High Resolution TimeFrequency Representation of NarrowBand Transient Signals
© April 2000
Introduction
With the advent of very high speed, precision A/D converters, much of the sophisticated signal processing is shifting from the electronic analog domain to digital signal processing algorithms. Today, the acquisition of signals with an upper bandlimit of one Megahertz merely requires basic signal preconditioning electronics, all further processing such as filtering, rateconversions, and signal detection can be applied after the signal has been digitized.
This report puts a focus on a timefrequency method for signal detection. Generally timefrequency processing received much attention in the context of waveletanalysis. However, the timefrequency representation based on a wavelet spectrum is difficult to relate to physical signal properties.
This approach is different. It is based on Fourierspectra. The signal is analyzed to derive a parametric spectral model. A Fourierspectrum can then be computed with arbitrary frequency resolution. The parametric model is calculated on a sample by sample basis. Thus, a sonogram of a signal may be computed with unlimited frequency resolution and a resolution in time as small as , where is the sampling interval.
