Adaptive A/D Converter to Suppress CW Interference in DSPN Spread-Spectrum Communications

The non-Gaussian nature of CW interference is exploited to suppress the CW via the A/D converter following chip demodulation in a direct sequence pseudonoise (DSPN) communication link. The modulation is coherent BPSK. The A/D converter quantizes to 2 bits, sign and magnitude. A scheme of threshold adaptation and postquantization weighting gains great advantage from making very reliable decisions on a relatively small percentage of the demodulated chips. The bit error rate performance in CW interference generally surpasses that of an ideal analog DSPN correlator. The performance in Gaussian noise is within 0.6 dB of ideal analog.