Fast capturing method for non-coherent spread spectrum signal

Abstract

The invention discloses a fast capturing method for a non-coherent spread spectrum signal, and aims to fast and accurate capturing of spread spectrum code phases and Doppler. The method is implementedthrough the following technical scheme: in a spread spectrum receiving system, a pseudo-code generator generates a local spread spectrum code sequence; the local spread spectrum code sequence is sentto a parallel processing unit for performing multipath parallel processing; frequency slot division is carried out according to slot division control information sent by a main control unit; carrierDoppler is compensated; matched filtering, coherent integration, zero-padding FFT and non-coherent integration are carried out sequentially; multi-dimensional peak value search is carried out on a plurality of branch signals; a phase capturing result and a carrier frequency rough estimation result are obtained; the obtained phase capturing result and carrier frequency rough estimation result are sent to the main control unit; the main control unit sends selection control information to a branch selection unit; and a received signal aligned to a phase of the local spread spectrum code sequenceis selected and output to an accurate frequency measurement unit for estimating a carrier frequency of the received signal.

Description

technical field [0001] The invention relates to a capture technology in the field of wireless communication, in particular to a method for capturing the pseudocode phase and carrier frequency of a non-coherent spread spectrum signal in a spread spectrum receiver. Background technique [0002] The spread spectrum communication system has many advantages that other communication systems cannot match, but there is a prerequisite for obtaining these advantages, that is, normal despreading and demodulation must be realized at the receiving end. There are two ways of despreading: correlated despreading and non-correlated despreading, and correlation despreading is usually used in communication systems. In order to realize correlation despreading and demodulation, it is first necessary to realize accurate estimation of code phase and code Doppler of spread spectrum of received signal. The code Doppler frequency shift r is composed of two parts: one part is the code Doppler frequen...

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Problems solved by technology

due to r 2 with f 2 They all change randomly within a certain range and are not correlated. It can be seen that the code Doppler frequency shift r and the carrier Doppler frequency shift f do not satisfy the coherent relationship

[0004] The traditional spread spectrum signal acquisition method only considers the coherence of code Doppler and carrier Doppler. When applied to a spread spectrum system in which code Doppler and carrier Doppler are noncoherent, the noncoherence will lead to reception Chip drift occurs between the signal and the local spreading code, making it difficult to obtain integral gain, resulting in missed or wrong capture

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