Signal Processing Design of Low Probability of Intercept Waveforms via Intersymbol Dither; Master's thesis

摘要

This thesis investigates a modification to Differential Phase Shift Keyed modulation to create a low Probability of Interception/Exploitation communications signal. A Pseudodorandum timing offset is applied to each symbol in the communications stream to intentionally create intersymbol interference that hinders accurate symbol estimation and bit sequence recovery by a non- cooperative receiver. Two cooperative receiver strategies are proposed to mitigate the ISI due to symbol timing offset: a modified minimum Mean Square Error equalization algorithm and a multiplexed bank of equalizer filters determined by an adaptive Least Mean Square algorithm. Numerical simulation is used to demonstrate the bit error rate performance of cooperative receivers and notional non-cooperative receivers. Simulation results suggest that proper selection of pulse of pulse shape and probability distribution of symbol timing offsets produces a waveform that is accurately demonstrated by the proposed cooperative receivers and significantly degrades non-cooperative receiver symbol estimation accuracy.