A simple scheme for adapting time-frequency representations

Current signal-dependent time-frequency representations are block-oriented methods suited only for short-duration signals. The authors propose a simple, computationally efficient technique for creating adaptive time-frequency representations in which a kernel characterized by one free parameter is adapted over time. Time adaptation of the kernal allows continuous updating of the kernel to optimally track changes in signal characteristics. The procedure computes a short-time quality measure (concentration or entropy based) of the time-frequency representation for a range of values of the free parameter and estimates the parameter value, maximizing the quality measure by means of interpolation. Simple examples illustrate the benefits of this technique over fixed-kernel representations