Design Of Signal Dependent Kernel Functions For Digital Modulated Signals

Abstract

One of the features of a radio monitoring system is the estimation of modulation parameters for digital modulated signals. For low signal-to-noise ratio conditions, time-frequency signal analysis is an attractive method to use. However, analysis of digital modulated signals using existing time-frequency distributions have proven that none of these distributions are suitable for this task. To improve the time-frequency representation of a class of digital modulated signals, a technique for calculating the signal dependent kernel function is derived. The kernel function is derived by minimizing the least-squares error between the calculated and desired time-frequency distributions. Simulations using the bilinear formulation of time-frequency distribution verify the results and the desirable time-frequency distribution is obtained for a given signal class.