind the sample quantization that transmits through the analog-to-digital conversion unit and described carrier generator the produce realization down-conversion that multiplies each other obtains digital baseband signal.

As a further improvement on the present invention: the invention provides the acquiring pseudo code device that a kind of Resistant DS Spread Spectrum System is used many antennas, it is characterized in that, comprising:

The analog-to-digital conversion unit is used for receiving the Direct Sequence Spread Spectrum Signal after radio frequency unit is handled that each antenna is sent here, and this signal is carried out delivering to respectively behind the sample quantization in the capture component more than one group;

Described every group of capture component includes Digital Down Convert unit, correlator unit, prize judgment statistic computing unit; Described Digital Down Convert unit receives the received signal behind the sample quantization that transmits through the analog-to-digital conversion unit, carries out down-conversion and obtains digital baseband signal; Described correlator unit receives the digital baseband signal that transmits through the Digital Down Convert unit, and this digital baseband signal and local pseudo-code are carried out the relevant output that adds up; Described prize judgment statistic computing unit receives the digital baseband signal that transmits through the Digital Down Convert unit, obtains spatial correlation matrix, and determines spatial domain weights and decision statistic amount according to the output of spatial correlation matrix and correlator unit;

The maximum selected cell receives the decision statistic amount that every group of capture component exported, and selects one of maximum to deliver to the thresholding comparing unit.

The thresholding comparing unit is preset with decision threshold, and decision statistic amount and decision threshold are compared judgement, if the decision statistic amount greater than decision threshold, then changes tracing process over to; If the decision statistic amount, then changes local pseudo-code less than decision threshold with respect to the phase place that receives pseudo-code, calculate the decision statistic amount according to received signal again, carry out threshold judgement, up to realize catching change tracing process over to till.

Described prize judgment statistic computing unit comprises spatial correlation matrix computing unit, spatial domain weight calculation unit and spatial domain weighted units.

Described Digital Down Convert unit comprises carrier generator, and the carrier signal that received signal behind the sample quantization that transmits through the analog-to-digital conversion unit and described carrier generator the produce realization down-conversion that multiplies each other obtains digital baseband signal.

Compared with prior art, advantage of the present invention just is:

1, Resistant DS Spread Spectrum System of the present invention is used the method for acquiring pseudo code and the device of many antennas, be applicable to that mainly pseudo random sequence acquiring pseudo code and spatial domain weights in the Resistant DS Spread Spectrum System of using many antennas catch, when carrying out acquiring pseudo code, utilize the antijamming capability of array, improved the acquiring pseudo code performance; Acquiring pseudo code device of the present invention, simple and practical, complexity is low, is convenient to Digital Realization.

2, Resistant DS Spread Spectrum System of the present invention is used the method for acquiring pseudo code and the device of many antennas, owing to used weight calculation method based on spatial correlation matrix, compare with the method that obtains the spatial domain weights by some adaptive training processes, Acquisition Detection probability height, the spatial domain weight convergence is fast, acquisition performance can be analyzed accurately, and decision threshold can be by calculating accurately.

3, Resistant DS Spread Spectrum System of the present invention is used the method for acquiring pseudo code and the device of many antennas, owing to used weight calculation method based on spatial correlation matrix, therefore the Signal to Interference plus Noise Ratio of decision threshold and received signal is irrelevant, can realize the reliable acquiring pseudo code in the big Signal to Interference plus Noise Ratio scope.

4, Resistant DS Spread Spectrum System of the present invention is used the method for acquiring pseudo code and the device of many antennas, and versatility is stronger, can combine with the carrier doppler search; Go for pseudo-code spreading ratio arbitrarily, both can be used for catching of periodically short pseudo-code, also can be used for catching of long acyclic pseudo-code.

Description of drawings

Fig. 1 is the schematic flow sheet of catching method of the present invention;

Fig. 2 is the frame structure schematic diagram of acquisition equipment embodiment 1 of the present invention;

Fig. 3 is the frame structure schematic diagram of acquisition equipment embodiment 2 of the present invention.

