Signal analysis by means of time-frequency (Wigner-type) distributions -- Applications to sonar and radar echoes
- Naval Surface Warfare Center, Silver Spring, MD (United States). Carderock Div.
- National Defense Research Establishment, Stockholm (Sweden)
Time series data have been traditionally analyzed in either the time or the frequency domains. For signals with a time-varying frequency content, the combined time-frequency (TF) representations, based on the Cohen class of (generalized) Wigner distributions (WD`s) offer a powerful analysis tool. Using them, it is possible to: (1) trace the time-evolution of the resonance features usually present in a standard sonar cross section (SCS), or in a radar cross section (RCS) and (2) extract target information that may be difficult to even notice in an ordinary SCS or RCS. After a brief review of the fundamental properties of the WD, the authors discuss ways to reduce or suppress the cross term interference that appears in the WD of multicomponent systems. These points are illustrated with a variety of three-dimensional (3-D) plots of Wigner and pseudo-Wigner distributions (PWD), in which the strength of the distribution is depicted as the height of a Wigner surface with height scales measured by various color shades or pseudocolors. The authors also review studies they have made of the echoes returned by conducting or dielectric targets in the atmosphere, when they are illuminated by broadband radar pings. A TF domain analysis of these impulse radar returns demonstrates their superior informative content. These plots allow the identification of targets in an easier and clearer fashion than by the conventional RCS of narrowband systems. The authors show computed and measured plots of WD and PWD of various types of aircraft to illustrate the classification advantages of the approach at any aspect angle. They also show analogous results for metallic objects buried underground, in dielectric media, at various depths.
- OSTI ID:
- 417946
- Journal Information:
- Proceedings of the IEEE, Vol. 84, Issue 9; Other Information: PBD: Sep 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Radar and sonar probing of rocks
CHIRP-Like Signals: Estimation, Detection and Processing A Sequential Model-Based Approach