Variation law and experimental verification of anti-single-frequency interference ability of underwater acoustic DSSS system with short-period PN sequences
In order to solve the problem of being unable to quantitatively analyze the anti-single-frequency interference performance of the direct sequence spread spectrum(DSSS)communication system with a short-period PN sequence,firstly,the interference components produced by correlation processing of single frequency interference were derivated theoretically.Then,combined with the pro-cessing gain of DSSS system to single frequency interference,and in view of the fact that the spread spectrum sequence period of underwater acoustic system was short,a theoretical expression was put forward for quantitative analysis of the anti-single frequency interference performance of periodic PN sequence DSSS underwater acoustic system.Finally,the correctness of the theoretical expression was verified by simulations and experiments.The results reveal that the interference sequence formed by correlation processing of single frequency interference has a direct current(DC)or sinusoidal distribu-tion;that the effect of single-frequency interference on the system bit error rate is affected by the signal-to-interference ratio,interference frequency offset,phase deviation,and the spreading code structure itself;that the bit error rate varies with the interference phase variation on a regular basis,i.e.,the single-frequency interference with a frequency offset of one time the symbol bandwidth has the greatest influence on the system in all working conditions where the interference frequency offset is an integer multiple of the symbol bandwidth.The concise theoretical expression is extremely useful for quickly predicting the variation law of the anti-single frequency interference performance of a short code underwater acoustic system.
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维普
