Second-generation BeiDou B1 frequency band weak signal capturing method

Abstract

The invention belongs to the technical field of satellite communication and especially relates to a rapid high-efficiency signal capturing method for a BeiDou navigation satellite system (BDS). For second-generation BeiDou B1 frequency band weak signals, NH code secondary modulation is carried out on local quantified pseudo-random codes, multi-millisecond coherent integration is carried out on the pseudo-random codes and received signals, a frequency domain code phase searching algorithm based on SFT is realized, and the operation complexity and capturing time of the capturing algorithm are further reduced.

Description

technical field [0001] The invention belongs to the technical field of satellite communication, and in particular relates to a fast and efficient signal acquisition method for a BeiDou Navigation Satellite System (BDS). Background technique [0002] With the implementation of my country's Beidou satellite navigation system, satellite signal acquisition technology has become an important technology in the current and future satellite communication systems. The purpose of BDS-2 signal acquisition is to obtain the carrier frequency and code phase of all visible BDS-2 satellite signals. The search process of carrier frequency and code phase is a two-dimensional search process. If you add the search for different satellites, then the whole acquisition process is a three-dimensional search process. The basis of signal acquisition is the correlation of the ranging code, so for the search, only when the carrier and ranging code signals replicated inside the receiver are consistent ...

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Problems solved by technology

In addition, due to reflection, diffraction and other factors that generate other interference signals, the received signal-to-noise is very low. Under the requirements of low signal-to-noise ratio and high sensitivity, the length of the signal used for correlation calculation must be increased. Unlike traditional GPS signals, Beidou satellite signals use The Neumann-Hoffman code (referred to as NH code) performs secondary code modulation, which brings challenges to the acquisition method of satellite signals while improving the cross-correlation performance. The modulation of NH code makes it possible to generate symbol bit jumps every 1 ms This limits the coherent integration duration of the B1 signal, which seriously affects the acquisition performance of the B1 signal of the second-generation Beidou satellite.

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