Title
On Computing Amplitude, Phase, and Frequency Modulations Using a Vector Interpretation of the Analytic Signal
Abstract
The amplitude-modulation (AM) and phase-modulation (PM) of an amplitude-modulated frequency-modulated (AM-FM) signal are defined as the modulus and phase angle, respectively, of the analytic signal (AS). The FM is defined as the derivative of the PM. However, this standard definition results in a PM with jump discontinuities in cases when the AM index exceeds unity, resulting in an FM that contains impulses. We propose a new approach to define smooth AM, PM, and FM for the AS, where the PM is computed as the solution to an optimization problem based on a vector interpretation of the AS. Our approach is directly linked to the fractional Hilbert transform (FrHT) and leads to an eigenvalue problem. The resulting PM and AM are shown to be smooth, and in particular, the AM turns out to be bipolar. We show an equivalence of the eigenvalue formulation to the square of the AS, and arrive at a simple method to compute the smooth PM. Some examples on synthesized and real signals are provided to validate the theoretical calculations.
Year
DOI
Venue
2013
10.1109/LSP.2013.2284963
Signal Processing Letters, IEEE
Keywords
Field
DocType
Hilbert transforms,amplitude modulation,eigenvalues and eigenfunctions,frequency modulation,phase modulation,amplitude-modulated frequency-modulated signal,analytic signal,eigenvalue problem,fractional Hilbert transform,frequency modulations,phase modulations,vector interpretation,Amplitude modulation,analytic signal,fractional hilbert transform,frequency modulation,phase modulation,squared analytic signal
Signal processing,Analytic signal,Mathematical optimization,Mathematical analysis,Amplitude modulation,Frequency modulation,Hilbert transform,Amplitude,Hilbert spectral analysis,Mathematics,Eigenvalues and eigenvectors
Journal
Volume
Issue
ISSN
20
12
1070-9908
Citations 
PageRank 
References 
1
0.37
6
Authors
2
Name
Order
Citations
PageRank
Arun Venkitaraman1226.90
Chandra Sekhar Seelamantula2487.95