Study On Narrow-band Interference Suppression Technology In DSSS On Adaptive Filtering And EMD

The communication system of direct sequence spread spectrum has the powerful ability of restraining interference itself, however, by the communication bandwidth limitations, spreading gain, after all, anti-interference ability can reach is limited,it can not ensure conmmunicate fast,safely,and reliably. Especially in the case of strong narrow-band interference, improving the anti-jamming ability of direct sequence spread spectrum communication further is urgently needed to solve. With signal processing technology will increase the system capacity for narrow-band interference suppression.This paper analyse synthetically the technology of anti-jamming ability of direct sequence spread spectrum communication exiting,study the technology of time-domain adaptive prediction, frequency-domain adaptive filtering and so on, summarize the advantages and shortcomings. There are many limitations restrain multi-narrow-band interference based on time-domain LMS adaptive filter, a new technology combined empirical mode decomposition(EMD) with time-domain adaptive filtering for narrowband interference suppression was proposed in this paper.The new technology decompose approximately the direct sequence spread spectrum signal mixed multi-narrow-band interference to many IMF components which contains single interference,then applying the time-domain LMS adaptive filtering to deal with them respectively,the shortcomings are conquered.The simulation results indicate the new technology can restrain multi-narrow-band interference effectively. Specific process is as the follows:1.the traditional methods of restraining narrow-band interference are analysed in this paper. Major research time-domain adaptive suppression techniques, frequency-domain adaptive algorithm for suppression technology for their respective advantages and disadvantages to seek new methods. 2.The background that the EMD, Smooth process,end effect are introduced in detail.the end effect which will lead to distortion of the result of EMD is studied in depth.the existing methods at present time such as mirror extending,network extending, polyfit extending and so on are introduced. On the basis of the analyzing their performances, the method of weighting and median extending are proposed. The simulation results indicated the new method can restrain end effect effectively.3. the principle of the technology combined empirical mode decomposition (EMD) with time-domain adaptive filtering was studied. Experiment respectively on the single audio interference, multi-audio interference,single narrow-band interference and multi-narrow-band interference. The simulation results indicate the new technology conquered the shortcomings of time-domain adaptive filtering, improved successfully system's bit error rate (BER)...