Abstract: The narrow band interference suppression performance of adaptive 2 nd -order IIR, 3-coefficient-FIR and 5-coefficient-FIR notch filters are investigated for direct-sequence spread spectrum (DS-SS) communication systems through computer simulation. The feasibility of constructing a DS-SS system with narrow band interference suppression capability of 60dB is studied in detail. It is found that combined with a pulse-shaping filter and an RS(255,223) code, a DS-SS system with processing gain of 1023 and the 2nd-order IIR notch filter can provide the narrow band interference suppression capability of 60dB at SNR of -10dB and BER of 10 -6 ; but the same DS-SS systems with the 3-coefficient-FIR or 5-coefficient-FIR IIR notch filters are not able to provide the capability.

Key words: IIR notch filter, FIR notch filter, Spread spectrum, Narrow band interference, Bit error rate (BER)