CN106443718A - Measurement zero value non-error tracking system and method based on correlation peak correction under non-ideal channel - Google Patents

Abstract

The invention provides a measurement zero value non-error tracking system and method based on correlation peak correction under a non-ideal channel. Based on the structure of an anti-interference filter, firstly a correlation peak obtained after interference suppression is factorized into a sum of a center correlation peak and a series of delay correlation peaks, then the correlation peak amplitude to be input into a tracking loop is estimated by means of the least square method, and finally according to the known order, coefficient and first sampling test information of an interference suppression filter, the components of the delay correlation peaks are deducted from a final composed correlation peak so that the shape of the correlation peak input into an early-delay ring is consistent with that of the correlation peak obtained before interference suppression. The method solves the problem that under non-ideal channel, the measurement zero value of a traditional tracking channel is fluctuated with the changes of external interference is solved, and the project is very easy to achieve. The tracking system and method can be used in a satellite navigation receiver where anti-interference requirements and high precision distance measuring requirements need to be met at the same time.

Description

Measurement null value non-error tracking system under non-ideal communication channel based on relevant peaks correction and its Method

Technical field

The present invention relates to satellite navigation receiver design field, specifically a kind of satellite navigation receiver signal pseudo-code Tracking, which can be used in satellite navigation receiver design.

Background technology

In the operation of satellite navigation system and application process, satellite navigation receiver is one of its nucleus equipment.This In the satellite navigation receiver of indication not only include the miscellaneous receiver of User Part, also refer to space segment and above ground portion Receiver.The latter is mainly used in completing star ground, stand between the function such as precise synchronization, communication, typically than User Part Receiver has higher performance requirement, and for the system accuracy demand of nanosecond order, such receiver need to reach subnanosecond amount The range accuracy of level.When range accuracy brings up to magnitude of subnanosecond, the group delay characteristic of such as receiver channel, amplitude-frequency spy The factors such as property, the stability of time-frequency are all likely to result in measurement error.

Existing time domain anti-interference method is to assume channel characteristic ideally, by time domain anti-interference filtration Device parameter enters row constraint so that wave filter meets linear phase, constant to reach receiver measurement null value under any jamming pattern Purpose.But the distortion due to the analog device such as RF cable, amplifier and frequency mixer is caused in actual navigation neceiver In, its passage be typically difficult to meet in band amplitude-frequency response be constant value, group delay response for constant value (phase response is linear) reason Think condition.Receiver time delay can be caused to estimate to change so as to above-mentioned interference protection measure, and variable quantity and interference immunity parameter Related.

Content of the invention

For the problem that prior art is present, technical scheme is proposed based on correlation under a kind of non-ideal communication channel The measurement null value non-error tracking system and method for peak correction, interference is pressed down first by which from the structure of anti-interference filter Centered on relevant peaks decomposition after system, relevant peaks and a series of delay relevant peaks sums, recycle method of least square to estimate input To the related peak-to-peak amplitude of track loop, finally according to known interference suppression filter exponent number, coefficient and sample rate prior information, Deduct from the relevant peaks of final synthesis and postpone relevant peaks component, so that being input into the early correlation peak shape of ring and interference late Correlation peak shape before suppression is consistent.This method solving traditional tracking channel null value is measured under non-ideal communication channel with outside Interference variations and the problem that fluctuates, and Project Realization is very simple.

The technical scheme is that：

A kind of measurement null value non-error tracking system under non-ideal communication channel based on relevant peaks correction, including anti-interference filtration Device, correlator, local puppet code generator, long-time statistical average module, amplitude Estimation module, relevant peaks correcting module, code with Track loop, wherein long-time statistical average module, amplitude Estimation module, relevant peaks correcting module are the distinctive invention of this patent, Remaining module is identical with traditional GNSS receiver；

Anti-interference filter adopts the horizontal anti-interference filter of time domain two-tap, narrow in the baseband signal being input into by estimating Band interference signal, the narrow-band interference signal for removing in the baseband signal of input retains GNSS broadband useful signal；

The signal input correlator of anti-interference rejects trap output, correlator is local by local puppet code generator generation The baseband signal that pseudo-code signal is exported with anti-interference rejects trap carries out related operation, obtains the correlation comprising white Gaussian noise Peak R (τ)；

When long-time statistical average module carried out long by the relevant peaks obtained by correlator before system starts Between statistical average, obtain the benchmark relevant peaks after normalization not comprising noise

Amplitude Estimation module estimates the related peak amplitude not comprising noise by maximal possibility estimation criterion

The related peak amplitude that relevant peaks correcting module is estimated using amplitude Estimation module is modified simultaneously to relevant peaks main lobe Revised relevant peaks are sent into track loop；

The pseudo-code phase of code tracking loop tracking input GNSS signal, obtains being input into GNSS signal with local puppet code generator The amount of phase error Δ τ of the pseudo-code signal of generation；

The amount of phase error Δ τ of the pseudo-code signal that local puppet code generator is fed back according to code tracking loop is generated and input GNSS The consistent local pseudo-code signal of broadband useful signal pseudo-code phase.

