CN105204036A - Tracking loop design method based on multi-path inhibiting signals - Google Patents

Abstract

The invention relates to a method for reducing errors in the message demodulation and navigation process, in particular to a tracking loop design method based on multi-path inhibiting signals. The method comprises the following steps that a satellite navigation signal received through an antenna of a navigation receiver is given, digital down conversion is conducted on the satellite navigation signal received through the navigation receiver, an intermediate frequency signal is obtained, quantification is conducted on the intermediate frequency signal, and a quantification signal is obtained; the quantification signal passes through a filter, autocorrecting computing is conducted on the quantification signal, and a sequence input to an equalizer can be obtained; after the intermediate frequency signal is captured through the navigation receiver, the intermediate frequency signal conducts computing with an I by-pass carrier wave and a Q by-pass carrier wave which are output through a carrier-tracking loop, and carrier wave stripping is completed; the intermediate frequency signal which is subjected to carrier wave stripping conducts channel compensation by means of the equalizer which is input with the sequence, interrelated tracking is conducted on a code tracking loop and the carrier-tracking loop, and message demodulation and navigation are achieved. By means of the tracking loop design method, the tracking effect of a navigation machine is more accurate, and the positioning accuracy is improved.

Description

A kind of track loop method for designing based on suppressing multipath signal

Technical field

The present invention relates to the method reducing error in demodulation navigation message process, being specially a kind of track loop method for designing based on suppressing multipath signal.

Background technology

As one of information industry with fastest developing speed, satellite navigation industry is more and more subject to the attention of country.Satellite navigation signals, as a kind of information resources shared for hundreds of thousands of subscribers, for vast user, needs to determine that the satellite receiver of locating information is caught, track navigation satellite-signal.Therefore, navigation neceiver plays vital effect positioning in the process resolved.

Can draw from current research, multipath effect has become the main source of error that navigation neceiver is measured, its there is the difficult problem of time variation and environmental characteristics.The harm of multipath effect, first can make to be modulated to the ranging code on navigation signal and navigation data distortion, but also the phase place of carrier wave can be caused to distort; The quality that also can affect each measurement data reduces; Situation the most serious is, multipath signal can cause the loop losing lock of receiver.

Summary of the invention

The problem of error can be there is in the present invention under multipath signal interference to solve navigation neceiver track loop, provide one and take balancing technique in track loop, its equalizer coefficients upgrades a kind of track loop method for designing based on suppressing multipath signal taked based on CMA algorithm.

The present invention adopts following technical scheme to realize: a kind of track loop method for designing based on suppressing multipath signal, comprises the following steps:

The satellite navigation signals s that given navigation neceiver antenna receives ⁽ⁱ⁾(t), in formula, i represents the numbering of satellite, and subscript I, Q are respectively two branch roads, and A represents signal amplitude, and C represents ranging code, and D represents the numeric data code that pseudo-code is modulated, f ₀represent carrier frequency, represent the initial phase of carrier wave, N'(t) represent noise signal;

Satellite navigation signals s ⁽ⁱ⁾t () obtains intermediate-freuqncy signal s after Digital Down Convert ⁽ⁱ⁾' (t), ${s^{\left(i\right)}}^{\′}\left(t\right)=\underset{i=0}{\overset{N}{\mathrm{\Σ}}}{\∂}_{i}AC(t-{\mathrm{\τ}}_i)D(t-{\mathrm{\τ}}_i)cos\[2\mathrm{\π}\left(f_{IF}+f_d\right)t+{\mathrm{\φ}}_i\]+N^{\′}\left(t\right),$ In formula, i=0 represents satellite direct signal, and i ≠ 0 represents the multipath signal on other roads, and N is the quantity of multipath signal, and A represents signal amplitude, represent signal amplitude fading coefficients, D (t) represents the numeric data code of navigation message, and C (t) represents C/A code, τ _irepresent chip delay, f _iFrepresent the frequency of intermediate-freuqncy signal, f _drepresent Doppler frequency deviation, represent i-th signal phase, N'(t) represent noise signal;

To intermediate-freuqncy signal s ⁽ⁱ⁾' (t) carry out quantification and obtain quantized signal s [n], t in formula _sfor sampling interval;

Quantized signal s [n] device and auto-correlation computation after filtering, can obtain the sequence W (n+1) of input equalizer, carry out signal equalization on this basis, W (n+1) iterative formula is as follows:

$W(n+1)=W\left(n\right)-\mathrm{\α}f\left(n\right)z\left(n\right)\[z{\left(n\right)}^2-\left|\hat{a}\right(n){|}^2\]X^{*}\left(n\right),$

