CN104251997A - Satellite signal anti-interference sparse processing method - Google Patents

Abstract

The invention provides a satellite signal anti-interference sparse processing method, and relates to a base band signal processing method in the technical field of satellite navigation. The method comprises the following steps of extracting two subsignals from the satellite navigation signal in a parity bit way, and performing fast Fourier conversion; utilizing the threshold empirical value to zero one of the two frequency domain subsignals of which the mode value is smaller than the threshold value; performing the sparse processing on the obtained frequency domain signal, and performing the fast Fourier conversion to obtain two new time domain signals; combining into a new satellite navigation medium-frequency signal in a parity sequence; capturing the new medium-frequency signal to complete the capturing work. The method has the advantages that the high gauss noise in the satellite signal can be effectively removed, the capturing accuracy and sensitivity are obviously improved, the method is simple, and the operation speed is high; the method is suitable for four satellite systems, namely COMPASS, GPS (global positioning system), GLONASS and GALILEO.

Description

The anti-interference sparse disposal route of a kind of satellite-signal

Technical field

The present invention relates to satellite navigation signals process field, in particular to the sparse anti-interference method of a kind of compatible with COM PASS (Chinese Beidou satellite navigation system: BeiDou Navigation Satellite System is called for short the Big Dipper or BD or BeiDou), GPS (US Global global position system: Global Position System), GLONASS (Russia's GPS GLONASS) and GALILEO (European Galileo satellite positioning system) four large satellite system.

Background technology

Satellite-signal is owing to limiting by factors such as costs, its emissive power is often less, before arrival ground receiver, it also can be subject to the interference of various factors (as noise) and decay, the satellite-signal that general satellite reception function receives is submerged in noise often, this can to signal catch and tracking causes certain difficulty, even cannot realize the effective reception to signal.Therefore, satellite-signal is carried out carrying out elimination to interference such as noises before catching and following the tracks of process and seem necessary.The satellite-signal be interfered can represent with formula below:

y＝s+n

Wherein, y represents the signal of noise that adulterates received, and s is raw satellite signal, and n is the interference such as noise.If the noise item n in above formula is known, so just can calculate required satellite-signal s, but this situation can not occur, because the interference such as noise is stochastic distribution, the deviation that it can make original signal and observation signal keep certain.In Sparse Signal Representation theory, sparse dictionary function x can be adopted to represent for useful signal (being different from noise):

s＝Dx

Wherein, s is original signal, and D is feature bases, and x is random combine coefficient and sparse coefficient.

Above formula can be understood as signal s in specific dictionary D, can represent with sparse coefficient x.Utilize rarefaction representation to solve the interference problem of signal, can represent with following formula:

$\underset{x}{\min }{\left|\right|X\left|\right|}_0,s.t{\left|\right|\mathrm{Dx}-y\left|\right|}_2^2\≤\mathrm{\ϵ}$

In formula, threshold epsilon and noise are closely connected, and the denoising of signal is just converted into the process solving nonzero value x.

It is unpractical for being removed completely by noise, if reproducing signal can be made as far as possible close to original signal, so when occurring that minimum mean error is approached, namely achieves comparatively stable denoising effect.

In the prior art, the anti-interference problem solving satellite-signal is generally realized by the method for enhancing signal transacting gain, such as coherent integration method, non-coherent integration method and differential coherence integration method etc., but these disposal routes are just according to the different objects that reach signal strengthen of signal from noise processing gain in integral process, and its essence does not have the interference noise in erasure signal.

Summary of the invention

The object of the invention is to the shortcoming and defect overcoming existing satellite-signal disposal route, propose one and can effectively remove strong Gaussian noise, improve the anti-interference sparse disposal route of satellite-signal of acquisition sensitivity, the present invention is directed to the satellite navigation signals be under strong interference environment and carry out anti-interference sparse disposal route, computing is simple, accuracy is high, for the interference problem better solving satellite-signal provides important theory value and realistic meaning.

