Fully-digital direct sequence spread spectrum communication system and rapid pseudo code capturing method thereof

Abstract

The invention discloses a fully-digital direct sequence spread spectrum communication system and a rapid pseudo code capturing method thereof. A digital signal is processed by using an FPGA (Field Programmable Gate Array) which comprises a pseudo code capturing module, a sampling signal of an ADC (Analog To Digital Converter) is subjected to frequency mixing with a signal of a local carrier NCO (Numerically Controlled Oscillator) and filtered to obtain a baseband signal, residual carrier Doppler frequency is eliminated from the baseband signal by adopting a differential multiplying mode, thus the phase deviation of a receiving signal and a local pseudo code is further obtained through an FFT (Fast Fourier Transform) algorithm without scanning on a carrier frequency domain; and when the phase deviation of the pseudo code is obtained, a local pseudo code phase is modified and is subjected to correlation degree of dissociation with the receiving signal, and the carrier Doppler frequency is figured out by using the FFT algorithm, and is compensated to a carrier NCO and a pseudo code NCO, thus carrier frequency capturing and pseudo code capturing are realized.

Description

technical field [0001] The invention relates to the fields of radio frequency communication and digital signal processing, in particular to an all-digital direct-sequence spread-spectrum communication system and a pseudo-code rapid acquisition method applied under Doppler conditions. Background technique [0002] Direct sequence spread spectrum communication has gradually become the main technology of modern communication because of its strong anti-interference ability, strong anti-interception ability, confidentiality, and easy realization of multiple access communication. [0003] The principle of spread spectrum communication is to use a high-speed spread spectrum sequence to spread the spectrum of the signal at the transmitter, and use the same spread spectrum code sequence to despread at the receiver to restore the expanded spread spectrum signal to the original signal. The direct sequence spread spectrum method is to directly use the pseudo-noise sequence to modulate t...

AI Technical Summary

Problems solved by technology

The parallel search method is divided into pseudo-code phase parallel search and carrier frequency parallel search, which reduces two-dimensional search to one-dimensional search, reduces the number of searches, and thus reduces the acquisition time. situation, it still takes some time to capture

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