$f\left(n\right)=\left\{\begin{array}{cc}1,& \mathrm{sgn}\[z{\left(n\right)}^2-{\left|\widehat{\mathrm{\α}}\left(n\right)\right|}^2\]=\mathrm{sgn}\[z{\left(n\right)}^2-R\]\\ 0,& \mathrm{sgn}\[z{\left(n\right)}^2-{\left|\widehat{\mathrm{\α}\left(n\right)}\right|}^2\]\≠\mathrm{sgn}\[z{\left(n\right)}^2-R\]\end{array}\right.;$ W (n+1) represents the equalized sequence in n+1 moment, and W (n) represents the equalized sequence in n moment, and α represents equalizing coefficient, and z (n) represents the signal quantization sequence in n moment, represent the modulus value of the signal quantization sequence in n moment, X ^*n () represents satellite-signal, R represents threshold value;

Navigation neceiver completes after intermediate-freuqncy signal catches, and intermediate-freuqncy signal enters track loop and starts working, and the I branch road carrier wave that intermediate-freuqncy signal exports with carrier tracking loop respectively and Q branch road carrier wave carry out computing respectively, complete stripping carrier wave;

Complete and peel off the intermediate-freuqncy signal of carrier wave and utilize input to have the balanced device of sequence W (n+1) to carry out channel compensation, finally enter code tracking loop respectively and carrier tracking loop carries out correlation tracking, realize demodulation navigation message.

This loop effectively can weaken multipath effect, when there is multi-path jamming in channel, introduce the tracking accuracy of code tracking precision higher than typical early slow DLL loop of this equalization algorithm in track loop, thus improve the measuring accuracy of pseudorange, and then the positioning precision of navigation neceiver can be improved.

Accompanying drawing explanation

The classical code tracking loop block diagram of Fig. 1.

The classical carrier tracking loop block diagram of Fig. 2.

Fig. 3 is inventive receiver track loop block diagram.

Embodiment

Based on the track loop method for designing suppressing multipath signal, comprise the following steps:

The satellite navigation signals s that given navigation neceiver antenna receives ⁽ⁱ⁾(t), in formula, i represents the numbering of satellite, and subscript I, Q are respectively two branch roads, and A represents signal amplitude, and C represents ranging code, and D represents the numeric data code that pseudo-code is modulated, f ₀represent carrier frequency, represent the initial phase of carrier wave, N'(t) represent noise signal;

The satellite navigation signals s of the civil navigation receiver reception of single-frequency ⁽ⁱ⁾t () obtains intermediate-freuqncy signal s after Digital Down Convert ⁽ⁱ⁾' (t), ${s^{\left(i\right)}}^{\′}\left(t\right)=\underset{i=0}{\overset{N}{\mathrm{\Σ}}}{\∂}_{i}AC(t-{\mathrm{\τ}}_i)D(t-{\mathrm{\τ}}_i)cos\[2\mathrm{\π}\left(f_{IF}+f_d\right)t+{\mathrm{\φ}}_i\]+N^{\′}\left(t\right),$ In formula, i=0 represents satellite direct signal, and i ≠ 0 represents the multipath signal on other roads, and N is the quantity of multipath signal, and A represents signal amplitude, represent signal amplitude fading coefficients, D (t) represents the numeric data code of navigation message, and C (t) represents C/A code, τ _irepresent chip delay, f _iFrepresent the frequency of intermediate-freuqncy signal, f _drepresent Doppler frequency deviation, represent i-th signal phase, N'(t) represent noise signal;

To intermediate-freuqncy signal s ⁽ⁱ⁾' (t) carry out quantification and obtain quantized signal s [n], t in formula _sfor sampling interval;

Quantized signal s [n] device and auto-correlation computation after filtering, can obtain the sequence W (n+1) of input equalizer, carry out signal equalization on this basis, W (n+1) iterative formula is as follows:

$W(n+1)=W\left(n\right)-\mathrm{\α}f\left(n\right)z\left(n\right)\[z{\left(n\right)}^2-\left|\hat{a}\right(n){|}^2\]X^{*}\left(n\right),$