Marginal data

100, analog-to-digital conversion unit; 101, analog digital converting unit; 110, Digital Down Convert unit; 111, carrier generator; 120, correlator unit; 121, local pseudo-code generator; 122, relevant accumulator; 130, prize judgment statistic computing unit; 131, spatial correlation matrix computing unit; 132, spatial domain weight calculation unit; 133, spatial domain weighted units; 140, thresholding comparing unit; 141, thresholding setup unit; 142, comparator; 200, capture component; 300, maximum selected cell.

Embodiment

Below with reference to specific embodiment and Figure of description the present invention is described in further details.

As shown in Figure 1, Resistant DS Spread Spectrum System of the present invention is used the method for acquiring pseudo code of many antennas, basic process is: each antenna uses one and catches branch road, obtains the spatial correlation matrix of received signal according to each antenna receiving signal, in conjunction with catching the definite adaptive weight vector of branch road output; The adaptive weight vector that obtains in the use is weighted summation to catching branch road output, and output is as the statistic of prize judgment; The statistic of prize judgment and thresholding compared make judgement, if the statistic of prize judgment greater than thresholding, then changes tracking phase over to; Otherwise conversion is caught local PN sign indicating number in the branch road with respect to the PN code phase of received signal, repeats said process.

Resistant DS Spread Spectrum System of the present invention uses the detailed process of the method for acquiring pseudo code of many antennas to be:

Step S1: at first carry out initialization, parameter N, M, K, thresholding β in the initialization system _T

Step S2: the sampling of obtaining the baseband signal of each bay received signal at step S2.After the signal process radio frequency unit amplification filtering that antenna receives, obtain baseband signal through down-conversion and sample; Perhaps to if signal sampling, Digital Down Convert is to base band then.If to the baseband signal sampling, then down-converter unit can also be used to carry out the search of carrier doppler.Suppose to obtain array sampling snap in the observation time N time, receiving terminal aerial array array element quantity is M, and the array data vector that obtains the i time snap is

x(i)＝[x ₁(i)，x ₂(i)，…，x _M(i)] ^T (1)

Here () ^TThe computing of expression transposition, i=1 ... N is the numbering of sampling instant and data, and with this as time reference.

Reception data matrix between the area of observation coverage is X=[x (1), x (2) ..., x (N)].

Step S3, each array element baseband sampling signal are caught branch road by one, obtain the relevant output with local pseudo-code signal, and the relevant output of a plurality of branch roads constitutes an output vector.

${\hat{r}}_{\mathrm{xd}}=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}x\left(i\right)d^{*}\left(i\right)=\frac{1}{N}{\mathrm{Xd}}^{*}=y---\left(2\right)$

Here, () ^*Expression is gripped altogether.D=[d (1), d (2) ..., d (N)] ^TBe reference signal vector, d (i)=c (i-Δ τ), c (i) expression received signal PN sign indicating number is in the value of sampling instant i, and Δ τ is the phase difference that receives PN sign indicating number and local PN sign indicating number, Δ τ=0 when the PN sign indicating number is synchronous.Y is that the array received signal between the area of observation coverage carries out relevant output with reference signal, i.e. output vector after the despreading computing.

Step S4, according to the signal of receiving array through the part correlation computing after the computer memory correlation matrix.

