CN104345323A - GPS satellite signal carrier loop tracking method and device - Google Patents

Abstract

The invention belongs to the wireless communication field and provides a GPS satellite signal carrier loop tracking method and device. The method includes the following steps that: the carrier to noise ratio of satellite signals is obtained; when the carrier to noise ratio of the satellite signals is greater than or equal to a first threshold value, a carrier loop tracks the satellite signals through adopting a frequency locked loop aided phase locked loop algorithm, wherein the carrier loop includes a frequency discriminator, a phase discriminator, a loop filter and a voltage controlled oscillator; and when the carrier to noise of the satellite signals is smaller than the first threshold value, a carrier loop tracks the signals through adopting a kalman filtering algorithm and the frequency locked loop aided phase locked loop algorithm in a combined manner, wherein the carrier loop includes a frequency discriminator, a phase discriminator, a kalman filter and a voltage controlled oscillator. With the GPS satellite signal carrier loop tracking method and device of the invention adopted, the working modes of the carrier loop can be dynamically adjusted according to the carrier to noise ratio of the satellite signals, and sensitivity and dynamic performance of tracking can be improved, and weak satellite signals can be better tracked when the dynamic performance is high.

Description

A kind of gps satellite signal carrier wave ring tracking and device

Technical field

The invention belongs to wireless communication field, particularly relate to a kind of gps satellite signal carrier wave ring tracking and device.

Background technology

GPS (G1oba1Positioning System, GPS) be the Global Positioning System (GPS) that the U.S. sets up, obtain more and more wider application in recent years, it can provide round-the-clock in global range, three-dimensional localization and the information that tests the speed accurately and reliably, obtained in aviation, navigation and land vehicle navigation and applied more and more widely, its effect has almost penetrated into the every field of society.

As long as general receiver can receive the satellite-signal of more than 4, just can carry out 3D location easily, but in some particular surroundings, as built-up down town, the forest highway of tree cover, underpass highway of overpass etc., because satellite-signal is very faint, traditional gps signal treatment technology can not process these feeble signals effectively in real time, cause location difficulty.

For GPS, the catching of satellite-signal, follow the tracks of, basis that demodulation is location navigation, one of its gordian technique is exactly the design of carrier tracking loop.Carrier wave ring tracking conventional at present has following four kinds of modes: (1) phaselocked loop track algorithm; (2) FLL track algorithm; (3) Kalman(Kalman) carrier wave ring track algorithm; (4) FLL assists phaselocked loop track algorithm.

Phaselocked loop track algorithm adopts narrower noise bandwidth, can closely tracking signal, but it is poor to the tolerance of dynamic stress.When noise is stronger or required loop bandwidth is larger, just likely there is difficulty to semaphore lock in phaselocked loop, causes signal losing lock.FLL track algorithm adopts wider noise bandwidth, and dynamic property is good, can follow the tracks of the signal that signal to noise ratio (S/N ratio) is lower, but insensitive to data bit saltus step, and loop noise is higher, and the bit error rate occurred in data demodulation process is also higher.Kalman filter can carry out instant prediction to the variation tendency of high dynamic signal.Therefore someone proposes Kalman carrier wave ring track algorithm and FLL assists phaselocked loop track algorithm.Kalman carrier wave ring track algorithm is replaced the loop filter Kalman filter in phaselocked loop, improves the dynamic stress of signal trace.But the observational variable of Kalman is only the identified result of the phase detector of phaselocked loop, just adjust each quantity of state according to identified result, still have certain limitation, cause low signal-to-noise ratio and dynamic stress larger time, still can not tracking lock signal well.FLL assists phaselocked loop track algorithm to make carrier wave ring can accurately follow the tracks of when dynamic is lower as phaselocked loop and measure carrier signal, and when dynamic is higher can as FLL firmly locking signal, improve the dynamic stress of signal trace, but due to the limitation of loop filter, make when signal to noise ratio (S/N ratio) is lower and dynamic property is higher, tracking sensitivity is poor, still can not tracking signal well.

Summary of the invention

The object of the present invention is to provide a kind of mode of operation according to carrier-to-noise ratio dynamic conditioning carrier wave ring and the gps satellite signal carrier wave ring tracking adopting Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL under low carrier-to-noise ratio and device, be intended to solve how according to the mode of operation of carrier-to-noise ratio dynamic conditioning carrier wave ring, and low signal-to-noise ratio and dynamic stress larger time, can not tracking lock signal well, the sensitivity of tracking and the poor problem of dynamic.

