Interference canceller
First Claim
1. An interference canceller for cancelling interference in a first signal in a communication system that simultaneously processes more than one signal, said interference canceller comprising:
- equalizer means for equalizing the first signal;
compensating signal generating means for generating a compensating signal from a second signal;
first timing recovery means, operatively connected to said equalizer means, for detecting the interference in the equalized first signal by detecting and extracting a beat element of amplitude based on a frequency difference element of a pair of data rates of the first and second signals; and
first control means, operatively connected to said first timing recovery means and said compensating signal generating means, for controlling application of the compensating signal to the first equalized signal based on the detected interference.
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Accused Products
Abstract
In a digital radio transmission system for transmitting independent dual data by using cross polarization, an interference canceller detects cross polarization interference either directly or indirectly. An interference compensating signal is generated and applied to the main signal to cancel the interference element. In a case where no interference element is present, deterioration of cross polarization discrimination from an interference cancelling circuit is prevented by first determining whether an interference element actually exists and applying the interference compensating signal only when it does exist. The interference compensating signal can be attenuated based on the value of interference element so as to prevent undo deterioration of the cross polarization discrimination when the interference element is minimal.
52 Citations
23 Claims
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1. An interference canceller for cancelling interference in a first signal in a communication system that simultaneously processes more than one signal, said interference canceller comprising:
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equalizer means for equalizing the first signal; compensating signal generating means for generating a compensating signal from a second signal; first timing recovery means, operatively connected to said equalizer means, for detecting the interference in the equalized first signal by detecting and extracting a beat element of amplitude based on a frequency difference element of a pair of data rates of the first and second signals; and first control means, operatively connected to said first timing recovery means and said compensating signal generating means, for controlling application of the compensating signal to the first equalized signal based on the detected interference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A compensating signal generator for generating a compensating signal, to compensate for interference in a first signal transmitted with and interfered by a second signal in a communication system, from first and second channels of the second signal, comprising:
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a predetermined number of first channel delay units connected in series on the first channel; a predetermined number of second channel delay units connected in series on the second channel; a predetermined number of first channel tap constant multipliers, the predetermined number being one more than the predetermined number of said first channel delay units, connected in branches from the first channel before and after each of said first channel delay units; a predetermined number of second channel tap constant multipliers, the predetermined number being one more than the predetermined number of said second channel delay units, connected in branches from the second channel before and after each of said second channel delay units; a plurality of adders, operatively connected to said first and second channel tap constant multipliers, for adding outputs from predetermined ones of said first and second channel tap constant multipliers; a plurality of variable attenuators, respectively connected to said adders, for receiving and attenuating outputs from said respective adders; and adder means, operatively connected to said variable attenuators, for receiving and adding outputs from said variable attenuators and outputting the compensating signal. - View Dependent Claims (18, 19)
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20. A method for cancelling interference between first and second signals in a communication system, comprising the steps of:
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(a) equalizing the first signal; (b) generating a compensating signal from the second signal which is transmitted with the first signal; (c) detecting an interference element in the equalized first signal by detecting and extracting a beat element of amplitude based on a frequency difference element of a pair of data rates of the first and second signals; and (d) applying the compensating signal to the first equalized signal based on the detected interference element to cancel interference in the first signal. - View Dependent Claims (21, 22, 23)
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Specification