To piecemeal between the area of observation coverage, the data sampling point of each data block is K, and K is a little positive integer.If it is the integral multiple of K that observation detects N, then be divided into L=N/K data block between the area of observation coverage, each data block sampling point quantity is K.If N can not be divided exactly by L, be divided between the area of observation coverage

Individual data block, here

Round operation in the expression, at this moment preceding L-1 section has K measured value for every section, and final stage has K measured value of N-(L-1).In each piece, the dateout of utilizing data in this data block and reference signal to carry out behind the part correlation is calculated correlation matrix.If N can be divided exactly by L, the dateout behind the part correlation can be expressed as

$x_1\left(i\right)=\frac{1}{K}\underset{j=1}{\overset{K}{\mathrm{\Σ}}}x((i-1)K+j)d^{*}((i-1)K+j),i=\mathrm{1,2},\·\·\·,L---\left(3a\right)$

If N can not be divided exactly by L, then the dateout behind the part correlation can be expressed as

$x_1\left(i\right)=\frac{1}{K}\underset{j=1}{\overset{K}{\mathrm{\Σ}}}x((i-1)K+j)d^{*}((i-1)K+j),i=\mathrm{1,2},\·\·\·,L-1$

$x_1\left(L\right)=\frac{1}{N-(L-1)K}\underset{j=N-(L-1)*K+1}{\overset{N}{\mathrm{\Σ}}}x\left(j\right)d^{*}\left(j\right)---\left(3b\right)$

Spatial correlation matrix is determined by following formula

${\hat{R}}_{x_1}=\frac{1}{L}\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{x}_1\left(i\right)x_1^H\left(i\right)---\left(4\right)$

Step S5, calculate the adaptive array weights in conjunction with spatial correlation matrix and a plurality of output vector of catching branch road.

$\hat{w}={\hat{R}}_{x_1}^{-1}{\hat{r}}_{\mathrm{xd}}---\left(5\right)$

Step S6, be weighted according to a plurality of output vectors of catching branch road

$z={\hat{w}}^{H}y=y^H{\hat{R}}_{x_1}^{-1}y---\left(6\right)$

Step S7, weighting output z and decision threshold β _TCompare.For single search strategy that stops,, otherwise change step S9 over to if decision statistic amount z then changes step S8 over to less than thresholding.Thresholding requires to determine according to system parameters and performance index.These parameters comprise the integration lengths of false alarm probability, antenna amount, sliding correlation detector.

The false alarm probability of above-mentioned detection method can obtain with following formula:

$P_F={\∫}_{{\mathrm{\β}}_T}^1\frac{1}{B(M,L-M)}{x}^{M-1}{(1-x)}^{L-M-1}\mathrm{dx}---\left(7\right)$

Here B () expression beta function.According to the false alarm probability of system requirements, antenna amount, observation detects length, and number of fragments can be determined decision threshold β by numerical computations _TFor the canonical parameter of the many groups in the practical application, can calculate thresholding and storage in advance, when initialization, read corresponding decision threshold according to system parameters.

If z is less than thresholding for step S8 decision statistic amount, then change step S8 over to, change local pseudo-code with respect to the phase place that receives pseudo-code, repeat the process of above-mentioned steps S2 to S7.

If z is more than or equal to thresholding for step S9 decision statistic amount, then change step S9 over to, with the pseudo-code timing adaptive weights output of catching, acquisition procedure finishes, and changes the pseudo-code tracing stage over to.

Be at the situation of not using the carrier doppler search in describing above.For the situation that has carrier doppler (owing to receiving and dispatching the frequency departure that carrier frequency offset, the motion of receiving-transmitting sides, the Doppler frequency shift of transmission signals etc. cause) search, the method for acquiring pseudo code that proposes among the present invention can combine with doppler searching.

The acquiring pseudo code device can combine with parallel doppler search, at this moment uses a plurality of acquiring pseudo codes and spatial domain weights capturing unit.Carrier generator produces the carrier wave of different frequency, and sampled data uses the carrier wave of different frequency to carry out down-conversion, delivers to acquiring pseudo code and spatial domain weights capturing unit then respectively, selects a maximum value to carry out prize judgment from a plurality of prize judgment statistics.In each acquiring pseudo code and spatial domain weights capturing unit, basic step and above-described process are similar.

