Signal Processing Design of Low Probability of Intercept Waveforms via Intersymbol Dither

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 algorithum and a multiplexed bank of equalizer filters determined by an adaptive Least Mean Square algorithum. Numermical simulation is used to demonstrate the bit error rate performance of cooperative receiversand 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.