D.J. Nelson and D.C. Smith (USA)
- Short time Fourier transform, spectralsubtraction, instantaneous frequency, channelized instantaneous frequency, time-frequency representations.
We propose a new linear time-frequency (TF) paradigm, in which the value of a signal at any time is distributed in fre quency. Starting with the short time Fourier transform (STFT) representation of a signal, we apply a morphing process, based on the channelized instantaneous frequency (CIF), to obtain a new TF representation. When applied to a multicomponent signal which has linearly independent components and which satisfies a separability condition, the process produces a TF representation in which the value of each signal component is distributed along the component's instantaneous frequency curve in the time-frequency plane. The method is linear on the span of the signal's compo nents, and cross-terms, which make it difficult for conven tional TF methods to isolate individual components, do not occur. The individual components are effectively isolated in the new representation, and may be recovered by a straight forward integration. We apply the new technique to remove an additive sinusoidal FM interferer from a speech signal, and demonstrate its superiority to either the STFT or stan dard spectral subtraction.
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