The acquiring pseudo code device can combine with the carrier doppler serial search, and the frequency that changes carrier generator is within the specific limits carried out serial search, at this moment only uses single acquiring pseudo code and spatial domain weights capturing unit.

Based on above-mentioned method for acquiring pseudo code, the present invention and then a kind of acquiring pseudo code device is provided.Below in conjunction with instantiation acquiring pseudo code device of the present invention is elaborated.

Embodiment 1: as shown in Figure 2, do not consider the carrier doppler search in the present embodiment, this situation is applicable to the application scenario that the carrier transmitting-receiving frequency departure is smaller.System receiving terminal uses M antenna, and the Direct Sequence Spread Spectrum Signal that each antenna receives through after the amplification of radio frequency unit process low noise, filtering, being converted to intermediate-freuqncy signal, is delivered to the acquisition equipment among Fig. 2 earlier.

Deliver to the signal of acquisition equipment and deliver to analog-to-digital conversion unit 100 earlier.The analog-to-digital conversion unit is made up of M analog-digital converter (ADC) 101, carries out sample quantization in the analog-to-digital conversion unit, so that carry out the digitized processing in later stage.

In Digital Down Convert unit 110, the carrier signal that received signal behind the sample quantization and carrier generator 111 produce multiplies each other, and realizes down-conversion, obtains digital baseband signal.Obtain array sampling snap in the observation time N time, the vector form of the i time fast beat of data is

x(i)＝[x ₁(i)，x ₂(i)，…，x _M(i)] ^T (8)

Here () ^TThe computing of expression transposition, i=1 ... N is the numbering of sampling instant and data, and with this as time reference.

Digital baseband signal is delivered to correlator unit 120, calculates the relevant output that adds up with local pseudo-code.

In correlator unit, comprise M relevant accumulator 122.Here, the baseband sampling signal of each antennas paths and local pseudo-code generator produce 121 pseudo-code signal and carry out relevantly, and the relevant output of a plurality of branch roads constitutes an output vector y.

$y={\hat{r}}_{\mathrm{xd}}=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}x\left(i\right)d^{*}\left(i\right)---\left(9\right)$

Here, () * represents to grip altogether, and the pseudo-code that the local pseudo-code generator of d (i) expression produces is in the value of sampling instant i.

Digital baseband signal is also delivered to prize judgment statistic computing unit 130 simultaneously, is used for the computer memory correlation matrix.Prize judgment statistic computing unit comprises three partial circuits: spatial correlation matrix computing unit 131, spatial domain weight calculation unit 132, spatial domain weighted units 133.The processing procedure of this unit is:

1) determines spatial correlation matrix.

To piecemeal between the area of observation coverage, the data sampling point of each data block is K, and K is a little positive integer.If it is the integral multiple of K that observation detects N, then be divided into L=N/K data block between the area of observation coverage, each data block sampling point quantity is K.If N can not be divided exactly by L, be divided between the area of observation coverage Individual data block, here

Round operation in the expression, at this moment preceding L-1 section has K measured value for every section, and final stage has K measured value of N-(L-1).In each piece, the dateout of utilizing data in this data block and reference signal to carry out behind the part correlation is calculated correlation matrix.If N can be divided exactly by L, the dateout behind the part correlation can be expressed as

$x_1\left(i\right)=\frac{1}{K}\underset{j=1}{\overset{K}{\mathrm{\Σ}}}x((i-1)K+j)d^{*}((i-1)K+j),i=\mathrm{1,2},\·\·\·,L---\left(10a\right)$

If N can not be divided exactly by L, then the dateout behind the part correlation can be expressed as

$x_1\left(i\right)=\frac{1}{K}\underset{j=1}{\overset{K}{\mathrm{\Σ}}}x((i-1)K+j)d^{*}((i-1)K+j),i=\mathrm{1,2},\·\·\·,L-1$