$f\left(n\right)=\left\{\begin{array}{cc}1,& \mathrm{sgn}\[z{\left(n\right)}^2-{\left|\widehat{\mathrm{\α}}\left(n\right)\right|}^2\]=\mathrm{sgn}\[z{\left(n\right)}^2-R\]\\ 0,& \mathrm{sgn}\[z{\left(n\right)}^2-{\left|\widehat{\mathrm{\α}\left(n\right)}\right|}^2\]\≠\mathrm{sgn}\[z{\left(n\right)}^2-R\]\end{array}\right.;$ W (n+1) represents the equalized sequence in n+1 moment, and W (n) represents the equalized sequence in n moment, _αrepresent equalizing coefficient, z (n) represents the signal quantization sequence in n moment, represent the modulus value of the signal quantization sequence in n moment, X ^*n () represents satellite-signal, R represents threshold value;

Navigation neceiver completes after intermediate-freuqncy signal catches, and intermediate-freuqncy signal enters track loop and starts working, and the I branch road carrier wave that intermediate-freuqncy signal exports with carrier tracking loop respectively and Q branch road carrier wave carry out computing respectively, complete stripping carrier wave;

Complete and peel off the intermediate-freuqncy signal of carrier wave and utilize input to have the balanced device of sequence W (n+1) to carry out channel compensation, finally enter code tracking loop respectively and carrier tracking loop carries out correlation tracking, realize demodulation navigation message.

Claims (1)

1., based on the track loop method for designing suppressing multipath signal, it is characterized in that comprising the following steps:

The satellite navigation signals s that given navigation neceiver antenna receives ⁽ⁱ⁾(t),

in formula, i represents the numbering of satellite, and subscript I, Q are respectively two branch roads, and A represents signal amplitude, and C represents ranging code, and D represents the numeric data code that pseudo-code is modulated, f ₀represent carrier frequency, represent the initial phase of carrier wave, N'(t) represent noise signal;

Satellite navigation signals s ⁽ⁱ⁾t () obtains intermediate-freuqncy signal s after Digital Down Convert ⁽ⁱ⁾' (t),

$S^{\left(i\right)}\′\left(t\right)=\underset{i=0}{\overset{N}{\Σ}}{\∂}_{i}AC(t-{\mathrm{\τ}}_i)D(t-{\mathrm{\τ}}_i)cos\[2\mathrm{\π}(f_{IF}+f_d)t+{\mathrm{\φ}}_i\]+N^{\′}\left(t\right),$ In formula, i=0 represents satellite direct signal, and i ≠ 0 represents the multipath signal on other roads, and N is the quantity of multipath signal, and A represents signal amplitude, represent signal amplitude fading coefficients, D (t) represents the numeric data code of navigation message, and C (t) represents C/A code, τ _irepresent chip delay, f _iFrepresent the frequency of intermediate-freuqncy signal, f _drepresent Doppler frequency deviation, represent i-th signal phase, N'(t) represent noise signal;

To intermediate-freuqncy signal s ⁽ⁱ⁾' (t) carry out quantification and obtain quantized signal s [n],

t in formula _sfor sampling interval;

Quantized signal s [n] device and auto-correlation computation after filtering, can obtain the sequence W (n+1) of input equalizer, carry out signal equalization on this basis, W (n+1) iterative formula is as follows:

$W(n+1)=W\left(n\right)-\mathrm{\α}f\left(n\right)z\left(n\right)\[z{\left(n\right)}^2-|\hat{a}\left(n\right){|}^2\]X^{*}\left(n\right),$

$f\left(n\right)=\left\{\begin{array}{cc}1,& \mathrm{sgn}\[z{\left(n\right)}^2-{\left|\widehat{\mathrm{\α}}\left(n\right)\right|}^2\]=\mathrm{sgn}\[z{\left(n\right)}^2-R\]\\ 0,& \mathrm{sgn}\[z{\left(n\right)}^2-{\left|\widehat{\mathrm{\α}\left(n\right)}\right|}^2\]\≠\mathrm{sgn}\[z{\left(n\right)}^2-R\]\end{array}\right.,$ W (n+1) represents the equalized sequence in n+1 moment, and W (n) represents the equalized sequence in n moment, and α represents equalizing coefficient, and z (n) represents the signal quantization sequence in n moment, represent the modulus value of the signal quantization sequence in n moment, X ^*n () represents satellite-signal, R represents threshold value;

Navigation neceiver completes after intermediate-freuqncy signal catches, and intermediate-freuqncy signal enters track loop and starts working, and the I branch road carrier wave that intermediate-freuqncy signal exports with carrier tracking loop respectively and Q branch road carrier wave carry out computing respectively, complete stripping carrier wave;

Complete and peel off the intermediate-freuqncy signal of carrier wave and utilize input to have the balanced device of sequence W (n+1) to carry out channel compensation, finally enter code tracking loop respectively and carrier tracking loop carries out correlation tracking, realize demodulation navigation message.