The invention provides a kind of gps satellite signal carrier wave ring tracking, comprising:

Obtain the carrier-to-noise ratio of satellite-signal;

When the carrier-to-noise ratio of described satellite-signal is greater than or equal to first threshold, carrier wave ring adopts FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, and described carrier wave ring comprises frequency discriminator, phase detector, loop filter, voltage controlled oscillator;

When the carrier-to-noise ratio of described satellite-signal is less than described first threshold, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, and described carrier wave ring comprises frequency discriminator, phase detector, Kalman filter, voltage controlled oscillator.

Further, described method also comprises:

In the process adopting Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, if the carrier-to-noise ratio of satellite-signal is strengthened to Second Threshold, then carrier wave ring switches to FLL and assists phase-lock-loop algorithm to follow the tracks of signal.

The invention provides also a kind of gps satellite signal carrier wave ring tracking means, comprising:

Acquisition module, FLL assists phase-locked loop module, and Kalman filtering assists phase-locked loop module in conjunction with FLL;

Described acquisition module, for obtaining the carrier-to-noise ratio of satellite-signal;

Described FLL assists phaselocked loop algoritic module, for when the carrier-to-noise ratio of described satellite-signal is greater than or equal to first threshold, carrier wave ring adopts FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, and described carrier wave ring comprises frequency discriminator, phase detector, loop filter, voltage controlled oscillator;

Described Kalman filtering assists phase-locked loop module in conjunction with FLL, for when the carrier-to-noise ratio of described satellite-signal is less than described first threshold, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, and described carrier wave ring comprises frequency discriminator, phase detector, Kalman filter, voltage controlled oscillator.

Further, described device also comprises:

Handover module, for in the process adopting Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, if the carrier-to-noise ratio of satellite-signal is strengthened to Second Threshold, then carrier wave ring switches to FLL and assists phase-lock-loop algorithm to follow the tracks of signal.

In the present invention, by obtaining the carrier-to-noise ratio of signal, when carrier-to-noise ratio is higher, carrier wave ring adopts FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, when carrier-to-noise ratio is lower, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, and in the process adopting Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, if the carrier-to-noise ratio of satellite-signal is strengthened to Second Threshold, then carrier wave ring switches to FLL and assists phase-lock-loop algorithm to follow the tracks of signal, make carrier wave ring can according to the mode of operation of the carrier-to-noise ratio dynamic conditioning carrier wave ring of satellite-signal like this, due to Kalman filtering calculation of complex, when carrier-to-noise ratio is strengthened to Second Threshold, switch to FLL again and assist phase-lock-loop algorithm, also hardware resource can be saved while raising tracking performance.Further when low carrier-to-noise ratio, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, combine Kalman filtering can to the variation tendency of high dynamic signal carry out instant prediction and FLL assist phaselocked loop track algorithm when dynamic is higher can as FLL the advantage of firmly locking signal, improve sensitivity and the dynamic of tracking, can tracking signal is more weak well satellite-signal when dynamic is larger.

Accompanying drawing explanation

Fig. 1 is the realization flow figure of the gps satellite signal carrier wave ring tracking that the embodiment of the present invention one provides;

Fig. 2 is the realization flow figure that the carrier wave ring that provides of the embodiment of the present invention two adopts Kalman filtering algorithm and assists phase-lock-loop algorithm to follow the tracks of satellite-signal in conjunction with FLL;

Fig. 3 is the structured flowchart of the gps satellite signal carrier wave ring tracking means that the embodiment of the present invention three provides.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

Fig. 1 shows the realization flow of a kind of gps satellite signal carrier wave ring tracking that the embodiment of the present invention one provides, and details are as follows:

The carrier-to-noise ratio of step 101, acquisition satellite-signal.

Calculate the carrier-to-noise ratio of satellite-signal, and obtain the carrier-to-noise ratio after calculating.Carrier-to-noise ratio refers to the average power of modulated signal, namely the ratio of carrier power and the average power of additive noise.

Step 102, judge whether carrier-to-noise ratio is more than or equal to first threshold, if so, then perform step 103, if not, then perform step 104.

