SIXTH ANNUAL
ASAP '98 WORKSHOP

Performance of the
Adaptive Sidelobe Blanker
Detection Algorithm in the
Presence of Signal
Mismatch

 

 

Christ D. Richmond
MIT Lincoln Laboratory
244 Wood Street, Room J-118D
Lexington, MA 02173-9108
tel: (781) 981-5954
email: christ@ll.mit.edu

Abstract Recently a two-dimensional (2-D) adaptive detection algorithm known as the adaptive sidelobe blanker (ASB) was introduced as a means of mitigating the effects of undernulled clutter, clutter discretes, and sidelobe targets in 1-D adaptive matched filter (AMF) detection [1]. A previous study [2] of the 2-D ASB provided closed form expressions for the probabilities of false alarm (PFA) and detection (PD) under both homogeneous and non-homogeneous conditions. Heterogeneous conditions were modeled via a mismatch between the covariance of the training set samples and that of the test cell in an attempt to analyze the algorithm's ability to reject sidelobe breakthroughs. The study, however, presumed perfect knowledge of the target array response vector (signal steering vector). In this presentation we consider the effects of steering vector mismatch under homogeneous complex Gaussian conditions. Closed form expressions for the PD and PFA in the presence of steering vector mismatch are provided for the 2-D ASB algorithm. It is observed that the adaptive cosine estimator (ACE) [3] has the best sidelobe rejection capability and the worst target sensitivity, whereas the AMF has the worst sidelobe rejection capability and the best target sensitivity. The generalized likelihood ratio test (GLRT) has performance falling between the two. The ASB algorithm provides a systematic way of trading off target gain for sidelobe rejection via the appropriate choice of threshold pairs. We likewise compare a 1-D tapered AMF to the untapered 2-D ASB. Both are designed to handle sidelobe breakthroughs, so the comparison is of practical interest.

[1] D.E. Kreithen, A.O. Steinhardt, "Target Detection in Post-STAP Undernulled Clutter," 29th Annual Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, October 29­November 1, 1995.

[2] C.D. Richmond, "Statistical Performance Analysis of the Adaptive Sidelobe Blanker Detection Algorithm," to appear at 31st Annual Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, November 2­5, 1997.

[3] L.T. McWhorter, L.L. Scharf, L.J. Griffiths, "Adaptive Coherence Estimation for Radar Signal Processing," 30th Annual Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, November 3­6, 1996.


 


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