THEORY AND APPLICATIONS OF ADAPTIVE CONSTANT-Q DISTRIBUTIONS

A new class of signal adaptive time-frequency representations called t he adaptive-constant-Q distribution (AQD) is introduced, The AQD explo its a priori knowledge about a signal's instantaneous frequency and ba ndwidth to perform signal-dependent smoothing of the Wigner distributi on. The objective is to achieve a good tradeoff between reducing varia nce and preserving resolution by means of time-frequency dependent smo othing (specifically for use in medical Doppler ultrasound), A numeric al, alias-free implementation of the AQD is presented. Deterministic, multicomponent signals as well as synthetic Doppler ultrasound signals were analyzed with the AQD, The performance of the AQD was compared w ith the power spectrogram, the exponential distribution, and the adapt ive optimum kernel representation as well as with theory. The error wa s consistently lowest for the AQD, In conclusion, a new signal adaptiv e class of time-frequency distributions has been developed, and its po tential in nonstationary signal analysis has been demonstrated.