Coherent detection using matched filter enhanced spread spectrum demodulation

摘要

A spread-spectrum-phase-locked-loop apparatus and method for coherent detection without a pilot channel. The system comprises symbol- matched means, a voltage-controlled oscillator (VCO), a first product device, a second product device, a third product device, a fourth product device, a first combiner, a second combiner, and a fifth product device. The method comprises the steps of despreading, from a received spread- spectrum signal, an in-phase component and a quadrature-phase component of a symbol sequence signal using the symbol-matched means. The first and second product devices multiply the despread in-phase component by the VCO-cosine and the VCO-sine signals, respectively, to generate a first and a second product signal. The third and fourth product devices multiply the despread quadrature-phase component by the VCO-sine and the VCO-cosine signals, respectively, to generate a third and a fourth product signal. The first combiner combines the first and third product signals to generate a first combined signal. The second combiner combines the second and fourth product signals to generate a second combined signal. The fifth product device multiplies the first and second combined signals to generate an error signal, responsive to which the VCO adjusts the sine and cosine signal levels.