$x_1\left(L\right)=\frac{1}{N-(L-1)K}\underset{j=N-(L-1)*K+1}{\overset{N}{\mathrm{\Σ}}}x\left(j\right)d^{*}\left(j\right)---\left(10b\right)$

Determine spatial correlation matrix according to following formula

${\hat{R}}_{x_1}=\frac{1}{L}\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{x}_1\left(i\right)x_1^H\left(i\right)---\left(11\right)$

2) determine the spatial domain weights

According to spatial correlation matrix

Export the adaptive weight that y obtains the spatial domain weighted with correlator unit:

$\hat{w}={\hat{R}}_{x_1}^{-1}y$

3) determine the decision statistic amount

$z={\hat{w}}^{H}y---\left(12\right)$

At thresholding comparing unit 140, decision statistic amount z, the decision threshold β that determines with thresholding setup unit 141 _TIn comparator 142, compare judgement.What use in the present embodiment is single search strategy that stops, if the decision statistic amount is greater than thresholding β _T, then change tracing process over to.If less than decision threshold β _T, then control local pseudo-code generator 121, change local pseudo-code with respect to the phase place that receives pseudo-code, calculate the decision statistic amount according to received signal again, carry out threshold judgement, up to realize catching change tracing process over to till.

Thresholding β _TRequire to determine according to system parameters and performance index.These parameters comprise the integration lengths of false alarm probability, antenna amount, sliding correlation detector etc., and in the present embodiment, false alarm probability can be obtained by following formula:

$P_F={\∫}_{{\mathrm{\β}}_T}^1\frac{1}{B(M,L-M)}{x}^{M-1}{(1-x)}^{L-M-1}\mathrm{dx}---\left(13\right)$

Here B () expression beta function.According to the false alarm probability of system requirements, the antenna amount that coupling system uses, observation detect length, number of fragments, can determine decision threshold β by numerical computations _TFor the canonical parameter of the many groups in the practical application, can calculate thresholding and storage in advance, from memory, read corresponding threshold value then and be used for prize judgment.

Embodiment 2: as shown in Figure 3, in the present embodiment, used the carrier doppler parallel search, this situation is applicable to the application scenario that the carrier transmitting-receiving frequency departure is bigger.System receiving terminal uses M antenna, and the Direct Sequence Spread Spectrum Signal that each antenna receives through after the amplification of radio frequency unit process low noise, filtering, being converted to intermediate-freuqncy signal, is delivered to the acquisition equipment among Fig. 2 earlier.

The signal of delivering to acquisition equipment carries out sample quantization, so that carry out the digitized processing in later stage earlier through analog-to-digital conversion unit 100.The digital signal of sample quantization is delivered to respectively in the P group capture component 200.In every group of capture component 200, all comprise Digital Down Convert unit 110, correlator unit 120, prize judgment statistic computing unit 130.In the present embodiment, each carrier generator 111 in the P group capture component 200 all produces has a plurality of carrier frequencies of certain difference to be used for down-conversion, obtain digital baseband signal, identical among the basic composition of these unit and the embodiment 1 in addition, therefore be not described in detail here.Every group of capture component 200 all exported a decision statistic amount, delivers to maximum selected cell 300, selects a wherein maximum z _mDeliver to thresholding comparing unit 140.

In thresholding comparing unit 140, decision statistic amount z _mWith decision threshold β _TCompare judgement.Identical among definite method of the thresholding in the present embodiment and the embodiment 1.What use in the present embodiment is single search strategy that stops, if the decision statistic amount is greater than thresholding β _T, then change tracing process over to.If less than decision threshold β _T, then control local pseudo-code generator 121, change local pseudo-code with respect to the phase place that receives pseudo-code, calculate the decision statistic amount according to received signal again, carry out threshold judgement, up to realize catching change tracing process over to till.

