The interception of spread spectrum waveforms via the amplitude distribution function
W.E. Snelling, E. Geraniotis · 2002
Within the context of unfriendly detection and interception of secure communications, an innovative concept called the amplitude distribution function (ADF) is used to construct a detector that is an enhancement to the radiometer. The ADF is developed and shown to be roughly the average probability distribution of a random process. The significance of ADF is that under most spreading modulations, the ADF is invariant. Modulation invariance suggests that a detector built around the ADF concept can be robust and general purpose. To indirectly estimate the ADF from observations, the amplitude moment statistic (AMS) is defined and used for detecting a sinusoid in stationary Gaussian noise. Detection performance is then analyzed, compared with that of a radiometer, and shown superior for small time-bandwidth products.>