Related Experiment Video
Updated: Aug 11, 2026

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
A high resolution approach to estimating time-frequency spectra and their amplitudes
Hengliang Wang1, Kin Siu, Kihwan Ju
1Department of Biomedical Engineering, State University of New York, Stony Brook, NY 11794-8181, USA.
Abstract:
A high resolution approach to estimating time-frequency spectra (TFS) and associated amplitudes via the use of variable frequency complex demodulation (VFCDM) is presented. This is a two-step procedure in which the previously developed time-varying optimal parameter search (TVOPS) technique is used to obtain TFS, followed by using the VFCDM to obtain even greater TFS resolution and instantaneous amplitudes associated with only the specific frequencies of interest. This combinational use of the TVOPS and the VFCDM is termed the TVOPS-VFCDM. Simulation examples are provided to demonstrate the performance of the TVOPS-VFCDM for high resolution TFS as well as instantaneous amplitude estimation. The simulation results show that the TVOPS-VFCDM approach provides the highest resolution and most accurate amplitude estimates when compared to the smoothed pseudo Wigner-Ville, continuous wavelet transform and Hilbert-Huang transform methods. Application of the TVOPS-VFCDM to renal blood flow data indicates some promise of a quantitative approach to understanding the dynamics of renal autoregulatory mechanisms as well as a possible approach to quantitatively discriminating between different strains of rats.
Related Concept Videos
Discrete Fourier Transform
Aliasing
If the sampling frequency is below the Nyquist rate, these replicas overlap, preventing the original signal...
Discrete-Time Fourier Series
For a discrete-time periodic signal x[n]...
Fast Fourier Transform
The computational efficiency of the FFT becomes...
Relation of DFT to z-Transform
To understand how the DFT works, it's helpful to consider the z-transform, which is a method for representing discrete sequences in the complex frequency domain. The z-transform involves summing the terms of...
Sampling Theorem