Based on said system, the present invention also provides the measurement null value unbiased under a kind of non-ideal communication channel based on relevant peaks correction Tracking, comprises the following steps：

S1. GNSS base band signal x (n) being input into first passes around the horizontal anti-interference filter of time domain two-tap, time domain The horizontal anti-interference filter of two-tap presses transversely arranged delay cell Z by 2M^-1And tap coefficient h (i) is constituted, tap is spaced Equal to sampling interval T_s, after the postpones signal of each tap sends into an added circuit after being multiplied with corresponding tap coefficient h (i) Output.As shown in figure 1, signal y (n) after anti-interference filter is：

Wherein：H (i) is the coefficient of horizontal i-th tap of anti-interference filter of time domain two-tap, T_sFor the sampling period.

S2. signal y (n) of anti-interference filter output is carried out related operation with local pseudo-code and obtains the phase comprising noise Closing peak main lobe R (τ) is：

Wherein：

L=ceil (2T_c/T_s)

Ceil () is the function that rounds up, and r (τ) is the original correlation after related to local pseudo-code of input signal x (n) Peak, n is white Gaussian noise, T_cFor chip period, T_sFor the sampling period.

S3. relevant peaks main lobe R (τ) is through relevant peaks correcting module, revised relevant peaks main lobeFor：

WhereinFor normalized benchmark relevant peaks, by the coefficient of interference suppression filter is set to：H (i)=0, I ≠ 0, h (0)=1, relevant peaks are carried out with long-time statistical average, the normalized benchmark relevant peaks not comprising noise are obtained, should Process and can realize offline.For the related peak amplitude not comprising noise that estimates.The amplitude of relevant peaks is obtained by amplitude Estimation module Arrive, amplitude Estimation module obtains the relevant peaks Amplitude Estimation amount not comprising noise using maximal possibility estimation criterion

S4. revised relevant peaks main lobeCode tracking loop is sent into, code tracking loop calculates phase place by mistake by following formula Residual quantity Δ τ：

Wherein：D is spaced late for early, usually T_c/ 2, k are proportionality coefficient.

Description of the drawings

The schematic diagram of the horizontal anti-interference filter of time domain two-tap used in Fig. 1 present invention.

Fig. 2 present invention realizes structural representation.

Specific embodiment

Fig. 1 is the horizontal anti-interference filter of time domain two-tap used in the present invention, the i.e. wave filter of interpositioning.Black soy sauce Head transversal filter presses transversely arranged delay cell Z by 2M^-1And tap coefficient h (i) is constituted, tap is spaced equal between sampling Every T_s, the postpones signal of each tap be multiplied with corresponding tap coefficient h (i) after send into an added circuit after export.It is same When make use of data in the past and the data in future, x is estimated according to data set { x (n-M) ... x (n-1) x (n+1) ... x (n+M) } (n).

Based on the basic thought of the Narrow Band Interference Suppression Technique of Interference Estimation be using narrow band signal and broadband signal can Difference on evaluation characteristic, obtains the duplication of arrowband interference, then eliminates the interference signal of duplication again from reception signal, so as to Reach the purpose of suppression arrowband interference.Because arrowband interference is coloured noise, between sample value, there is very strong dependency, can be from past sample Value estimates current sample；And Direct Sequence Spread Spectrum Signal spectral flatness, almost uncorrelated between the sample value that general rate is sampled to cut.When When including wide band direct sequence spread-spectrum signal component and arrowband interference components in reception signal, if generating a reception simultaneously The estimated value of signal, then by the estimation mainly to narrow-band interference signal in estimated value.Before despreading from reception signal The estimated value is deducted, the arrowband interference components for receiving in signal will be substantially reduced, so as to greatly improve Resistant DS Spread Spectrum System Capacity of resisting disturbance.

Through signal y (n) of the horizontal anti-interference filter output of time domain two-tap it is：

Wherein h (i) is the coefficient of horizontal i-th tap of anti-interference filter of time domain two-tap：

The coefficient vector w of the coefficient of horizontal i-th tap of anti-interference filter of time domain two-tap is generally (minimum using MMSE Mean square error) criterion obtain as follows：

If input signal x (n) is：

X (n)=s (n)+j (n)

Wherein s (n) is useful signal, and j (n) is interference signal.

