Use of Instantanteous Bandwidth for Excising AM-FM Jammers in Direct sequence Spread Spectrum Communications Systems

摘要

While spread spectrum systmes are robust to many types of interference. performance can be significantly degraded if the interfernece is strong enough, particularly for wideband interferences. In these situations, various signal sprocesisng methods can be empolyed to remove, or excise, the jammer prior to despreading the received signal, resulting in enhanced perofrmnce. We investigate the effects of amplitude and frequency modulated (AM-FM) jam-mers on the performance of idrect sequence spread spectrum communication systems. We demonstrate that such jammers cuae significant degradation in bit-erro-rate with increasing AM on systmes designed to excise FM jammers only (e,e. systems ith fixed notch-width excison filters). We propose an adaptive techniqeu that utilzies the instatantaneous bandwidth of the jammer, in addition to its instantaneous frequencym, to filter widband AM-FM interfernece instantaneous power of the jammer. Simulations demosntrate additional improvement in system performance for the proposed adaptive technique compared to fixed nothc-width and fixed nothc-depth excision filters.