Described first threshold is default value, can rule of thumb preset, and such as can preset described first threshold is 33dB, the carrier-to-noise ratio of acquisition is compared with this threshold value, qualitatively judges the carrier-to-noise ratio height of satellite-signal.

Step 103, carrier wave ring adopt FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, and described carrier wave ring comprises frequency discriminator, phase detector, loop filter, voltage controlled oscillator;

For automatic navigator, after trapping module captures satellite-signal, registration, enters the frequency pulling stage, enters locked stage after frequency pulling completes, and finds out the starting point of navigation bit in locked stage.Synchronous phase is entered after finding the starting point of navigation bit.At synchronous phase, when the carrier-to-noise ratio of described satellite-signal is greater than or equal to first threshold, carrier wave ring adopts FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, and described carrier wave ring comprises frequency discriminator, phase detector, loop filter, voltage controlled oscillator.Such as, when the carrier-to-noise ratio of satellite-signal is greater than or equal to first threshold 33dB, illustrate that carrier-to-noise ratio is higher, when carrier-to-noise ratio is higher, carrier wave ring adopts FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, and tracking can reach reasonable effect.

Step 104, carrier wave ring adopt Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, and described carrier wave ring comprises frequency discriminator, phase detector, Kalman filter, voltage controlled oscillator.

At synchronous phase, when the carrier-to-noise ratio of described satellite-signal is less than described first threshold, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, and described carrier wave ring comprises frequency discriminator, phase detector, Kalman filter, voltage controlled oscillator.Such as, when carrier-to-noise ratio is lower than first threshold 33dB, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL.Due to when carrier-to-noise ratio is lower, carrier wave ring assists the restriction of phase-lock-loop algorithm loop filter by FLL, tracking performance is not fine, adopt Kalman filtering algorithm to assist phase-lock-loop algorithm in conjunction with FLL, FLL assisted phase-lock-loop algorithm loop filter Kalman filter to substitute.Kalman filtering can carry out instant prediction to the variation tendency of high dynamic signal, therefore can improve tracking performance under low signal-to-noise ratio.

Further, in described step 103, FLL assists phaselocked loop track algorithm to adopt single order FLL to assist the mode of second-order PLL.Described FLL adopts four-quadrant arctan function frequency discriminator, and obtain the rate of change of frequency, computing formula is: wherein

P _cross=Q _p(n) * I _p(n-1)-I _p(n) * Q _p(n-1), P _dot=I _p(n) * I _p(n-1)+Q _p(n) * Q _p(n-1), I _p, Q _pthe gps signal being respectively reception reappears signal in orthogonal component (Q road) coherent integration results with the gps signal received with local with the local signal in-phase component (I road) that reappears, and n is the result of current time, and n-1 was the result in a upper moment.

Because four-quadrant arctan function frequency discriminator exists the impact of bit saltus step, the result of this frequency discriminator to participate in the tracking of carrier wave ring directly, and thus carry out suitable correction to the result of frequency discriminator, prevent the impact of data bit saltus step, alter mode is: output phase value be θ, when abs (θ) < pi/2, θ=θ; When abs (θ) > pi/2, θ=θ-sign (θ) * π.

Described phaselocked loop adopts two quadrant arctan function phase detector, obtains phase value.Computing formula is: u _d=arctan (Q _p(n)/I _p(n)), wherein I _p, Q _p, n definition identical with the definition of above-mentioned frequency discriminator.This is a kind of Costas(Cohan tower) identified result of phaselocked loop, this identified result can work in numeric data code modulated carrier signal situation, insensitive to 180 ° of carrier wave phase transformations caused by data bit saltus step.When actual phase difference dystopy is within the scope of-90 ° to+90 °, the work of this phase detector keeps linear, and its identified result exported and signal amplitude have nothing to do.Two quadrant arctan function phase detector is the most a kind of in various Costas phaselocked loop phase detector.

In order to reduce calculated amount, above-mentioned frequency discriminator and phase detector all adopt the mode of tabling look-up to obtain.Then utilize single order FLL to assist the loop filter of second-order PLL, carry out filtering process to signal, adjustment is followed the tracks of and is carried wave frequency, follows the tracks of input satellite-signal.

