Nonlinear Chirp Pulse Excitation for the Fast Impedance Spectroscopy

Abstract

Wideband excitation is used to perform the fast spectroscopy – to cover the wide frequency range within short timeframe. Power spectrum of the chirp excitation pulse can cover tailored frequency range within given duration in the time domain. Linear chirp is a well-known wideband excitation waveform, where the instantaneous frequency varies linearly with time. Chirps with nonlinear relationship between time and frequency are also well known. This group of waveforms shape the power spectrum differently from its linear counterpart. The paper describes the results of the study of spectral properties of the nonlinearly modulated chirp signals, where the frequency of the signal varies according to multi-slope nonlinear relationship over the time. The advantage of this type of chirp signals is that the power spectrum of these signals has substantially steeper slope above the cut-off frequency, compared to its common linear and nonlinear counterparts. Ill. 7, bibl. 9 (in English; abstracts in English, Russian and Lithuanian).