Wideband adaptive array using the chirp transform
First Claim
1. An array processor for processing signals within a predetermined frequency bandwidth and suppressing interference received by an array of antennas including a main antenna and at least one auxiliary antenna, comprising:
- means coupled to the main antenna for transforming the main antenna signal from the time domain into the frequency domain by a chirp transformation conducted over a time interval of duration T, wherein respective frequency components of the main antenna signal appear in time sequence;
means coupled to the auxiliary antenna for transforming the auxiliary antenna signal from the time domain into the frequency domain by a chirp transformation conducted over a time interval T in synchronism with said chirp transformation of the main antenna signal, wherein respective frequency components of the auxiliary antenna signal appear in time sequence;
means for weighting the transformed auxiliary antenna signal by a time variable coefficient in synchronism with said chirp transformation;
means for combining said transformed main antenna signal and said weighted, transformed auxiliary antenna signal to provide a combined transformed array signal; and
means for transforming the combined array signal to the time domain by an inverse chirp transformation to provide an array processor output.
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Abstract
An adaptive array processor is disclosed for processing the signals from a main antenna and one or more auxiliary antennas to provide suppression of wideband interference. The outputs from the respective antennas are transformed into the frequency domain by synchronized chirp transformers conducted over a transform block length. The transformed auxiliary antenna signal is weighted by time varying, frequency dependent weights which are adaptively determined. The transformed main antenna and weighted auxiliary antenna signals are then combined. The combined signal is then transformed back to the frequency domain by an inverse chirp transformation.
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Citations
34 Claims
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1. An array processor for processing signals within a predetermined frequency bandwidth and suppressing interference received by an array of antennas including a main antenna and at least one auxiliary antenna, comprising:
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means coupled to the main antenna for transforming the main antenna signal from the time domain into the frequency domain by a chirp transformation conducted over a time interval of duration T, wherein respective frequency components of the main antenna signal appear in time sequence; means coupled to the auxiliary antenna for transforming the auxiliary antenna signal from the time domain into the frequency domain by a chirp transformation conducted over a time interval T in synchronism with said chirp transformation of the main antenna signal, wherein respective frequency components of the auxiliary antenna signal appear in time sequence; means for weighting the transformed auxiliary antenna signal by a time variable coefficient in synchronism with said chirp transformation; means for combining said transformed main antenna signal and said weighted, transformed auxiliary antenna signal to provide a combined transformed array signal; and means for transforming the combined array signal to the time domain by an inverse chirp transformation to provide an array processor output. - View Dependent Claims (2, 3, 4, 5, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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6. An adaptive array processor for an array comprising a main antenna and at least one auxiliary antenna for receiving signals within a predetermined frequency bandwidth and suppressing interference therein, comprising:
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a first chirp transformer means coupled to said main antenna for transforming main antenna signals from the time domain into the frequency domain by the chirp transformation performed over a succession of chirp transform block time-domain intervals; a second chirp transformer means coupled to said auxiliary antenna for transforming auxiliary antenna signals from the time domain into the frequency domain by the chirp transformation performed over said succession of chirp transform block time-domain intervals; an auxiliary processor means for providing a sub-band coefficient corresponding to each one of a plurality of predetermined frequency sub-bands comprising said bandwidth, said auxiliary processor means coupled to receive said transformed signals for said second chirp transform means, said auxiliary processor having means for sequentially weighting the output signal from said second chirp transformer means in accordance with said coefficients in synchronism with said chirp transformation to provide an auxiliary processor output signal which is optimized in each frequency subband; means for combining the transformed main antenna signal and the auxiliary processor output signal to provide a combiner output signal; and inverse chirp transformer means for transforming the combiner output signal from the frequency domain to the time domain to provide a processor output. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for processing signals in a predetermined frequency bandwidth received by an array of antennas, including a main antenna and at least one auxiliary antenna, comprising a sequence of the following steps:
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transforming the main antenna signal from the time domain into the frequency domain by a chirp transformation conducted over a time interval of duration T, wherein respective frequency components of the main antenna signal appear in time sequence; transforming the auxiliary antenna signal from the time domain into the frequency domain by a chirp transformation conducted over a time interval of duration T in synchronism with the chirp transformation of the main antenna signal, wherein respective frequency components of the auxiliary antenna signal appear in time sequence; weighting the transformed auxiliary antenna signal by a time variable coefficient in synchronism with said chirp transformation; subtracting from said transformed main antenna signal said weighted, transformed auxiliary antenna signal; and transforming the resultant signals back to the time domain by an inverse chirp transformation to provide a processor output signal. - View Dependent Claims (17, 18, 29, 30, 31, 32, 33, 34)
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Specification