Further, after performing step 104, also comprise:

Judge whether the carrier-to-noise ratio of signal is strengthened to Second Threshold, if it is carrier wave ring switches to FLL and assists phase-lock-loop algorithm to follow the tracks of signal.Such as, carrier wave ring is under Kalman filtering algorithm assists phaselocked loop algorithm pattern in conjunction with FLL, when the carrier-to-noise ratio enhancing of signal arrives certain carrier-to-noise ratio, such as 35dB, then move back Kalman filtering algorithm and assist phase-lock-loop algorithm algorithm pattern in conjunction with FLL, enter FLL and assist phaselocked loop algorithm keeps track pattern.Due to Kalman filtering calculation of complex, when carrier-to-noise ratio is strengthened to Second Threshold, then switches to FLL and assist phase-lock-loop algorithm, while raising tracking performance, also can save hardware resource.

In order to carrier wave ring in more detailed description embodiment one step 104 adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal in conjunction with FLL, in the embodiment of the present invention two by reference to the accompanying drawings 2, Kalman filtering algorithm is adopted to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal in conjunction with FLL to described carrier wave ring, be further described, details are as follows:

Described carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal in conjunction with FLL, comprising:

Step 201, according to model and the reproduction signal model of Received signal strength, choose " phase difference between Received signal strength and reproduction signal ", " Doppler shift of Received signal strength " and " Received signal strength Doppler shift rate of change " is as the state vector of Kalman filter model, the state equation of Kalman filter is set up according to the relation of state vector, described state equation is: X (k)=Φ X (k-1)+B (k-1)+W (k-1), wherein X (k) represents k moment system state vector, X (k-1) represents the system state vector in k-1 moment, B (k-1) represents k-1 moment state control vector, W (k-1) represents k-1 etching process noise vector, Φ represents state-transition matrix.In general gps system, state-transition matrix $\mathrm{\&Phi;}=\left[\begin{array}{ccc}1& 2\mathrm{\&pi;T}& 2\mathrm{\&pi;}\frac{T^2}{2}\\ 0& 1& T\\ 0& 0& 1\end{array}\right],$ Wherein T is integral time, the state control vector in k-1 moment $B(k-1)=-\left[\begin{array}{c}2\mathrm{\&pi;T}\\ 0\\ 0\end{array}\right]{\hat{f}}_d,$ for the Doppler-frequency estimation value in a upper moment, can obtain equations of state is thus:

$X\left(k\right)=\left[\begin{array}{c}{\mathrm{\&theta;}}_e\\ f_d\left(k\right)\\ {\mathrm{\&alpha;}}_d\left(k\right)\end{array}\right]=\left[\begin{array}{ccc}1& 2\mathrm{\&pi;T}& 2\mathrm{\&pi;}\frac{T^2}{2}\\ 0& 1& T\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{\mathrm{\&theta;}}_e(k-1)\\ f_d(k-1)\\ {\mathrm{\&alpha;}}_d(k-1)\end{array}\right]-\left[\begin{array}{c}2\mathrm{\&pi;T}\\ 0\\ 0\end{array}\right]{\hat{f}}_d+\left[\begin{array}{c}{w}_{{\mathrm{\&theta;}}_e}\\ w_{f_d}\\ w_{{\mathrm{\&alpha;}}_d}\end{array}\right],$ θ _e(k), f _d(k), α _dk () represents phase difference value, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength between k reception signal and reproduction signal respectively, θ _e(k-1), f _d(k-1), α _d(k-1) phase difference value, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength between k-1 reception signal and reproduction signal is represented respectively.θ _e, f _d, α _dinitial value respectively by the n preserved recently (such as 32) " phase difference between Received signal strength and reproduction signal ", " Doppler shift of Received signal strength " and " Received signal strength Doppler shift rate of change " averaging obtains.K-1 etching process noise vector $W(k-1)=\left[\begin{array}{c}{w}_{{\mathrm{\&theta;}}_e}\\ w_{f_d}\\ w_{{\mathrm{\&alpha;}}_d}\end{array}\right],$ represent the noise element corresponding with the Doppler shift rate of change of the Doppler shift of the phase difference value between k-1 reception signal and reproduction signal, Received signal strength, Received signal strength respectively.