The present invention is achieved through the following technical solutions: the anti-interference sparse disposal route of satellite-signal of the present invention, comprises the steps:

1) satellite-signal receives through antenna and obtains intermediate-freuqncy signal r (t) after mixing sampling, and r (t) is taken into two subsignal r by odd even _e(t) and r _o(t), wherein r _et even number point signal that () is r (t), r _ot odd point signal that () is r (t);

2) by above-mentioned two subsignal r _e(t), r _ot () is carried out Fast Fourier Transform (FFT) respectively and is obtained R _eand R (K) _o(K); Then thresholding empirical value φ is set ₁, by R _eand R (K) _o(K) in, modulus value is less than empirical value φ ₁subsignal be set to 0 and obtain new signal R _e1and R (K) _o1(K);

3) to the signal R newly obtained _e1and R (K) _o1(K) carry out sparse process and obtain R _e2and R (K) _o2(K);

4) to the above-mentioned frequency-region signal R through sparse process _e2and R (K) _o2(K) carry out inverse fast Fourier transform and obtain new time-domain signal r _e2(t) and r _o2t (), then merges pending signal r` (t) obtaining removing interference in order by odd, even signal;

5) process is caught to above-mentioned signal r` (t) through sparse anti-interference process, thus complete satellite navigation signals catch work.

Above-mentioned steps 2) in, by two subsignal r _e(t), r _ot () is carried out Fast Fourier Transform (FFT) respectively and is obtained R _eand R (K) _o(K) method is as follows:

Two subsignals extracted are done respectively the computing of windowing FFT in short-term of 2046, so that signal is converted to frequency-domain analysis by time-domain analysis, definition rectangular window function m (t)=1, then for the frequency-region signal R of this section _eand R (K) _o(K) drawn by following formula:

$R_e\left(K\right)=\underset{t=1}{\overset{2046}{\mathrm{\Σ}}}{r}_e\left(t\right)W_{2046}^{\mathrm{tK}},(K=\mathrm{1,2},...,2046)$

$R_o\left(K\right)=\underset{t=1}{\overset{2046}{\mathrm{\Σ}}}{r}_o\left(t\right)W_{2046}^{\mathrm{tK}},(K=\mathrm{1,2},...,2046)$

Wherein: refer to the Fast Fourier Transform (FFT) factor, r _et () refers to the even number point signal of extraction, r _ot () refers to the odd point signal of extraction.

Above-mentioned steps 3) in, to signal R _e1and R (K) _o1(K) operation carrying out sparse process is as follows: to R _e1and R (K) _o1(K) delivery obtains | R _e1(K) | with | R _o1(K) |; Empirical value φ is set ₂, when | R _e1(K) | be less than empirical value φ ₂time, make R _o1(K) equal zero; When | R _o1(K) | be less than empirical value φ ₂time, make R _e1(K) equal zero; Obtain new frequency-region signal R _e2and R (K) _o2(K), the sparse process of settling signal.

Above-mentioned steps 4) in, to the frequency-region signal R through sparse process _e2and R (K) _o2(K) carry out inverse fast Fourier transform and obtain new time-domain signal r _e2(t) and r _o2t the method for () is as follows:

After sparse process two frequency-region signal is carried out to the IFFT of the windowing in short-term computing of 2046, definition rectangular window function m (t)=1, then for the time-domain signal r of this section _e2(t) and r _o2t () is drawn by following formula:

$r_{e2}\left(t\right)=\underset{t=1}{\overset{2046}{\mathrm{\Σ}}}{R}_{e2}\left(K\right)W_{2046}^{\mathrm{Kt}},(t=\mathrm{1,2},...,2046)$

$r_{o2}\left(t\right)=\underset{K=1}{\overset{2046}{\mathrm{\Σ}}}{R}_{o2}\left(K\right)W_{2046}^{\mathrm{Kt}},(t=\mathrm{1,2},...,2046)$

Wherein: refer to the inverse fast Fourier transform factor, R _e2(K) the even number point frequency-region signal through sparse process is referred to, R _o2(K) refer to the odd point frequency-region signal through sparse process, signal is transformed into time domain by frequency domain, obtains new strange signal r _o2(t) and even signal r _e2(t).

Above-mentioned steps 5) in, process is caught to above-mentioned signal r` (t) through sparse anti-interference process, thus the method completing the work of catching of satellite navigation signals is as follows: carry out two-dimensional search to the signal through sparse anti-interference process in pseudo-code phase territory and carrier Doppler frequency territory, find out the pseudo-code phase value corresponding to correlation peak and carrier Doppler frequency value, thus determine the pseudo-code phase in input signal and carrier frequency.

The anti-interference sparse disposal route of satellite-signal of the present invention, compatible with COM PASS, GPS, GLONASS and GALILEO tetra-large satellite system.