The above only is a preferred implementation of the present invention, and protection scope of the present invention also not only is confined to the foregoing description, and all technical schemes that belongs under the thinking of the present invention all belong to protection scope of the present invention.Should be pointed out that for those skilled in the art in the some improvements and modifications that do not break away under the principle of the invention prerequisite, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (10)

1. a Resistant DS Spread Spectrum System is used the method for acquiring pseudo code of many antennas, it is characterized in that step is:

1., each antenna uses one and catches branch road, obtains the spatial correlation matrix of received signal according to each antenna receiving signal, in conjunction with catching the definite adaptive weight vector of branch road output;

2., the adaptive weight vector that uses above-mentioned steps to obtain in 1. is weighted summation to catching branch road output, output is as the statistic of prize judgment;

3., the statistic of prize judgment that above-mentioned steps is obtained in 2. and thresholding compare and make judgement, if the statistic of prize judgment greater than thresholding, then changes tracking phase over to; Otherwise conversion is caught local PN sign indicating number in the branch road with respect to the PN code phase of received signal, repeats said process.

2. Resistant DS Spread Spectrum System according to claim 1 is used the method for acquiring pseudo code of many antennas, it is characterized in that described step idiographic flow 1. is:

I, the sampling of obtaining the baseband signal of each bay received signal;

II, each array element baseband sampling signal are caught branch road by one, obtain the relevant output with local pseudo-code signal, and the relevant output of a plurality of branch roads constitutes an output vector

Wherein () ^*Expression is gripped altogether, X=[x (1), and x (2) ..., x (N)] and the signal matrix formed by the array received signal vector between the area of observation coverage, d=[d (1), d (2) ..., d (N)] ^TIt is reference signal vector, d (i)=c (i-Δ τ), c (i) expression received signal PN sign indicating number is in the value of sampling instant i, Δ τ is the phase difference that receives PN sign indicating number and local PN sign indicating number, Δ τ=0 when the PN sign indicating number is synchronous, y is that the array received signal between the area of observation coverage carries out relevant output with reference signal, i.e. output vector after the despreading computing;

Obtain spatial correlation matrix after III, the signal process part correlation computing according to receiving array, described spatial correlation matrix is determined by following formula

X wherein ₁(i), i=1 ..., L determines according to following process: to piecemeal between the area of observation coverage, the data sampling point of each data block is K, and K is a little positive integer; If it is the integral multiple of K that observation detects N, then be divided into L=N/K data block between the area of observation coverage, each data block sampling point quantity is K; If N can not be divided exactly by L, be divided between the area of observation coverage

Individual data block, here

Round operation in the expression, at this moment preceding L-1 section has K measured value for every section, and final stage has K measured value of N-(L-1); In each piece, the dateout of utilizing data in this data block and reference signal to carry out behind the part correlation is calculated correlation matrix; If N can be divided exactly by L, the dateout behind the part correlation is

I=1,2 ..., L; If N can not be divided exactly by L, then the dateout behind the part correlation can be expressed as

I=1,2 ..., L-1,

IV, calculate the adaptive array weights in conjunction with spatial correlation matrix and a plurality of output vector of catching branch road

3. Resistant DS Spread Spectrum System according to claim 1 and 2 is used the method for acquiring pseudo code of many antennas, it is characterized in that: described thresholding is determined according to the integration lengths of false alarm probability, antenna amount, sliding correlation detector.

4. Resistant DS Spread Spectrum System according to claim 3 is used the method for acquiring pseudo code of many antennas, it is characterized in that: described false alarm probability is

Here B () expression Beta function, β _TBe threshold value.

