Real time pseudo-code period synchronous technique for non-cooperation low signal-noise ratio direct-sequence spread-spectrum signal

Abstract

A real-time pseudo-code period synchronizing technique which is used for the non-cooperative low signal-to-noise ratio direct sequence spread spectrum signal is specially used for the user recognition, signal interception and danger information analysis, and also can be used for the realization of new generation of spread spectrum communication network and a management mode. The invention directly uses the optimum detecting statistic of the pseudo-code period of the direct spreading signal as a synchronizing facility of the non-cooperative DSSS signal receiver, and facilitates that a novel plan of a non-cooperative receiver which can work in the extraordinary low signal-to-noise ratio can be realized. The core of the plan is that an accurate pseudo-code period synchronizing component without knowing any apriori knowledge of carrier frequency, pseudo-code speed and spread spectrum sequence. Therefore the synchronizing technique is provided on the front end of the receiver and a series of problems for receiving the non-cooperative direct spreading signal in low signal-to-noise can be settled. The technique provided by the invention has the advantages of realizable hardware, high speed for realizing the technique, simple structure and high suitability for FPGA parallel realization. The technique of the invention is a method with high efficiency and practicality.

Description

technical field [0001] A real-time pseudo-code period synchronization technology for non-cooperative low signal-to-noise ratio direct-sequence spread spectrum (DSSS, DSSS for short) signal belongs to the field of communication technology, and is specifically applied to frequency band management, signal interception and distress information analysis, It can also be used in a self-organized sensor network or as a realization of a new generation of spread spectrum communication network. It can accurately and real-time determine the pseudo-code period of the DSSS signal under the condition of unknown carrier frequency, symbol rate and pseudo-code sequence. And the non-cooperative reception of the whole direct spread system can be realized with a new scheme. [0002] DSSS (Direct Sequence Spread Spectrum, referred to as DSSS) signal is to multiply the baseband information sequence with a pseudocode sequence (also referred to as PN code) with a much higher symbol rate, and then tra...

AI Technical Summary

Problems solved by technology

In non-cooperative reception, since various parameters and pseudo codes are unknown, the pseudo code synchronization loop cannot be established

In addition, the estimation accuracy of the existing pseudo-code cycle estimation algorithm is limited, so that in the actual system, as long as the error of the pseudo-code cycle accumulated over several cycles is greater than one chip, it is no longer possible to improve the low signal-to-noise rate by accumulating received data. compare

[0011] Third, the difficulty of accurate carrier frequency estimation and coherent reception

The higher the order of processing, the more unfavorable it is for detection at low SNR. Therefore, for high-order modulation such as QPSK, it is impossible to detect and estimate the carrier frequency at low SNR.

[0012] Due to the above problems, from a practical point of view, there are still many key difficulties in completing the non-cooperative reception of DSSS signals with existing technologies

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