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.

The present work gives a proposed method of sampling speech signals with a nonuniform sampling rate according to the magnitude of the slope of the signal, provided that the average sampling rate satisfies Shannon's requirements. With this proposed method, the quality of the reconstructed speech signal is improved. Experimental results have been compared with those obtained mathematically, and satisfactory agreement is indicated.