SIGNAL ENERGY DISTRIBUTION IN TIME AND FREQUENCY.
Abstract
The Fourier representation of signals and its relation to the signal structure in time and frequency, and more generally the inherent properties of phase-modulated signals, have received considerable attention in the past. These topics have led to such seemingly unrelated studies as the representation of a signal in a combined time-frequency plane, 'instantaneous power spectra', and the ambiguity function and its transform relations. It is shown in this paper that the studies can be unified by the introduction of the concept of the complex energy density function of a signal. The function is an extension and combination of the one-dimensional energy density functions in time and frequency, the energy density spectrum (the absolute value of psi(f)) squared, and energy density waveform (the absolute value of psi(t)) squared. On the basis of the complex energy density function, the significance of complicated-appearing transform relations is readily understood. The new concept also conveys a good insight into the internal structure of phase-modulated signals. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1967
- Accession Number
- AD0664326
Entities
People
- A. W. Rihaczek
Organizations
- The Aerospace Corporation