Step 202, choose the frequency discrimination result of frequency discriminator and the identified result of phase detector two observational variables as Kalman filtering observation vector, observation equation is set up by the relation between observation vector and state vector, described observation equation is: Z (k)=HX (k)+C (k)+V (k), wherein Z (k) represents the observation vector in k moment, H is observing matrix, C (k) represents observer state control vector, and V (k) represents k moment observation noise vector.In general gps system, observing matrix $H=\left[\begin{array}{ccc}1& 2\mathrm{\&pi;}\frac{T}{2}& 2\mathrm{\&pi;}\frac{T^2}{6}\\ 0& 0& 1\end{array}\right],$ Observer state control vector $C\left(k\right)=\left[\begin{array}{c}-2\mathrm{\&pi;}\frac{T}{2}{\hat{f}}_d\\ 0\end{array}\right],$ Can obtain observation equation is thus:

$Z\left(k\right)=\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&theta;}}}_e\\ {\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_d\end{array}\right]=\left[\begin{array}{ccc}1& 2\mathrm{\&pi;}\frac{T}{2}& 2\mathrm{\&pi;}\frac{T^2}{6}\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{\mathrm{\&theta;}}_e\left(k\right)\\ f_d\left(k\right)\\ {\mathrm{\&alpha;}}_d\left(k\right)\end{array}\right]+\left[\begin{array}{c}-2\mathrm{\&pi;}\frac{T}{2}{\hat{f}}_d\\ 0\end{array}\right]+\left[\begin{array}{c}{v}_{{\stackrel{\&OverBar;}{\mathrm{\&theta;}}}_e}\\ v_{{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_d}\end{array}\right],$ Wherein, Z (k) represents the observation vector in k moment, represent the observation noise in frequency discrimination result and identified result respectively.

Kalman filter algorithm recurrence equation is as follows:

(1) one step status predication equation: X (k, k-1)=Φ X (k-1)+B (k-1)

(2) one step error covariance predictive equation: P (k, k-1)=Φ P (k-1) Φ ^t+ Q _n(k-1);

(3) filter gain matrix equation: K (k)=P (k, k-1) H ^t[HP (k, k-1) H ^t+ R (k-1)] ^-1;

(4) state optimization estimate equation: X (k)=X (k, k-1)+K (k) [Z (k)-HX (k, k-1)-C (k)];

(5) optimal estimation error covariance equation: P (k)=(I-K (k) H) P (k, k-1);

Wherein, P (k-1) represents the error co-variance matrix in k-1 moment, and P (k) represents the error co-variance matrix in k moment, and the error co-variance matrix in k moment is predicted in P (k, k-1) expression from the k-1 moment, Q _n(k-1) covariance matrix of k-1 moment system noise W (k-1) is represented, K (k) represents filter gain matrix, and R (k-1) represents the covariance matrix of k-1 moment observation noise, and I represents that diagonal entry is 1, all the other elements are the matrix of 0, Φ ^t, H ^trepresent the transposed matrix of Φ, H respectively.

The initial value of described P (k-1) asks covariance to obtain by the n preserved recently (such as 32) " phase difference between Received signal strength and reproduction signal ", " Doppler shift of Received signal strength " and " Received signal strength Doppler shift rate of change ".

The covariance matrix Q of described k moment system noise W (k) _n(k) be:

$Q_n\left(k\right)=q_{\mathrm{los}}\left[\begin{array}{ccc}\frac{T^5}{20}& \frac{T^4}{8}& \frac{T^3}{6}\\ \frac{T^4}{8}& \frac{T^3}{3}& \frac{T^2}{2}\\ \frac{T^3}{6}& \frac{T^2}{2}& T\end{array}\right]+S_g{w}_{L1}^2\left[\begin{array}{ccc}\frac{T^3}{3}& \frac{T^2}{2}& 0\\ \frac{T^2}{2}& T& 0\\ 0& 0& 0\end{array}\right]+S_f{w}_{L1}^2\left[\begin{array}{ccc}T& 0& 0\\ 0& 0& 0\\ 0& 0& 0\end{array}\right];$ Wherein, q _losrepresent acceleration random walk intensity, q _losbe an empirical value, T represents coherent integration time, S _gfor frequency accidental swinging strength, S _frepresent the random swinging strength of phase place.When the oscillator of system is temperature compensating crystal oscillator (TCXO), S _f=5*10 ^-21, S _g=5.9*10 ^-20; When the oscillator of system is constant-temperature crystal oscillator (OXO), S _f=5*10 ^-23, S _g=5.9*10 ^-22.W _l1for L1 carries wave frequency:

w _L1=154*10.23MHz。

R (k-1) is observation noise covariance matrix, often does n (such as 32 times) kalman filtering and upgrades once.Covariance is asked to obtain by the mean value of the frequency discrimination result of n time and identified result mean value.

