ABSTRACT
The method may be applied to any analog signal S(t) to reconstruct its spectrogram (i.e., the spectrum S(ω) as a function of time) through the continuous optimization of the differential amplication of each individual signal frequency band, so that all the spectral
amplitudes of the various frequency bands are made comparable between them. Once the amplication gains (that in general vary over time) are known, the true S(ω) spectrum can be reconstructed. The possibility to separately vary the gain of each frequency channel allows exploiting the resolution of a single ADC. The change in amplication, through a calibration procedure, optimizes the dynamic resolution of the ADC sampling in all frequency bands without “wasting bits” (Hadji-Abdolhamid and Johns 2003, Haykin 1994, Johns and Martin 1997). This exibility of the method is particularly useful for signals in which the spectral content varies considerably from one frequency band to another. It follows that the actual dynamic resolution of the digitization procedure, achieved by the proposed method, is higher than that of the ADC static procedure.
