Co-channel FM signal/interference canceller
First Claim
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1. A device for removing a dominant FM signal from within a set of input signals occupying the same frequency band, comprising in combination:
- a) FM demodulation means for recovering the modulating signal of a received dominant FM carrier signal;
b) FM modulation means for generating a replica of the received dominant FM carrier signal using the output of said FM demodulation means as the modulating signal;
c) delay means for aligning in time the original signal input to a replica of the dominant FM signal generated by said FM modulation means; and
d) cancellation means for removing the dominant FM signal from a set of input signals occupying the same frequency band;
said cancellation means comprising;
means to demodulate said dominant FM signal to a single spectral line;
means to filter out said spectral line to produce the cross-products of the dominant FM signal and underlying signals; and
means to multiply said signal cross-products with the dominant FM signal again to obtain a signal which contains all of the original underlying signal or signals without the dominant FM signal present.
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Abstract
A combination of two phase-lock loops, and a cancellation circuit are used to remove a dominant FM signal from within a signal environment. The two phase-lock loops together produce a replica of the highest power (i.e. dominant) FM signal. The cancellation circuit uses this replica in a demodulation, notch-filtering, and remodulation process to excise the dominant FM signal, leaving the other signal(s) undisturbed. Potential applications include co-channel FM signal/interference cancellation and optimizing utilization of RF spectrum.
17 Citations
1 Claim
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1. A device for removing a dominant FM signal from within a set of input signals occupying the same frequency band, comprising in combination:
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a) FM demodulation means for recovering the modulating signal of a received dominant FM carrier signal; b) FM modulation means for generating a replica of the received dominant FM carrier signal using the output of said FM demodulation means as the modulating signal; c) delay means for aligning in time the original signal input to a replica of the dominant FM signal generated by said FM modulation means; and d) cancellation means for removing the dominant FM signal from a set of input signals occupying the same frequency band; said cancellation means comprising; means to demodulate said dominant FM signal to a single spectral line; means to filter out said spectral line to produce the cross-products of the dominant FM signal and underlying signals; and means to multiply said signal cross-products with the dominant FM signal again to obtain a signal which contains all of the original underlying signal or signals without the dominant FM signal present.
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Specification
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Current AssigneeGeneral Dynamics Government Systems Corporation (General Dynamics Corporation)
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Original AssigneeGTE Government Systems Corporation (General Dynamics Corporation)
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InventorsSvoboda, Esteban O.
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Primary Examiner(s)Eisenzopf, Reinhard J.
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Assistant Examiner(s)SOBUTKA, PHILIP
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Application NumberUS08/228,060Time in Patent Office1,334 DaysField of Search455/304, 455/302, 455/303, 455/305, 455/306, 455/206, 455/260, 455/126, 455/214, 329/336, 329/327, 329/316, 329/320, 329/325US Class Current455/304CPC Class CodesH04B 1/123 using adaptive balancing or...