Step 203, the state equation according to described, observation equation, a step status predication equation, a step error covariance predictive equation, filter gain matrix, state optimization estimate equation, optimal estimation error covariance equation calculate current time state optimization estimated value, and current optimal estimation value are sent to described voltage controlled oscillator.

The state optimization estimated value that step 204, described voltage controlled oscillator export according to Kalman filter, the reproduction frequency of carrier signal that adjustment exports, follows the tracks of the satellite-signal received.

Fig. 3 shows the structured flowchart of a kind of gps satellite signal carrier wave ring tracking means that the embodiment of the present invention three provides, and described device comprises acquisition module 31, and FLL assists phase-locked loop module 32, and Kalman filtering assists phase-locked loop module 33 in conjunction with FLL; Described acquisition module 31, for obtaining the carrier-to-noise ratio of satellite-signal number; Described FLL assists phase-locked loop module 32, for when the carrier-to-noise ratio of described satellite-signal is greater than or equal to first threshold, carrier wave ring adopts FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, and described carrier wave ring comprises frequency discriminator, phase detector, loop filter, voltage controlled oscillator; Described Kalman filtering assists phase-locked loop module 33 in conjunction with FLL, for when the carrier-to-noise ratio of described satellite-signal is less than described first threshold, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, and described carrier wave ring comprises frequency discriminator, phase detector, Kalman filter, voltage controlled oscillator.

Further, described device also comprises handover module 34, for in the process adopting Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, if the carrier-to-noise ratio of satellite-signal is strengthened to Second Threshold, then carrier wave ring switches to FLL and assists phase-lock-loop algorithm to follow the tracks of signal.

Further, described carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal in conjunction with FLL, comprising:

According to model and the reproduction carrier signal model of Received signal strength, choose phase difference value, the Doppler shift of Received signal strength and Received signal strength Doppler shift rate of change between Received signal strength and reproduction signal as the state vector of Kalman filter model, obtain the state equation of Kalman filtering;

Using the frequency discrimination result of frequency discriminator and the identified result of phase detector as two observational variables of Kalman filtering observation vector, according to described observation vector and state vector, obtain the observation equation of Kalman filtering;

According to a step status predication equation, a step error covariance predictive equation, filter gain matrix, state optimization estimate equation, the optimal estimation error covariance equation of described state equation and observation equation and Kalman filtering, calculate the state optimization estimated value that Kalman filter described in current time exports, and described state optimization estimated value is sent to described voltage controlled oscillator;

The state optimization estimated value that voltage controlled oscillator exports according to Kalman filter, the reproduction frequency of carrier signal that adjustment exports, follows the tracks of the satellite-signal received.

In described state equation, the system state vector in k-1 moment is: $X(k-1)=\left[\begin{array}{c}{\mathrm{\&theta;}}_e(k-1)\\ f_d(k-1)\\ {\mathrm{\&alpha;}}_d(k-1)\end{array}\right],$ θ _e(k-1), f _d(k-1), α _d(k-1) phase difference value, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength between k-1 reception signal and reproduction signal is represented respectively, θ _e, f _d, α _dinitial value is respectively n Received signal strength preserving recently and reappears the mean value of phase difference between signal, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength.

Described observation equation is: $Z\left(k\right)=\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&theta;}}}_e\\ {\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_d\end{array}\right]=\left[\begin{array}{ccc}1& 2\mathrm{\&pi;}\frac{T}{2}& 2\mathrm{\&pi;}\frac{T^2}{6}\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{\mathrm{\&theta;}}_e\left(k\right)\\ f_d\left(k\right)\\ {\mathrm{\&alpha;}}_d\left(k\right)\end{array}\right]+\left[\begin{array}{c}-2\mathrm{\&pi;}\frac{T}{2}{\hat{f}}_d\\ 0\end{array}\right]+\left[\begin{array}{c}{v}_{{\stackrel{\&OverBar;}{\mathrm{\&theta;}}}_e}\\ v_{\stackrel{\&OverBar;}{{\mathrm{\&alpha;}}_d}}\end{array}\right],$ Wherein Z (k) represents the observation vector in k moment, represent identified result, represent frequency discrimination result, θ _e(k), f _d(k), α _dk () represents phase difference value, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength between k reception signal and reproduction signal respectively, for the Doppler-frequency estimation value in a upper moment, represent the observation noise in frequency discrimination result and identified result respectively, T represents coherent integration time.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. a gps satellite signal carrier wave ring tracking, is characterized in that, comprising:

Obtain the carrier-to-noise ratio of satellite-signal;

When the carrier-to-noise ratio of described satellite-signal is greater than or equal to first threshold, carrier wave ring adopts FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, and described carrier wave ring comprises frequency discriminator, phase detector, loop filter, voltage controlled oscillator;

When the carrier-to-noise ratio of described satellite-signal is less than described first threshold, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, and described carrier wave ring comprises frequency discriminator, phase detector, Kalman filter, voltage controlled oscillator.

2. the method for claim 1, is characterized in that, described method also comprises:

In the process adopting Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, if the carrier-to-noise ratio of satellite-signal is strengthened to Second Threshold, then carrier wave ring switches to FLL and assists phase-lock-loop algorithm to follow the tracks of signal.

3. method as claimed in claim 1 or 2, is characterized in that, described carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal in conjunction with FLL, comprising:

According to model and the reproduction carrier signal model of Received signal strength, choose phase difference value, the Doppler shift of Received signal strength and Received signal strength Doppler shift rate of change between Received signal strength and reproduction signal as the state vector of Kalman filter model, obtain the state equation of Kalman filtering according to described state vector;

Using the frequency discrimination result of frequency discriminator and the identified result of phase detector as two observational variables of Kalman filtering observation vector, obtain the observation equation of Kalman filtering according to described observation vector and state vector;

Calculate the state optimization estimated value that Kalman filter described in current time exports according to a step status predication equation of described state equation and observation equation and Kalman filtering, a step error covariance predictive equation, filter gain matrix, state optimization estimate equation, optimal estimation error covariance equation, and described state optimization estimated value is sent to described voltage controlled oscillator;

The state optimization estimated value that described voltage controlled oscillator exports according to Kalman filter, the reproduction frequency of carrier signal that adjustment exports, follows the tracks of the satellite-signal received.

4. method as claimed in claim 3, it is characterized in that, in described state equation, the system state vector in k-1 moment is X (k-1), described in $X(k-1)=\left[\begin{array}{c}{\mathrm{\&theta;}}_e(k-1)\\ f_d(k-1)\\ {\mathrm{\&alpha;}}_d(k-1)\end{array}\right],$ θ _e(k-1), f _d(k-1), α _d(k-1) phase difference value, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength between k-1 reception signal and reproduction signal is represented respectively, θ _e, f _d, α _dinitial value is respectively n Received signal strength preserving recently and reappears the mean value of phase difference between signal, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength.

5. the method as described in claim 3 or 4, is characterized in that, described observation equation is: $Z\left(k\right)=\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&theta;}}}_e\\ {\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_d\end{array}\right]=\left[\begin{array}{ccc}1& 2\mathrm{\&pi;}\frac{T}{2}& 2\mathrm{\&pi;}\frac{T^2}{6}\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{\mathrm{\&theta;}}_e\left(k\right)\\ f_d\left(k\right)\\ {\mathrm{\&alpha;}}_d\left(k\right)\end{array}\right]+\left[\begin{array}{c}-2\mathrm{\&pi;}\frac{T}{2}{\hat{f}}_d\\ 0\end{array}\right]+\left[\begin{array}{c}{v}_{{\stackrel{\&OverBar;}{\mathrm{\&theta;}}}_e}\\ v_{\stackrel{\&OverBar;}{{\mathrm{\&alpha;}}_d}}\end{array}\right],$ Wherein Z (k) represents the observation vector in k moment, represent identified result, represent frequency discrimination result, θ _e(k), f _d(k), α _dk () represents phase difference value, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength between k reception signal and reproduction signal respectively, for the Doppler-frequency estimation value in a upper moment, represent the observation noise in frequency discrimination result and identified result respectively, T represents coherent integration time.

