Pulse interference cancelling system for spread spectrum signals
First Claim
1. A noise coded communications system, comprising:
- means for generating and transmitting a multiplexed noise coded communications signal formed as a continuous stream of bits;
means for receiving said noise coded communications signal as a continuous stream of bits and any interference signals including a pulse interference signal which forms thereby a combined received signal;
means included in said receiving means for compressing said noise coded communications signal to an impulse; and
means included in said receiving means and coupled to said compressing means for cancelling said pulse interference signal of said combined received signal, said cancelling means comprising first circuit means providing substantially no delay of both the compressed noise coded communications signal and said pulse interference signal of said combined received signal, second circuit means providing a predetermined time delay of both said compressed noise coded communications signal and said pulse interference signal, said delay being of the magnitude to shift said interference pulse signal in phase by 180°
, and third circuit means combining the non-delayed and delayed signals from said first and second circuit means whereby said pulse interference signal is summed with a phase reversed replica of itself which results in a cancellation thereof while an interference free impulse output signal is provided.
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Accused Products
Abstract
Cancellation of pulse interference with no loss in the received level of the desired signal is obtained for a spread spectrum system which utilizes orthogonal multiplexed noise codes which when orthogonally multiplexed, matched filter detected and linearly added, compress to a lobeless impulse. The noise codes are comprised of binary noise codes which compress to a code bit width τ. The pulse interference is eliminated by means of a variable delay line and a linear adder coupled to the output of a linear adder which operates in combination with a pair of matched filters to provide a lobeless impulse signal. The delay line is varied to provide a 180° phase shift for any pulse interference signal which occurs in time coincidence with the lobeless impulse. The original and phase shifted pulse interference signals are added together in the linear adder and in the process cancel one another while leaving the lobeless impulse signal with no reduction in signal amplitude.
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Citations
11 Claims
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1. A noise coded communications system, comprising:
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means for generating and transmitting a multiplexed noise coded communications signal formed as a continuous stream of bits; means for receiving said noise coded communications signal as a continuous stream of bits and any interference signals including a pulse interference signal which forms thereby a combined received signal; means included in said receiving means for compressing said noise coded communications signal to an impulse; and means included in said receiving means and coupled to said compressing means for cancelling said pulse interference signal of said combined received signal, said cancelling means comprising first circuit means providing substantially no delay of both the compressed noise coded communications signal and said pulse interference signal of said combined received signal, second circuit means providing a predetermined time delay of both said compressed noise coded communications signal and said pulse interference signal, said delay being of the magnitude to shift said interference pulse signal in phase by 180°
, and third circuit means combining the non-delayed and delayed signals from said first and second circuit means whereby said pulse interference signal is summed with a phase reversed replica of itself which results in a cancellation thereof while an interference free impulse output signal is provided. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification