Unequal bandwidth spectral analysis using digital frequency warping
Carlo Braccini, Alan V. Oppenheim · IEEE Transactions on Acoustics Speech and Signal Processing · 1974
The application to unequal bandwidth and vernier spectrum analysis of a technique referred to as digital frequency warping is discussed. In this technique a sequence is transformed in such a way that the Fourier transforms of the original and transformed sequences are related by a nonlinear transformation of the frequency axis. An equal bandwidth analysis carried out on the transformed sequence then corresponds to an unequal bandwidth analysis of the original sequence. A comparison is presented between the bandwidth as a function of frequency for the digital warping technique and proportional bandwidth analysis. An analysis of the effects of finite register length in implementing digital frequency warping is also presented.