Narrowband Interference Suppression in Spread Spectrum Communication Systems

Of significant interest to the United States military is the ability of an enemy to deny or disrupt the operation of the Global Positioning System. To combat this threat the GPS JPO initiated the Tactical GPS AntiJam Technology project, which yielded a prototype Digital Excision Filter (DEF) to remove narrowband jammers. This research describes the work performed to get the DEF hardware operational and extends the previous research performed in this area. Comdisco\u27s Signal Processing Worksystem was used to examine the effect of the DEF on the probability of bit error. This research uses peak to average correlation value, probability of bit error, and percent jammer power removed to examine the performance of the DEF. Fourteen jamming scenarios are examined using CW, pulsed CW, and broadband noise jammers. The DEF effectively rejected all of the jammers except the broadband noise jammer. In scenarios other than the broadband noise jammer, the DEF removed over 98% of the jammer power. The bit error rate curves show that the DEF significantly enhanced the performance of the system in extreme jamming environments. The results presented in this research show that the DEF is a viable, robust option to remove narrowband interference