BOC modulating signal capturing method based on overlapped difference circulation coherent integration

Abstract

The invention relates to the field of capturing and processing of a receiver in a global navigation satellite system (GNSS), in particular to a BOC modulating signal capturing method based on overlapped difference circulation coherent integration. The BOC modulating signal capturing method based on overlapped difference circulation coherent integration comprises the steps that an intermediate-frequency signal is received by the receiver to serve as a receiving signal for data processing; a signal obtained after carrier waves are removed is taken as an input signal of four branches; self overlapping is conducted on a data block; the PRN codes of a satellite to be captured and a BOC signal obtained after BOC modulation are generated locally, and fast Fourier transformation is conducted; Fourier inversion is conducted, and a model is solved; multiplication is conducted on the local PRN codes, and Fourier inversion is conducted; subtraction is conducted, and an obtained value and a conjugate value are reserved; the conjugate value obtained through the current branch is multiplied by the same-level value of the next branch. By the adoption of the BOC modulating signal capturing method based on overlapped difference circulation coherent integration, weak signals can be well captured, and the adaptability of the receiver to the weak signals is improved.

Description

technical field [0001] The invention relates to the field of capture processing of receivers in GNSS (Global Satellite Navigation System), in particular to a method for capturing BOC modulated signals based on overlapping differential cyclic coherent integration. Background technique [0002] With the rapid development of satellite navigation technology, the new generation of satellite navigation system (GNSS—Global Navigation Satellite Systems) presents a new situation of multi-level competition and complementary advantages. The satellite navigation system has also moved from independent construction to cooperative development and utilization. In order to achieve compatibility between multiple navigation systems, enable satellite navigation frequency bands to share frequency bands and separate spectrum, and achieve high detection accuracy and performance requirements, the new generation of satellites The navigation signals are all modulated by binary offset carrier (BOC—Bin...

AI Technical Summary

Problems solved by technology

The advantage of this method is that once the main peak is locked, it has high tracking accuracy. The disadvantage is that because it is based on the comparison of the power of the main peak and the peaks on both sides, there will be a high probability of missed detection and false alarm when the signal-to-noise ratio is low. , and once a false lock occurs, the required recovery time is longer, so it is not suitable for real-time occasions

(2) BPSK-like method, this method mainly has two typical representative applications, named "B&F" method and "M&H" method respectively, its core idea is to use the main lobe of BOC modulated signal power spectrum and BPSK modulated signal power Spectrum similar characteristics, realize the unimodal characteristic of BOC autocorrelation function, but this method also has shortcomings and limitations, for example, due to the use of filters, there will be a 3db attenuation for single sideband processing, and for double sideband , there will be an attenuation of 0.5db, and this method also loses the advantage of high-precision tracking performance of BOC modulated signals, so further improvement and optimization are needed

Three signals are processed in parallel. If the maximum value exceeds the threshold, the signal is considered to be captured. The disadvantage of this method is that it is only applicable to BOC(n,n) type signals.

(4) Auto-correlation side-peak cancellation technology (ASPeCT—auto-correlation side-peak cancellation technique), by using the special characteristics between the square of the BOC autocorrelation function and the square of the BOC / PRN cross-correlation function to achieve the purpose of removing side peaks , but this method is only applicable to SinBOC(n,n) type

[0004] At present, the solution to the problem of BOC modulation signal capture is under the condition of strong signal, but for the capture of weak BOC signal, there is basically no one involved, but because the city uses more positioning systems, and in the city The signal will be attenuated to a very weak situation. In this case, the above-mentioned BOC signal capture is basically unusable, so it becomes an inevitable trend to study the weak BOC signal capture algorithm.

Images