Sidelobe canceller with correlation signal weight sampling during transient
First Claim
Patent Images
1. In a canceller:
- a) a main signal transmission channel having an output terminal and an input terminal coupled to receive a signal which may include both desired and undesired signal content;
b) an auxiliary signal transmission channel coupled to receive a signal including primarily said undesired signal;
c) a cancellation loop including means responsive to said main and auxiliary channel signals for generating a cross correlation signal, and means for weighting said auxiliary channel signal in accordance with said cross correlation-signal to thus generate a correction signal,d) means for subtracting said correction signal from said main channel signal thereby to reduce its undesired signal content to a steady state level reached a predetermined period of time after application of such undesired signal to the cancellation loop; and
e) sample-hold switch means including switch actuator means operable initially to close said cancellation loop to enable application of said undesired signal into the loop and operable after a time interval substantially shorter than said predetermined time period to open said cancellation loop and to hold the cross correlation signal then present in the loop, whereby an optimized value of said correlation signal may thus be derived and the auxiliary channel signal weighted in accordance therewith.
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Abstract
An intermediate frequency sidelobe canceller of the kind including a cancellation loop and switch means for sampling and holding correlation weights present in the loop, affording enhanced cancellation and reduced loop lock-on time. This capability is achieved by provision of means for control of the sample-hold switch means so as to limit duration of the sampling interval to an optimum value substantially shorter than the loop stabilization time. Such shorter sampling interval may be either of fixed duration or adaptively controlled in response to one or more loop operating parameters.
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Citations
7 Claims
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1. In a canceller:
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a) a main signal transmission channel having an output terminal and an input terminal coupled to receive a signal which may include both desired and undesired signal content; b) an auxiliary signal transmission channel coupled to receive a signal including primarily said undesired signal; c) a cancellation loop including means responsive to said main and auxiliary channel signals for generating a cross correlation signal, and means for weighting said auxiliary channel signal in accordance with said cross correlation-signal to thus generate a correction signal, d) means for subtracting said correction signal from said main channel signal thereby to reduce its undesired signal content to a steady state level reached a predetermined period of time after application of such undesired signal to the cancellation loop; and e) sample-hold switch means including switch actuator means operable initially to close said cancellation loop to enable application of said undesired signal into the loop and operable after a time interval substantially shorter than said predetermined time period to open said cancellation loop and to hold the cross correlation signal then present in the loop, whereby an optimized value of said correlation signal may thus be derived and the auxiliary channel signal weighted in accordance therewith. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification