Improvements of Antijam Performance of Spread-Spectrum Systems

The present paper gives theoretical analysis and simulation tests of a proposed external circuit connection for enhancing the performance of spread-spectrum (SS) systems in the presence of continuous wave (CW) interference. This connection is an adaptive notch filter. It consists of a hard limiter, a phase-locked-loop (PLL) tracking the CW interference yielding a first estimate, an adaptive two-quadrature weighted channel, and linear combiner producing a more accurate estimate of the CW interference. The simulation tests of this connection give, in general, performances superior to previous authors´ results for certain ranges of signal-to-noise ratio.