Receiver of wideband digital signal in the presence of a narrow and interfering signal
First Claim
1. A method of discriminating a desired signal having a wide frequency band and including sequential symbols representing digital values, the desired signal being discriminated from a narrow band interfering signal having a carrier frequency in the wide band, the method comprising initially applying both of the signals to a filter so both signals are passed to an output of the filter, responding to the filter output to derive estimates of the values of received symbols of the desired signal, comparing the filter output with the estimated values of the received symbols to derive an error representing signal, and controlling a characteristic of the filter in response to the error representing signal so the filter is adjusted to reject the interfering signal and pass the desired signal.
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Accused Products
Abstract
A desired signal having a wide frequency band and including sequential symbols representing digital values is discriminated from a narrow band interfering signal having a carrier frequency in the wide band by initially applying both signals to a filter so both signals are passed to an output of the filter. In response to the filter output, estimates of the values of received symbols of the desired signal are derived and compared to the filter output to derive an error representing signal. A characteristic of the filter is controlled in response to the error representing signal so the filter is adjusted to reject the interfering signal and pass the desired signal.
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Citations
24 Claims
- 1. A method of discriminating a desired signal having a wide frequency band and including sequential symbols representing digital values, the desired signal being discriminated from a narrow band interfering signal having a carrier frequency in the wide band, the method comprising initially applying both of the signals to a filter so both signals are passed to an output of the filter, responding to the filter output to derive estimates of the values of received symbols of the desired signal, comparing the filter output with the estimated values of the received symbols to derive an error representing signal, and controlling a characteristic of the filter in response to the error representing signal so the filter is adjusted to reject the interfering signal and pass the desired signal.
- 9. Apparatus for receiving wideband emissions from a first geosynchronous satellite in the presence of a narrow band emission from a second geosynchronous satellite having a relatively close arcuate spacing from the first satellite, the wide band and narrow band emissions being capable of having overlapping spectra such that the narrow band can have a carrier frequency that is variable in the spectrum of the wide band, comprising an antenna having a beamwidth such that emissions from the first and second satellites are respectively transduced into first and second simultaneously occurring electrical signals having amplitudes with the same order of magnitude, and an adaptive filter responsive to the first and second electrical signals for attenuating substantially the second -signal relative to the first signal so the first signal as coupled to an output terminal of the filter has an amplitude that can produce a perceptible response in an output device and the second signal as coupled to the output terminal has an insufficient amplitude to produce a perceptible response in the output device even though the carrier frequency is variable in the wide band.
- 21. A method of terrestrially receiving a first electromagnetic wave having a predetermined wide frequency band emitted from a first geosynchronous satellite spaced from a second geosynchronous satellite by a predetermined arc, the second geosynchronous satellite emitting a second electromagnetic wave having (a) a narrower frequency band than the first wave, and (b) a carrier frequency that is variable in the frequency band of the first wave, the first and second waves being simultaneously emitted from the first and second satellites, the method comprising simultaneously transducing the first and second waves into first and second simultaneously derived electrical signals that are substantial replicas of variations of the waves with a receiver including a terrestrial antenna pointed generally at the first satellite and having a beamwidth so the first and second waves are transduced into signals having the same order of magnitude, and responding to said first and second signals to substantially attenuate the second signal relative to the first signal so the first signal is passed to an output device, the output device producing a perceptible output in response to the first signal and failing to produce a perceptible output in response to the second signal or producing an output that does not significantly adversely affect the performance of the output device.
Specification