It is J then to define cost function：

J=E [y (n) y^*(n)]

Wherein y (n) is error signal, y^*N () is expectation function for its conjugate transpose vector, E [],：

Y (n)=s (n)-w^Hx(n)

Wherein w^HFor the complex conjugate transposed vector of coefficient vector w, then the horizontal anti-interference filter of time domain two-tap is taken out for i-th The coefficient vector w of coefficient of head is：

Wherein：R_xxFor the autocorrelation matrix of input signal, r_xsFor useful signal and the dependent vector for receiving signal：

r_xs=E [x (n) s^*(n)]

Fig. 2 is the realization of the measurement null value non-error tracking system under a kind of non-ideal communication channel of the present invention based on relevant peaks correction The interference signal that structural representation, wherein anti-interference filter are used for removing in input signal retains useful signal；Correlator will The baseband signal that local pseudo-code is exported with anti-interference filter carries out related operation；Local puppet code generator is anti-according to track loop The margin of error of feedback generates the pseudo-code signal consistent with input signal phase place；Track loop passes through to track input signal pseudo-code phase, Above-mentioned part is consistent with traditional receiver.Compared to traditional receiver structure, measurement null value unbiased under non-ideal communication channel The core of tracking is the increase in amplitude Estimation and relevant peaks correcting module, and needs to obtain using long-time offline mode With reference to relevant peaks.Wherein related peak amplitude of the amplitude Estimation module by Least Square Method after anti-interference filter, Relevant peaks correcting module is modified to relevant peaks main lobe using the amplitude that estimates and revised relevant peaks is sent into tracking ring Road.

With reference to specific embodiment, the measurement null value based on relevant peaks correction under a kind of non-ideal communication channel of the present invention is described The implementation of non-error tracking method.

With sample frequency as 40MHz, pseudo-code code rate selection 10.23MHz, signal intermediate frequency frequency is 13.299MHz, and be concerned with product It is 10ms between timesharing, does not consider non-coherent integration, carrier-to-noise ratio is 35dBHz.Interference scene is as shown in the table：

The exponent number of the horizontal anti-interference filter of time domain two-tap is 25 ranks, and the complex coefficient for being obtained using MMSE criterion is：

h_i(i=-12 ... 0 ... 12)=[- 0.0447-0.0094i, -0.0452+0.0510i, -0.0464+ 0.0755i,-0.0524+0.0104i,-0.0127-0.0698i,0.0379-0.1280i,0.0486-0.1042i,0.0107- 0.0391i,-0.0457+0.0048i,-0.0554+0.0027i,0.0045-0.0226i,0.0992-0.0224i,1.0000, 0.0992+0.0224i,0.0045+0.0226i,-0.0554-0.0027i,-0.0457-0.0048i,0.0107+0.0391i, 0.0486+0.1042i,0.0379+0.1280i,-0.0127+0.0698i,-0.0524-0.0104i,-0.0464- 0.0755i,-0.0452-0.0510i,-0.0447+0.0094i]；

Make the related peak-to-peak amplitude after normalization for 1, then the related peak-to-peak amplitude that estimates is：0.8222；

Then revised signal relevant peaks are：

In sum, although the present invention is disclosed above with preferred embodiment, so which is not limited to the present invention, any Those of ordinary skill in the art, without departing from the spirit and scope of the present invention, when can make various change with retouching, therefore this Bright protection domain is defined when the scope for defining depending on claims.

Claims (5)

1. the measurement null value non-error tracking system under a kind of non-ideal communication channel based on relevant peaks correction, it is characterised in that：Including anti- Interference filter, correlator, local puppet code generator, long-time statistical average module, amplitude Estimation module, relevant peaks correction mould Block and code tracking loop,

Anti-interference filter adopts the horizontal anti-interference filter of time domain two-tap, by estimating that in the baseband signal being input into, arrowband is done Signal is disturbed, the narrow-band interference signal for removing in the baseband signal of input retains GNSS broadband useful signal；

The signal input correlator of anti-interference rejects trap output, the local pseudo-code that local puppet code generator is generated by correlator The baseband signal that signal is exported with anti-interference rejects trap carries out related operation, obtains relevant peaks R comprising white Gaussian noise (τ)；

Long-time statistical average module carried out long-time system by the relevant peaks obtained by correlator before system starts Meter is average, obtains the benchmark relevant peaks after the normalization not comprising noise

Amplitude Estimation module estimates the related peak amplitude not comprising noise by maximal possibility estimation criterion

The related peak amplitude that relevant peaks correcting module is estimated using amplitude Estimation module is modified to relevant peaks main lobe and will repair Relevant peaks after just send into track loop；

The pseudo-code phase of code tracking loop tracking input GNSS signal, obtains being input into GNSS signal with local puppet code generator generation Pseudo-code signal amount of phase error Δ τ；

The amount of phase error Δ τ of the pseudo-code signal that local puppet code generator is fed back according to code tracking loop is generated and input GNSS broadband The consistent local pseudo-code signal of useful signal pseudo-code phase.

