Appendix D: Experiments with spread spectrum modulation over dispersive medium
R. Skaug, J. F. Hjelmstad · Institution of Engineering and Technology eBooks · 1985
To provide some experimental data on the useful bandwidth for spread spectrum systems, test equipment consisting of a spread spectrum 2-PSK transmitter was constructed. The receiver consisted of a spread spectrum passive correlator for direct sequence modulation. The passive correlator consists of two lowpass inphase and quadrature filters implemented as two identical digital matched filters constructed to match the spreading code used. The receiver was designed to offer linear phase response to the variable signal bandwidths. The linear phase requirement emerged from the wish to measure the nonlinearities of the ionosphere undistorted by the test equipment.