Interception of frequency hopped spread spectrum signals

A frequency-hopped, spread-spectrum signal is modeled as a sinusoid that has one of N random, discrete frequencies. Based on this model, the Neyman-Pearson detection theory is used to derive optimum coherent and noncoherent receiver structures. It is shown that the probability of detection, P_D, approaches, the probability of false alarm, P_F, as N gets large. For large N, simple formulas that relate P_D to P_F at a given SNR (signal-to-noise ratio) are given. For a given N, the authors determine the SNR below which interception is impractical as P _D≃P_F. Single-hop and multiple-hop per detection-interval situations are considered