Compared with prior art, tool has the following advantages and beneficial effect in the present invention:

The anti-interference sparse disposal route of satellite-signal of the present invention extracts by parity bit satellite intermediate frequency signal, then the method for sparse process is recycled after it being processed in frequency domain to strengthen signal quality, this is by the impact of noise in larger erasure signal, significantly improve acquisition accuracy and sensitivity, method is simple, fast operation, accuracy is high.The present invention is that one can effectively remove strong Gaussian noise, improves the anti-interference sparse disposal route of satellite-signal of acquisition sensitivity.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of the inventive method;

Fig. 2 is the sparse handling principle figure in the present invention;

Fig. 3 is odd point in the present invention and even number point spectrogram;

Fig. 4 is the signal discrete figure before arranging thresholding in the present invention;

Fig. 5 is the signal discrete figure after arranging thresholding in the present invention;

Fig. 6 is the graph of a relation of correlation peak and threshold value in the present invention;

Fig. 7 is the new signal schematic diagram after parity signal synthesis;

Fig. 8 be the inventive method catch result figure.

Embodiment

Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are not limited thereto.

Embodiment:

As shown in Figure 1, the present invention is based on sparse process and propose a kind of satellite-signal anti-interference method, comprise the steps:

1) satellite-signal is after antenna receives, and becomes intermediate-freuqncy signal r (t), r (t) is taken into two subsignal r after mixing sampling _e(t) and r _o(t), wherein r _et even number point signal that () is r (t), r _ot odd point signal that () is r (t).

2) by above-mentioned two subsignal r _e(t), r _ot () is carried out Fast Fourier Transform (FFT) respectively and is obtained R _eand R (K) _o(K) then, thresholding empirical value φ be set ₁, by R _eand R (K) _o(K) in, modulus value is less than empirical value φ ₁subsignal be set to 0, obtain new signal R _e1and R (K) _o1(K).

3) to the signal R newly obtained _e1and R (K) _o1(K) carry out sparse process and obtain R _e2and R (K) _o2(K).

4) to the above-mentioned frequency-region signal R through sparse process _e2and R (K) _o2(K) carry out inverse fast Fourier transform and obtain new time-domain signal r _e2(t) and r _o2t (), then merges pending signal r` (t) obtaining removing interference in order by odd, even signal.

5) process is caught to above-mentioned signal r` (t) through sparse anti-interference process, thus complete satellite navigation signals catch work.

In the present embodiment, step 2) process be:

Intermediate-freuqncy signal r (t) is taken into odd even two subsignal x ₁(t) and x ₂t (), then does the windowed FFT in short-term of 2046 to it, as shown in Figure 3, wherein " * " represents the spectrogram of even number point signal to result, and " o " represents the spectrogram of odd point signal.Signal scatter diagram before threshold value is set, as shown in Figure 4.Then by threshold value φ ₁be set to 19, removal unit sub-signal, delivery obtains result, as shown in Figure 5.

When threshold value is 0 ~ 200 cycle calculations, catch the relation of the highest correlation peak and the threshold value obtained as shown in Figure 6, known as threshold value mm=19, it is maximum for catching the correlation peak obtained.

Concrete described step 4) in new signal R _e1and R (K) _o1(K) sparse process operation is carried out as follows:

Empirical value φ is set ₂=0, when | R _e1(K) | be less than empirical value φ ₂time, make R _o1(K) equal zero; When | R _o1(K) | be less than empirical value φ ₂time, make R _e1(K) equal zero; Obtain new frequency-region signal R _e2and R (K) _o2(K), sparse process is completed.

Concrete described step 5) in obtain new time-domain signal after, by odd even order, even number point signal and odd point signal are arranged in new signal r` (t), as shown in Figure 7.

Concrete described step 6) utilize synthesis new signal to carry out catching effect as shown in Figure 8, as a comparison, the inventive method can effectively improve signal capture quality, improves acquisition performance, strengthens the antijamming capability of satellite-signal.

Above-described embodiment is the present invention's preferably embodiment; but embodiments of the present invention are not restricted to the described embodiments; change, the modification done under other any does not deviate from Spirit Essence of the present invention and principle, substitute, combine, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.

Claims (6)

1. the anti-interference sparse disposal route of satellite-signal, is characterized in that comprising the steps:

1) satellite-signal receives through antenna and obtains intermediate-freuqncy signal r (t) after mixing sampling, and r (t) is taken into two subsignal r by odd even _e(t) and r _o(t), wherein r _et even number point signal that () is r (t), r _ot odd point signal that () is r (t);

2) by above-mentioned two subsignal r _e(t), r _ot () is carried out Fast Fourier Transform (FFT) respectively and is obtained R _eand R (K) _o(K); Then thresholding empirical value φ is set ₁, by R _eand R (K) _o(K) in, modulus value is less than empirical value φ ₁subsignal be set to 0 and obtain new signal R _e1and R (K) _o1(K);

3) to the signal R newly obtained _e1and R (K) _o1(K) carry out sparse process and obtain R _e2and R (K) _o2(K);

4) to the above-mentioned frequency-region signal R through sparse process _e2and R (K) _o2(K) carry out inverse fast Fourier transform and obtain new time-domain signal r _e2(t) and r _o2t (), then merges pending signal r` (t) obtaining removing interference in order by odd, even signal;

5) process is caught to above-mentioned signal r` (t) through sparse anti-interference process, thus complete satellite navigation signals catch work.

