A Baseband Code Extraction Method of Underwater Acoustic Two-Phase Modulation Direct Spread Signal

Abstract

The invention discloses an extraction method for a baseband code of a hydroacoustic two-phase modulated direct spread signal. The extraction method includes the steps: firstly, acquiring a data sequence; secondly, detecting and estimating the carrier frequency and the pseudo code rate of the data sequence; thirdly, extracting a baseband signal; fourthly, estimating a phase curve; fifthly, obtaining a primary smooth curve by means of smoothing; sixthly, obtaining a smooth curve by means of smoothing; seventhly, estimating a baseband wave form; eighthly, correcting the baseband wave form; and ninthly, extracting the baseband code from the corrected baseband wave form. The extraction method is capable of acquiring baseband wave form estimation and baseband code extraction by means of baseband signal phase jump after the carrier frequency and the pseudo code rate are estimated, the process is simple, and prior information is less required.

Description

technical field [0001] The invention belongs to the technical field of signal processing, and in particular relates to a method for extracting a baseband code of an underwater acoustic two-phase modulation direct-spread signal. Background technique [0002] In the field of underwater acoustic communication and detection, binary phase shift keying (English full name BinaryPhaseShiftKeying, referred to as BPSK) is a very widely used modulation method, not only for conventional communication methods, but also for direct sequence spread spectrum methods. Its characteristics are Use phase jumps to reflect code changes. In the underwater acoustic system, it is not only necessary to intercept and detect the signal emitted by the enemy, but also to estimate the signal parameters and obtain as much information as possible. For the parameter estimation of phase-modulated direct-spread signals, domestic and foreign literatures have given the estimation methods of carrier frequency, ps...

AI Technical Summary

Problems solved by technology

The method of matrix decomposition needs to know parameters such as pseudo code period and code rate, and the calculation amount is large, which is not conducive to real-time processing; while the neural network method needs to know more prior information, such as pseudo code period, code rate and pseudo code start and end time, and the estimation of the start and end time of the pseudocode is very difficult under non-cooperative conditions

In addition, in the field of underwater acoustics, the underwater acoustic channel is a complex channel that is time-varying, space-varying, and frequency-varying. After channel transmission, the signal amplitude, frequency, and phase are all distorted, and the above methods do not have special features for underwater acoustic channels. sex research

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