A Direct Sequence Spread Spectrum Modulation Method for Suppressing Multipath Interference in Underwater Acoustic Communication

Abstract

The invention provides a direct sequence spread spectrum modulation method for suppressing multipath interference in underwater acoustic communication. According to the direct sequence spread spectrum modulation method, a complementary sequence pair is introduced to underwater acoustic communication as a pseudo-random sequence of direct sequence spread spectrum modulation, better multipath suppression capability than that of an ordinary finite-length random sequence is achieved by using an ideal correlation function constructed in a zero correlation window, and multipath interference in underwater acoustic spread spectrum communication can be suppressed completely. According to the actual need, a pseudo-random sequence of direct sequence spread spectrum modulation can be constructed by combining two types of 'complementary sequence' pairs. By adopting a time-division orthogonal combination mode, the emission duty ratio can be reduced, and an effect of power amplifier cooling can be achieved. A signal is not sensitive to carrier phase when demodulated in an orthogonal mode, and no precise carrier phase synchronization is needed. The efficiency of information transmission by a carrier phase orthogonal combination mode is consistent with spread spectrum modulation of ordinary m sequences, Gold sequences and other pseudo-random sequences. The method has high demodulation bit error rate at high signal-to-noise ratio.

Description

technical field [0001] The invention belongs to the technical field of underwater acoustic spread spectrum communication, in particular to a direct sequence spread spectrum modulation method for suppressing multipath interference in underwater acoustic communication. Background technique [0002] In underwater acoustic communication, the inter-symbol interference (ISI) caused by the multipath effect is the main reason for limiting the information transmission rate. In this regard, the use of direct sequence spread spectrum modulation can not only increase the transmission distance of the signal, but also have a strong inhibitory effect on multi-path signals with a delay greater than one spread spectrum chip according to the sharp autocorrelation characteristics of the PRN code. Therefore, underwater acoustic communication based on DSSS modulation scheme has been extensively studied. In DSSS modulation technology, commonly used spread spectrum codes include m-sequence, Gold ...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a direct sequence spread spectrum modulation method for suppressing multi-path interference in underwater acoustic communication in order to solve the technical problem that the existing direct sequence spread spectrum modulation method cannot completely suppress multi-path interference in underwater acoustic communication, The direct sequence spread spectrum modulation method uses the complementary sequence pair as the pseudo-random sequence of the direct sequence spread spectrum modulation, introduces underwater acoustic communication, and uses the ideal correlation function in the zero correlation window constructed by it to achieve better performance than ordinary finite-length random sequences. multipath suppression

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