Interception and demodulation of slow frequency-hopped differential phase shift keyed signals using envelope detection and pattern recognition

Abstract

This thesis presents a novel non-coherent wireless communication receiver design for intercepting and demodulating frequency hopping spread spectrum (FHSS) signals. This interception receiver is based upon phase modulation to amplitude modulation conversion (PM to AM), and is specifically designed for demodulating a slow frequency-hopped signal that has differentially encoded phase shift keying (DPSK) modulation. The receiver will also demodulate non-frequency hopped DPSK signals. Matlab(Superscript Trade Mark Symbol) simulations show that if a signal has a signal to noise ratio (SNR) greater than approximately 30 dB, the intercept receiver can demodulate it by using the following: a bank of filters for PM to AM conversion, envelope detectors for each filter in the bank, and a pattern recognition algorithm that processes the envelope detector outputs, combines them, and maps the result into bits. The performance of the receiver is characterized with simulations and analytical calculations.