Adaptive interference canceller
First Claim
1. In a dual polarized radar system for transmitting a signal in a predetermined polarization plane, receiving cross-polar and like-polar reflected signals, and detecting said cross-polar signal in the presence of said like-polar signal, wherein said cross-polar signal contains an interference component in the form of a variable gain version of said like-polar signal, an adaptive interference canceller, comprising:
- (a) an adaptive filter with a self-adjusting impulse response for filtering said like-polar signal and in response generating an adaptive weighted version of said like-polar signal; and
(b) means for subtracting said adaptive weighted like-polar signal from said cross-polar signal and in response generating an output signal corresponding to said cross-polar signal with said interference component cancelled therefrom.
1 Assignment
0 Petitions
Accused Products
Abstract
An adaptive interference canceller for use in a dual polarized radar system for receiving cross-polar and like-polar signals and generating an output signal corresponding to the received cross-polar signal with a like-polar interfering component cancelled therefrom. A modified adaptive filter is provided with a self-adjusting impulse response conforming to a least means square adjustment cancelling the influence of the like-polar signal, which is generally much stronger on the cross-point signal. The resulting output has a high target-to-clutter ratio and therefor a high probability of detection.
40 Citations
11 Claims
-
1. In a dual polarized radar system for transmitting a signal in a predetermined polarization plane, receiving cross-polar and like-polar reflected signals, and detecting said cross-polar signal in the presence of said like-polar signal, wherein said cross-polar signal contains an interference component in the form of a variable gain version of said like-polar signal, an adaptive interference canceller, comprising:
-
(a) an adaptive filter with a self-adjusting impulse response for filtering said like-polar signal and in response generating an adaptive weighted version of said like-polar signal; and (b) means for subtracting said adaptive weighted like-polar signal from said cross-polar signal and in response generating an output signal corresponding to said cross-polar signal with said interference component cancelled therefrom. - View Dependent Claims (2, 3, 4)
-
-
5. A dual polarized radar system for receiving a first polarized signal Yhv and a second orthogonal polarized signal Xhh, said first signal Yhv containing a variable interference component of said second signal Xhh, and in response generating an output signal corresponding to said first signal Yhv with said interference component substantially cancelled therefrom, comprising:
-
(a) a first antenna for receiving said first signal Yhv ; (b) a second antenna for receiving said second signal Xhh ; (c) means for converting said first and second signals Yhv and Xhh into respective first and second analog baseband video signals dhv (t) and uhh (t); (d) an adaptive filter for receiving said second baseband video signal uhh (t) and said output signal ehv (t) and in response generating an adaptive weight adjustment signal w(t) in accordance with the equation ##EQU4## wherein w(o) is an initial condition constant and μ
is an adaptation coefficient conforming to the relation ##EQU5## wherein α
.sub.μ
2 is the power of second baseband video signal uhh (t);(e) means for multiplying said second baseband video signal uhh (t) by said adaptive weight adjustment signal w(t) and in response generating an adaptive weight adjusted video signal w(t) uhh (t); and (f) means for subtracting said adaptive weight adjusted signal from said first baseband video signal dhv (t) and in response generating said output signal in the form ehv (t)=dhv (t)-w(t).uhh (t). - View Dependent Claims (7, 8)
-
-
6. A dual polarized radar system for receiving a first polarized signal Yhv and a second orthogonal polarized signal Xhh, said first signal Yhv containing a variable interference component of said second signal Xhh, and in response generating an output signal corresponding to said first signal Yhv with said interface component substantially cancelled therefrom, comprising:
-
(a) a first antenna for receiving said first signal Yhv, (b) a second antenna for receiving said second signal Xhh ; (c) means for converting said first and second signals Yhv and Xhh into respective first and second baseband video signals dhv (h) and uhh (u); (d) an adaptive filter for receiving said second baseband digital video signal uhh (t) and said output signal ehv (n) and in response generating an adaptive digital filter tap weight w(n) in accordance with the difference equation
space="preserve" listing-type="equation">w(n+1)=w(n)=μ
u.sub.hh (u).e.sub.hv (n),wherein μ
, is an adaptation constant;(e) means for multiplying said second baseband video signal uhh (n) by said adaptive digital filter tap weight w(n) and in response generating an adaptive weight adjusted video signal w(n).uhh (n); and (f) means for subtracting said adaptive weight adjusted video signal from said first baseband digital video signal and in response generating said output signal in the form ehv (n)=dhv (n)-w(n).uhh (n). - View Dependent Claims (9)
-
-
10. A dual polarized radar system for transmitting a signal in a predetermined polarization plane and detecting a first signal which is cross-polar relative to said predetermined polarization plane, said first signal being detected in the presence of a second signal which is like-polar relative to said predetermined polarization plane, wherein said first signal includes a variable interference component of said second signal, comprising:
-
(a) a first antenna oriented to receive said first signal; (b) a second antenna oriented to receive said second signal; and (c) an adaptive interference canceller connected to said first antenna and said second antenna for filtering said first and second signals in accordance with a self-adjusting impulse response, and in response generating an output signal in the form of said first signal with said orthogonal variable interference component of said second signal substantially cancelled therefrom. - View Dependent Claims (11)
-
Specification