6. a gps satellite signal carrier wave ring tracking means, is characterized in that, comprising:

Acquisition module, FLL assists phase-locked loop module, and Kalman filtering assists phase-locked loop module in conjunction with FLL;

Described acquisition module, for obtaining the carrier-to-noise ratio of signal;

Described FLL assists phase-locked loop module, for when the carrier-to-noise ratio of described satellite-signal is greater than or equal to first threshold, carrier wave ring adopts FLL to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal, and described carrier wave ring comprises frequency discriminator, phase detector, loop filter, voltage controlled oscillator;

Described Kalman filtering assists phase-locked loop module in conjunction with FLL, for when the carrier-to-noise ratio of described satellite-signal is less than described first threshold, carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, and described carrier wave ring comprises frequency discriminator, phase detector, Kalman filter, voltage controlled oscillator.

7. device as claimed in claim 6, it is characterized in that, described device also comprises:

Handover module, for in the process adopting Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of signal in conjunction with FLL, if the carrier-to-noise ratio of satellite-signal is strengthened to Second Threshold, then carrier wave ring switches to FLL and assists phase-lock-loop algorithm to follow the tracks of signal.

8. device as claimed in claims 6 or 7, is characterized in that, described carrier wave ring adopts Kalman filtering algorithm to assist phase-lock-loop algorithm to follow the tracks of described satellite-signal in conjunction with FLL, comprising:

According to model and the reproduction carrier signal model of Received signal strength, choose phase difference value, the Doppler shift of Received signal strength and Received signal strength Doppler shift rate of change between Received signal strength and reproduction signal as the state vector of Kalman filter model, obtain the state equation of Kalman filtering according to described state vector;

Using the frequency discrimination result of frequency discriminator and the identified result of phase detector two observational variables as Kalman filtering observation vector, obtain the observation equation of Kalman filtering according to described observation vector, state vector;

Calculate the state optimization estimated value that Kalman filter described in current time exports according to a step status predication equation of described state equation and observation equation and Kalman filtering, a step error covariance predictive equation, filter gain matrix, state optimization estimate equation, optimal estimation error covariance equation, and described state optimization estimated value is sent to described voltage controlled oscillator;

The state optimization estimated value that described voltage controlled oscillator exports according to Kalman filter, the reproduction frequency of carrier signal that adjustment exports, follows the tracks of the satellite-signal received.

9. device as claimed in claim 8, it is characterized in that in described state equation, the system state vector in k-1 moment is X (k-1), described in $X(k-1)=\left[\begin{array}{c}{\mathrm{\&theta;}}_e(k-1)\\ f_d(k-1)\\ {\mathrm{\&alpha;}}_d(k-1)\end{array}\right],$ θ _e(k-1), f _d(k-1), α _d(k-1) phase difference value, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength between k-1 reception signal and reproduction signal is represented respectively, θ _e, f _d, α _dinitial value is respectively n Received signal strength preserving recently and reappears the mean value of phase difference between signal, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength.

10. device as claimed in claim 8, it is characterized in that, described observation equation is: $Z\left(k\right)=\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&theta;}}}_e\\ {\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}_d\end{array}\right]=\left[\begin{array}{ccc}1& 2\mathrm{\&pi;}\frac{T}{2}& 2\mathrm{\&pi;}\frac{T^2}{6}\\ 0& 0& 1\end{array}\right]\left[\begin{array}{c}{\mathrm{\&theta;}}_e\left(k\right)\\ f_d\left(k\right)\\ {\mathrm{\&alpha;}}_d\left(k\right)\end{array}\right]+\left[\begin{array}{c}-2\mathrm{\&pi;}\frac{T}{2}{\hat{f}}_d\\ 0\end{array}\right]+\left[\begin{array}{c}{v}_{{\stackrel{\&OverBar;}{\mathrm{\&theta;}}}_e}\\ v_{\stackrel{\&OverBar;}{{\mathrm{\&alpha;}}_d}}\end{array}\right],$ Wherein Z (k) represents the observation vector in k moment, represent identified result, represent frequency discrimination result, θ _e(k), f _d(k), α _dk () represents phase difference value, the Doppler shift of Received signal strength, the Doppler shift rate of change of Received signal strength between k reception signal and reproduction signal respectively, for the Doppler-frequency estimation value in a upper moment, represent the observation noise in frequency discrimination result and identified result respectively, T represents coherent integration time.