Pseudo code capturing method and capturing device using multiple antennae of direct sequence spread spectrum system

Abstract

The invention provides a pseudo code capturing method and device using multiple antennae of a direct sequence spread spectrum system. The method comprises the following steps: (1) each antenna uses one capture branch to determine self-adaptive weight vector by combining capture branch output according to the space correlation matrix of the received signal acquired by each antennae; (2) the capture branch output is subjected to weighted sum by using the self-adaptive weight vector in the step (1) so as to output decision statistics; and (3) the captured decision statistics is compared with a threshold to make a decision, if the captured decision statistics is more than or equal to the threshold, a tracking phase is carried out; otherwise, the PN code phase position of a local PN code relatively to the received signal is converted and the above processes are repeatedly carried out. The device comprises an analog digital conversion unit, digital down-conversion unit, a correlator unit, a captured decision statistic calculation unit and a threshold comparison unit. The device has the advantages of simple structure, strong interference resistance, independent decision threshold to signal-to-interference and noise ratio and the like.

Description

technical field [0001] The invention mainly relates to the technical field of direct sequence spread spectrum, in particular to a pseudo code acquisition method and equipment using multiple antennas in a direct sequence spread spectrum system. Background technique [0002] The direct sequence spread spectrum system has good anti-interference and anti-interception performance, and can also be used to realize code division multiple access, ranging and timing, so it has been widely used in communication, positioning and navigation, measurement and control systems, etc. [0003] In a direct-sequence spread spectrum system, if the receiver wants to correctly demodulate the received signal, it must first synchronize the pseudo-random sequence (also called PN code, pseudo-code) in the receiver with the PN sequence of the received signal. This synchronization process is implemented in two steps, namely capturing and tracking. Through the acquisition stage, the timing error between ...

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Problems solved by technology

[0009] Another type of method is to perform beamforming on signals received by multiple antennas during acquisition to suppress interference and improve SINR, such as the literature B.Wang and H.M.Kwon, PN code acquisition using smart antenna for spread-spectrum wireless communications-I[ J], IEEE Trans on Vehicular Technology, 2003, 52(1): 142-149 (B.Wang and H.M.Kwon, Pseudorandom Code Acquisition Using Smart Antennas for Spread Spectrum Wireless Communications, IEEE Transactions on Mobile Technology, 2003, 52(1): 142-149), the normalized least mean square algorithm (NLMS) is used to obtain the weight vector of spatial weighting, and the weight convergence is relatively slow in the adaptive process, and its capture performance is difficult to carry out accurate theoretical analysis

[0010] In modern wireless communication systems, the parameters of the communication channel are generally time-varying, especially in the wireless mobile communication environment, due to the influence of time-varying fading, multipath transmission, interference, etc., the input signal of the receiver and the signal-to-interference-noise ratio will change, this situation puts some new requirements on PN code acquisition, because the best acquisition performance can only be obtained in a small range of signal-to-noise ratio with a fixed specific threshold

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