2. the measurement null value non-error tracking system under non-ideal communication channel according to claim 1 based on relevant peaks correction, its It is characterised by：The anti-interference rejects trap adopts the horizontal anti-interference filter of time domain two-tap.

3. the measurement null value non-error tracking system under non-ideal communication channel according to claim 2 based on relevant peaks correction, its It is characterised by：The horizontal anti-interference filter of the time domain two-tap presses transversely arranged delay cell Z by 2M^-1And tap coefficient H (i) is constituted, and tap is spaced equal to sampling interval T_s, after the postpones signal of each tap is multiplied with corresponding tap coefficient h (i) Export after sending into an added circuit.

4. a kind of measurement null value non-error tracking method under non-ideal communication channel based on relevant peaks correction, it is characterised in that include with Lower step：

S1. GNSS base band signal x (n) being input into first passes around the horizontal anti-interference filter of time domain two-tap, the time domain The horizontal anti-interference filter of two-tap presses transversely arranged delay cell Z by 2M^-1And tap coefficient h (i) is constituted, tap is spaced Equal to sampling interval T_s, after the postpones signal of each tap sends into an added circuit after being multiplied with corresponding tap coefficient h (i) Output；

Signal y (n) after anti-interference filter is：

$y\left(n\right)=x\left(n\right)-\underset{i\≠0}{\overset{M}{\underset{i=-M}{\mathrm{\Σ}}}}h\left(i\right)x(n-{\mathrm{iT}}_s)$

Wherein：H (i) is the coefficient of horizontal i-th tap of anti-interference filter of time domain two-tap, T_sFor the sampling period；

S2. signal y (n) of anti-interference filter output is carried out related operation with local pseudo-code and obtains the relevant peaks comprising noise Main lobe R (τ) is：

$R\left(\mathrm{\τ}\right)=\underset{i=-L}{\overset{L}{\mathrm{\Σ}}}h\left(i\right)r(\mathrm{\τ}-{\mathrm{iT}}_s)+n$

Wherein：

L=ceil (2T_c/T_s)

Ceil () is the function that rounds up, and r (τ) for the original relevant peaks after related to local pseudo-code of input signal x (n), n is White Gaussian noise, T_cFor chip period, T_sFor the sampling period；

S3. relevant peaks main lobe R (τ) is through relevant peaks correcting module, revised relevant peaks main lobeFor：

$\tilde{R}\left(\mathrm{\τ}\right)=R\left(\mathrm{\τ}\right)-\hat{a}\·\underset{i=-L}{\overset{L}{\mathrm{\Σ}}}h\left(i\right)\stackrel{\‾}{R}(\mathrm{\τ}-{\mathrm{iT}}_s),i\≠0$

WhereinFor normalized benchmark relevant peaks, by the coefficient of interference suppression filter is set to：H (i)=0, i ≠ 0, Relevant peaks are carried out long-time statistical average by h (0)=1, obtain the normalized benchmark relevant peaks not comprising noise, the process Can realize offline；For the related peak amplitude not comprising noise that estimates；

S4. revised relevant peaks main lobeCode tracking loop is sent into, code tracking loop calculates amount of phase error by following formula Δτ：

$\mathrm{\Δ\τ}=\frac{k}{2}\frac{\tilde{R}\left(d\right)-\tilde{R}(-d)}{\tilde{R}\left(d\right)+\tilde{R}(-d)}$

Wherein：D is spaced late for early, usually T_c/ 2, k are proportionality coefficient.

5. the measurement null value non-error tracking method under non-ideal communication channel according to claim 4 based on relevant peaks correction, its It is characterised by, in step S3, the amplitude of correlation function is obtained by amplitude Estimation module, and amplitude Estimation module adopts maximum likelihood Estimation criterion obtains the estimator of related peak-to-peak amplitude

$\hat{a}=\frac{R(\mathrm{\τ}=0)}{\underset{i=-L}{\overset{L}{\Σ}}h\left(i\right)\stackrel{\‾}{R}\left({\mathrm{iT}}_s\right)}.$