Detection and estimation of non-Gaussian signals
Summary
Adaptive detection is important for modern radar systems which are tasked
to operate in non homogeneous and non stationary environment. Consider
the case of a radar tasked of surveillance in littoral environment. The
radar will receive N reflections from the ground, the sea surface and,
possibly, from clouds-rain. The clutter intensity may vary of several tens
of dBs from ground to sea; the spectral characteristics of clutter will
also change in terms of Doppler mean values and Doppler spectrum shape.
Moreover, the probability density function of the scattered echoes may
change say from a well-shaped bell (e.g., Gaussian pdf) to a long-tail
curve (e.g., K pdf). Other sources of disturbance are the EM interferences
(EMI) from close EM apparatuses (radio taxi, tv, radio stations, radar,
etc.) and intentional EM interferences; the latter being present in surveillance
radar for defence systems. In all these cases, the radar should be equipped
with a processing scheme which will adaptively estimate in interference
characteristic and properly react to selectively suppress them.
The detection scheme should also maintain a constant level of false
alarms. Adaptivity to interference parameters and constant false alarm
rate (CFAR) behavior are obtained if enough independent samples of intereference
echoes are available; let's say from 2 to 5 times the number of degrees
of freedom of adaptive radar. This will impose constraints on the radar;
e.g., range cell duration, time-on-target, etc.
To summarize, a successful modern detection scheme should encompass
the features of: (a) being adaptive to the interference spectral density
and, more in general, to the pdf of interference, (b) to maintain CFAR
conditions, and (c) to have a relatively simple processing scheme. While
adaptive radar detection against Gaussian clutter was largely investigated
in the past, the same detection problem against a background of correlated
non-Gaussian clutter has been investigated only recently.
Research topics:
Coherent detction of radar targets in non-Gaussian environment
Estimation of signal and disturbance parameters: algorithms and variance
bounds
Sub-optimum detection in a mixture of K-distributed clutter and Gaussian
disturbance
Constant false alarm rate (CFAR) adaptive detection in non-Gaussian
environment
Publications
- F. Gini, "Sub-optimum Coherent Radar Detection in a Mixture of
K-Distributed and Gaussian Clutter," IEE Proceedings Part-F,
(vol. 144, No.1, pp. 39-48, February 1997.
- F. Gini, "A Cumulant-Based Adaptive Technique for Coherent Radar
Detection in a Mixture of K-Distributed Clutter and Gaussian Disturbance,"
IEEE Trans. on Signal Processing , (to appear, 1997).
- F. Gini and M.V. Greco, "Variance Bounds for Parameter Estimation
in Correlated Non-Gaussian Clutter, "Proceedings of the 1997 National
Radar Conference, Syracuse, NY, USA, May 1997 (to appear).
- A. Farina, F. Gini, M.V. Greco and P. Lee, "Improvement Factor
for Real Sea-Clutter Doppler Frequency Spectra"IEE Proceedings
Part-F, vol.143, No 5, pp. 341-344, October 1996
- A. Farina, F. Gini, M.V. Greco, K.J. Sangston, "Optimum and Sub-Optimum
Coherent Radar Detection in Compound Gaussian Clutter: A Data-Dependent
Threshold Interpetation," Proceedings of the IEEE National RADAR
Conference, Ann Arbor, Michigan, USA, May 1996.
- A. Farina, F. Gini, M.V. Greco, F. Lombardini, P. Lombardo, K.J. Sangston,
L. Verrazzani, "Radar Detection of Targets: New Theoretical Findings
and Results by Processing Recorded Live Data," Proceedings of the
1996 CIE International Conference of Radar (invited paper), Beijing,
P.R. China, 8th-10th October 1996, pp.5-12.
- F. Gini, M.V. Greco, L. Verrazzani, "Detection Problem in Mixed
Clutter Environment as a Gaussian Problem by Adaptive Pre-Processing,"
Electronics Letters, vol.31, No.14, pp. 1189-1190, July 1995.
- A. Farina, F. Gini, M.V. Greco, P. Lombardo, "Coherent Radar Detection
of Targets Against a Combination of K-Distributed and Gaussian Clutter,
" Proceedings of the IEEE International RADAR Conference,
Washington,
U.S.A., May 1995.
- F. Gini, L. Verrazzani, "A HOS Technique for Coherent Radar Detection
in Mixed Clutter Environment, " Proceedings of the IEEE Workshop
on Nonlinear Signal and Image Processing, Neos Marmaras, Halkidiki,
Greece, June 1995.
- M.V. Greco, F. Gini, A. Farina, P. Lombardo, "Coherent Radar Detection
of Signals with Unknown Parameters Against a Combination of K-Distributed
and Gaussian Clutter," Proceedings of the 15th GRETSI Symposium
on signal and Image Processing, Juan-Les-Pins, France, September 1995.
- F. Gini, F. Lombardini, "A Novel Linear-Quadratic Technique for
Coherent Radar Detection in Mixed Clutter Environment," Proceedings
of the 25th European Microwave Conference 1995, Bologna, Italy, September
1995.
Contact persons