A DSP technique that transforms a digital signal by warping the frequency axis is discussed. The technique corresponds to a mapping of the samples in the z-domain such that they are unevenly spaced around the unit circle. A spectral warping network has the property that a timeshifted impulse function is transformed into a chirp function. This can have useful applications in the analysis of the device-under-test frequency response in electronic testing of analogue and mixed-signal circuits/systems.