5. a Resistant DS Spread Spectrum System is used the acquiring pseudo code device of many antennas, it is characterized in that, comprising:

Analog-to-digital conversion unit (100) is used for receiving the Direct Sequence Spread Spectrum Signal after radio frequency unit is handled that each antenna is sent here, and this signal is carried out sample quantization;

Digital Down Convert unit (110) receives the received signal behind the sample quantization that transmits through analog-to-digital conversion unit (100), carries out down-conversion and obtains digital baseband signal;

Correlator unit (120) receives the digital baseband signal that transmits through Digital Down Convert unit (110), and this digital baseband signal and local pseudo-code are carried out the relevant back output that adds up;

Prize judgment statistic computing unit (130) receives the digital baseband signal that transmits through Digital Down Convert unit (110), obtains spatial correlation matrix, and determines spatial domain weights and decision statistic amount according to the output of spatial correlation matrix and correlator unit (120);

Thresholding comparing unit (140) is preset with decision threshold, and decision statistic amount and decision threshold are compared judgement, if the decision statistic amount greater than decision threshold, then changes tracing process over to; If the decision statistic amount, then changes local pseudo-code less than decision threshold with respect to the phase place that receives pseudo-code, calculate the decision statistic amount according to received signal again, carry out threshold judgement, up to realize catching change tracing process over to till.

6. Resistant DS Spread Spectrum System according to claim 5 is used the acquiring pseudo code device of many antennas, it is characterized in that: described prize judgment statistic computing unit (130) comprises spatial correlation matrix computing unit (131), spatial domain weight calculation unit (132) and spatial domain weighted units (133).

7. use the acquiring pseudo code device of many antennas according to claim 5 or 6 described Resistant DS Spread Spectrum System, it is characterized in that: described Digital Down Convert unit (110) comprises carrier generator (111), the carrier signal that received signal behind the sample quantization that transmits through analog-to-digital conversion unit (100) and described carrier generator (111) the produce realization down-conversion that multiplies each other obtains digital baseband signal.

8. a Resistant DS Spread Spectrum System is used the acquiring pseudo code device of many antennas, it is characterized in that, comprising:

Analog-to-digital conversion unit (100) is used for receiving the Direct Sequence Spread Spectrum Signal after radio frequency unit is handled that each antenna is sent here, and this signal is carried out delivering to respectively behind the sample quantization in the capture component (200) more than one group;

Described every group of capture component (200) includes Digital Down Convert unit (110), correlator unit (120), prize judgment statistic computing unit (130); Described Digital Down Convert unit (110) receives the received signal behind the sample quantization that transmits through analog-to-digital conversion unit (100), carries out down-conversion and obtains digital baseband signal; Described correlator unit (120) receives the digital baseband signal that transmits through Digital Down Convert unit (110), and this digital baseband signal and local pseudo-code are carried out the relevant output that adds up; Described prize judgment statistic computing unit (130), the digital baseband signal that reception is transmitted through Digital Down Convert unit (110), obtain spatial correlation matrix, and determine spatial domain weights and decision statistic amount according to the output of spatial correlation matrix and correlator unit (120);

Maximum selected cell (300) receives the decision statistic amount that each group capture component (200) is exported, and selects one of maximum to deliver to thresholding comparing unit (140);

Thresholding comparing unit (140) is preset with decision threshold, and decision statistic amount and decision threshold are compared judgement, if the decision statistic amount greater than decision threshold, then changes tracing process over to; If the decision statistic amount, then changes local pseudo-code less than decision threshold with respect to the phase place that receives pseudo-code, calculate the decision statistic amount according to received signal again, carry out threshold judgement, up to realize catching change tracing process over to till.

9. Resistant DS Spread Spectrum System according to claim 8 is used the acquiring pseudo code device of many antennas, it is characterized in that: described prize judgment statistic computing unit (130) comprises spatial correlation matrix computing unit (131), spatial domain weight calculation unit (132) and spatial domain weighted units (133).

According to Claim 8 or 9 described Resistant DS Spread Spectrum System use the acquiring pseudo code device of many antennas, it is characterized in that: described Digital Down Convert unit (110) comprises carrier generator (111), the carrier signal that received signal behind the sample quantization that transmits through analog-to-digital conversion unit (100) and described carrier generator (111) the produce realization down-conversion that multiplies each other obtains digital baseband signal.

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