2. the anti-interference sparse disposal route of satellite-signal according to claim 1, is characterized in that above-mentioned steps 2) in, by two subsignal r _e(t), r _ot () is carried out Fast Fourier Transform (FFT) respectively and is obtained R _eand R (K) _o(K) method is as follows:

Two subsignals extracted are done respectively the computing of windowing FFT in short-term of 2046, so that signal is converted to frequency-domain analysis by time-domain analysis, definition rectangular window function m (t)=1, then for the frequency-region signal R of this section _eand R (K) _o(K) drawn by following formula:

$R_e\left(K\right)=\underset{t=1}{\overset{2046}{\mathrm{\Σ}}}{r}_e\left(t\right)W_{2046}^{\mathrm{tK}},(K=\mathrm{1,2},\·\·\·,2046)$

$R_o\left(K\right)=\underset{t=1}{\overset{2046}{\mathrm{\Σ}}}{r}_o\left(t\right)W_{2046}^{\mathrm{tK}},(K=\mathrm{1,2},\·\·\·,2046)$

Wherein: refer to the Fast Fourier Transform (FFT) factor, r _et () refers to the even number point signal of extraction, r _ot () refers to the odd point signal of extraction.

3. the anti-interference sparse disposal route of satellite-signal according to claim 1, is characterized in that above-mentioned steps 3) in signal R _e1and R (K) _o1(K) operation carrying out sparse process is as follows: to R _e1and R (K) _o1(K) delivery obtains | R _e1(K) | with | R _o1(K) |; Empirical value φ is set ₂, when | R _e1(K) | be less than empirical value φ ₂time, make R _o1(K) equal zero; When | R _o1(K) | be less than empirical value φ ₂time, make R _e1(K) equal zero; Obtain new frequency-region signal R _e2and R (K) _o2(K), the sparse process of settling signal.

4. the anti-interference sparse disposal route of satellite-signal according to claim 1, is characterized in that above-mentioned steps 4) in, to the frequency-region signal R through sparse process _e2and R (K) _o2(K) carry out inverse fast Fourier transform and obtain new time-domain signal r _e2(t) and r _o2t the method for () is as follows:

After sparse process two frequency-region signal is carried out to the IFFT of the windowing in short-term computing of 2046, definition rectangular window function m (t)=1, then for the time-domain signal r of this section _e2(t) and r _o2t () is drawn by following formula:

$r_{e2}\left(t\right)=\underset{t=1}{\overset{2046}{\mathrm{\Σ}}}{R}_{e2}\left(K\right)W_{2046}^{\mathrm{Kt}},(t=\mathrm{1,2},\·\·\·,2046)$

$r_{o2}\left(t\right)=\underset{K=1}{\overset{2046}{\mathrm{\Σ}}}{R}_{o2}\left(K\right)W_{2046}^{\mathrm{Kt}},(t=\mathrm{1,2},\·\·\·,2046)$

Wherein: refer to the inverse fast Fourier transform factor, R _e2(K) the even number point frequency-region signal through sparse process is referred to, R _o2(K) refer to the odd point frequency-region signal through sparse process, signal is transformed into time domain by frequency domain, obtains new strange signal r _o2(t) and even signal r _e2(t).

5. the anti-interference sparse disposal route of satellite-signal according to claim 1, it is characterized in that above-mentioned steps 5) in, process is caught to above-mentioned signal r` (t) through sparse anti-interference process, thus the method completing the work of catching of satellite navigation signals is as follows: carry out two-dimensional search to the signal through sparse anti-interference process in pseudo-code phase territory and carrier Doppler frequency territory, find out the pseudo-code phase value corresponding to correlation peak and carrier Doppler frequency value, thus determine the pseudo-code phase in input signal and carrier frequency.

6. the anti-interference sparse disposal route of satellite-signal according to claim 1, is characterized in that compatible with COM PASS, GPS, GLONASS and GALILEO tetra-large satellite system.