BOC (15, 2.5) modulation method capturing method based on combined related function

Abstract

The invention provides a BOC (15, 2.5) modulation method capturing method based on a combined related function. Firstly, a period of BOC (15, 2.5) intermediate frequency signals lasting for 1 ms are selected as data signals received by a receiver, and a Doppler frequency shift range, a searching stepped frequency and a detection threshold value are selected; secondly, carrier stripping and mixing processing are carried out on the data signals, an I-path signal and a Q-path signal are obtained, and then FFT processing is carried out on the two signals; thirdly, a BOC (15, 2.5) modulation signal generated locally is decomposed into 12 sub-signals, FFT conversion is carried out, a conjugate is taken, and signals on the path I and the path Q are respectively multiplied by the 12 sub-signals, and IFFT conversion is carried out; fourthly, 12 sub-formulas of the needed auxiliary function are stored locally; fifthly, the final result in the third step and the finial result in the fourth step are added correspondingly; sixthly, incoherent integration is carried out on the results of the two paths obtained through processing, and then whether the BOC (15, 2.5) modulation method is captured is judged through comparison with a threshold value gamma. The BOC (15, 2.5) modulation method capturing method based on the combined related function is applied to a BOC (15, 2.5) modulation method of a B3 frequency band in the Compass navigation system.

Description

technical field [0001] The present invention relates to a receiver capture processing method in a GNSS (Global Navigation Satellite System), in particular to the B3 frequency band to be applied in the Compass Navigation Satellite System (Beidou Satellite Navigation System) with a center frequency of 1268.52MHz and a bandwidth of 24MHz , the B3 frequency band will use the BOC (15, 2.5) modulation method. Background technique [0002] The Beidou satellite navigation system is a satellite navigation and positioning system independently developed and constructed by my country. my country built the Beidou regional navigation system (Beidou 1st generation) in 2003. The system can realize multiple functions such as positioning, timing, and messaging in China and surrounding areas. At present, our country is further constructing the system. A regional navigation system has been built covering the entire Asia-Pacific region and can provide navigation services for the entire Asia-Pa...

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, which has two typical representative applications, which are named "B&F" method and "M&H" method respectively. The core idea is to use the BOC modulation signal power spectrum main lobe and BPSK modulation 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 BOC autocorrelation function and the square of BOC / PRN cross-correlation function to achieve the purpose of removing side peaks , but this method is only applicable to SinBOC(n,n) type

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