The invention discloses a method for acquiring GPS weak signals, which comprises the following steps: carrying out correlation operation for GPS satellite signals received in the set time; ordering the obtained correlation operation results, recording frequency points corresponding to the forward correlation operation results, and recording as once-through operation; repeating the step 1 and the step 2 until the set operation number is reached; listing the frequency points corresponding to the forward correlation operation results of each group of data, counting up the positions of the frequency points and the number of appearance in each position, and obtaining the statistical vectors of the recorded frequency points; if at least one of the statistical vectors is larger than or equal to the threshold value, acquiring successfully; if all the statistical vectors are smaller than the threshold value, acquiring unsuccessfully. For weak signals, because no obvious correlation peaks exist, a general acquiring method can not realize effective acquisition; but for the acquisition algorithm of the invention, even though no largest and second largest correlation peaks and the like exist, the acquisition can success and the amount of calculation is not great.

Method for acquiring GPS weak signals

Weak signal quick capture method on basis of part correlation

The invention discloses a GNSS (Global Navigation Satellite System) receiver cross-correlation interference suppression method based on the subspace projection, and relates to the technical field of communications. The method aims to suppress the cross-correlation interference in a GNSS signal by using carrier frequency information of a strong signal and code phase information of a spread spectrum code, in order to ensure that a GNSS receiver is capable of receiving a weak signal normally when strong and weak satellite signals coexist. The method comprises the steps: completing the capture, tracing and demodulation of N strong signals; before observing and receiving the weak signal, reproducing the carrier frequency information of the observed strong signal and the spread spectrum code information; rebuilding a strong signal matrix by using the observed strong signal information; building a projection matrix of a strong signal subspace by using the obtained strong signal matrix according to a formula (3); calculating a complementary space of the strong signal subspace; projecting a received intermediate frequency signal onto the complementary space to complete the interference suppression calculating, wherein a received signal r is approximately the mixture of the weak signal and the noise. The GNSS receiver cross-correlation interference suppression method based on the subspace projection is suitable for cross-correlation interference suppression in the GNSS receiver.

GNSS (Global Navigation Satellite System) receiver cross-correlation interference suppression method based on subspace projection

The invention discloses a quick recapturing method for a signal of a highly dynamic satellite navigation receiver The quick recapturing method comprises the following steps of: detecting an unlocked passageway of the navigation receiver in each ergodic period; confirming to carry out an ordinary serial search or a quick recapturing search according to the unlocked state of the passageway; confirming a searching frequency point and a searching range in the quick recapturing search; acquiring a pseudo code of the next ergodic period according to a local pseudo code at the present moment; acquiring pseudo code adjusting quantity according to the local pseudo code and the pseudo code of the next ergodic period; and carrying out recapturing according to the pseudo code adjusting quantity When the quick recapturing method is adopted, the navigation signal can be quickly recaptured and positioned after a signal is unlocked according to the characteristics of continuity and stability for the operation of the navigation signal under an actual high-dynamic condition

Quick recapturing method for signal of highly dynamic satellite navigation receiver

The invention provides a fast GPS L2C CM code capturing method. The method comprises the steps of carrying out full-period segmented collapsing on a local code sequence, capturing a data section as long as a local signal from received signal data, carrying out phase search by means of FFT algorithm circular correlation, carrying out theoretical analysis and formula derivation of thermal noise and collapsing noise, obtaining an accurate noise empirical formula by combining with experimental data, providing a reasonable threshold setting scheme to determine a code phase primarily according to the analysis of the signal to noise ratio of the signal, and carrying out time domain coherent processing on the primarily determined code phase after capturing succeeds to obtain a final code phase. According to the fast GPS L2C CM code capturing method, the searching speed of the phase of an L2C signal CM code is improved greatly, the phase of the CM code can be determined fast, and FFT computing amount is reduced greatly.

Fast GPS L2C CM code capturing method

A whole bit acquisition method for GPS weak signals relates to the acquisition treatment of a receiver in GNSS, and solves the problems that the prior software receiver can not forecast the information bit reversal, thereby easily causing the failure of the acquisition, and the better acquisition effect is difficult to achieve by adopting the differential coherent cumulative method. 20 sequences which are compressed into 4096 sampling points are acquired after satellite signals are subjected to the treatments related to frequency mixing, sampling, quantifying and time-domain averaging; the IFFT calculation is carried out after multiplying the 20 sequences with the sequences which are conjugated with the local stored pseudo-code FFT sequences through the FFT calculation; the maximum value which is obtained by the extraction after the mod squaring of the 20 two-dimensional pseudo-code auto-correlation value matrix is compared with a threshold value sigma 1, if the maximum value is larger than the sigma 1, the acquisition is successful; if the maximum value is smaller than the sigma 1, the whole bit algorithm is utilized to seek a peak value of the extracted related values by carrying out the coherent accumulation and the non-coherent accumulation of the 20 two-dimensional pseudo-code auto-correlation value matrix after the information bit reversal, the peak value is compared with the threshold value sigma 2, if the peak value is larger than the sigma 2, the acquisition is successful; and if the peak value is smaller than the sigma 2, the re-acquisition is carried out.

Method for capturing full bit of GPS weak signal

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Method for capturing full bit of GPS weak signal