Interference cancellation system for interference signals received with differing phases
First Claim
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1. An interference cancellation system for connection to a radio receiver system having a receiver antenna, a receiver and a receiver transmission line electrically coupling the receiver antenna to the receiver, the interference cancellation system comprising:
- an auxiliary antenna for receiving at least first and second interfering signals, the auxiliary antenna providing a reference signal corresponding to the first and second interfering signals received by the auxiliary antenna;
a first directional coupler, the reference signal being provided to the first directional coupler, the first directional coupler having first and second outputs and respectively providing thereon first and second output signals each corresponding to the reference signal;
a second directional coupler, the second directional coupler being electrically coupled to the receiver transmission line, the second directional coupler having an output and providing thereon a sample signal corresponding to at least the first and second interfering signals and a desired signal received by the receiver antenna;
a synchronous detector, the synchronous detector having at least two inputs respectively electrically coupled to the first and second directional couplers and being responsive to the second output signal of the first coupler and the sample signal of the second coupler, the synchronous detector comparing the first coupler second output signal and the sample signal and providing at least one detector output signal in response thereto;
a signal controller, the signal controller having a first input electrically coupled to the first directional coupler and being responsive to the first output signal of the first coupler, and at least a second input electrically coupled to the synchronous detector, the signal controller having an output and providing thereon a cancellation signal in response to the detector output signal; and
a subtractor, the subtractor being electrically coupled to the receiver transmission line and being further electrically coupled to the signal controller, the subtractor having an input on which is provided the cancellation signal, the subtractor effectively injecting the cancellation signal onto the receiver transmission line carrying the received interfering and desired signals, the cancellation signal injected into the receiver transmission line being equal in amplitude and opposite in phase to at least one of the first and second interfering signals received by the receiver antenna and carried by the receiver transmission line so as to cancel at least the one interfering signal on the receiver line;
the auxiliary antenna having a non-zero phase relationship for the first and second interfering signals relative to the receiver antenna and thereby introducing a phase difference between the first and second signals relative to the receiver antenna;
the auxiliary antenna being spaced apart from the receiver antenna a predetermined distance such that the first and second interfering signals are received by the auxiliary antenna and the receiver antenna with a phase difference which is equal and opposite to that which is introduced by the auxiliary antenna, whereby the first and second signals are received in the same phase in the interference cancellation system relative to the receiver antenna.
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Abstract
An interference cancellation system for cancelling at least two interfering signals received simultaneously and which is adapted to be connected to a radio receiver system having a receiver antenna, a receiver and a receiver transmission line interconnecting the receiver antenna and the receiver includes an auxiliary antenna, a first directional coupler connected to the auxiliary antenna, a second directional coupler connected to the receiver transmission line, a synchronous detector connected to the first and second directional couplers, a signal controller connected the synchronous detector and a subtractor connected to the receiver transmission line and to the signal controller. The auxiliary antenna has a non-zero phase relationship for the two interferring signals relative to the receiver antenna. The auxiliary antenna is spaced apart from the receiver antenna a predetermined distance so that the two interfering signals are received by the two antennas with a phase difference which is equal and opposite to that which is introduced by the auxiliary antenna. As a result, the two interfering signals are received in the interference cancellation system in the same phase relative to the receiver antenna.
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Citations
2 Claims
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1. An interference cancellation system for connection to a radio receiver system having a receiver antenna, a receiver and a receiver transmission line electrically coupling the receiver antenna to the receiver, the interference cancellation system comprising:
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an auxiliary antenna for receiving at least first and second interfering signals, the auxiliary antenna providing a reference signal corresponding to the first and second interfering signals received by the auxiliary antenna; a first directional coupler, the reference signal being provided to the first directional coupler, the first directional coupler having first and second outputs and respectively providing thereon first and second output signals each corresponding to the reference signal; a second directional coupler, the second directional coupler being electrically coupled to the receiver transmission line, the second directional coupler having an output and providing thereon a sample signal corresponding to at least the first and second interfering signals and a desired signal received by the receiver antenna; a synchronous detector, the synchronous detector having at least two inputs respectively electrically coupled to the first and second directional couplers and being responsive to the second output signal of the first coupler and the sample signal of the second coupler, the synchronous detector comparing the first coupler second output signal and the sample signal and providing at least one detector output signal in response thereto; a signal controller, the signal controller having a first input electrically coupled to the first directional coupler and being responsive to the first output signal of the first coupler, and at least a second input electrically coupled to the synchronous detector, the signal controller having an output and providing thereon a cancellation signal in response to the detector output signal; and a subtractor, the subtractor being electrically coupled to the receiver transmission line and being further electrically coupled to the signal controller, the subtractor having an input on which is provided the cancellation signal, the subtractor effectively injecting the cancellation signal onto the receiver transmission line carrying the received interfering and desired signals, the cancellation signal injected into the receiver transmission line being equal in amplitude and opposite in phase to at least one of the first and second interfering signals received by the receiver antenna and carried by the receiver transmission line so as to cancel at least the one interfering signal on the receiver line; the auxiliary antenna having a non-zero phase relationship for the first and second interfering signals relative to the receiver antenna and thereby introducing a phase difference between the first and second signals relative to the receiver antenna; the auxiliary antenna being spaced apart from the receiver antenna a predetermined distance such that the first and second interfering signals are received by the auxiliary antenna and the receiver antenna with a phase difference which is equal and opposite to that which is introduced by the auxiliary antenna, whereby the first and second signals are received in the same phase in the interference cancellation system relative to the receiver antenna.
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2. A method for cancelling at least two interfering signals in a radio receiver system to which an interference cancellation system is connected, the radio receiver system having a receiver antenna, a receiver and a receiver transmission line electrically coupling the receiver antenna to the receiver, the interference cancellation system including an auxiliary antenna having a non-zero phase relationship for the two interfering signals relative to the receiver antenna and thereby introducing a phase difference between the two interfering signals relative to the receiver antenna, the method comprising the step of:
positioning the auxiliary antenna of the interference cancellation system and the receiver antenna of the radio receiver system in a spaced apart relationship by a predetermined distance so that the two interfering signals are received by the auxiliary antenna and the receiver antenna with a phase difference which is equal and opposite to that which is introduced by the auxiliary antenna, whereby the two interfering signals are received in the interference cancellation system in the same phase relative to the receiver antenna.
Specification
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Current AssigneeAmerican Nucleonics Corp. (Eaton Corporation PLC.)
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Original AssigneeAmerican Nucleonics Corp. (Eaton Corporation PLC.)
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InventorsTalwar, Ashok K.
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Primary Examiner(s)Kuntz, Curtis
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Assistant Examiner(s)Belzer, Christine K.
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Application NumberUS07/483,900Time in Patent Office852 DaysField of Search455/278, 455/272, 455/136, 455/273, 343/713, 343/841, 343/853US Class Current455/278.1CPC Class CodesH01Q 3/2629 Combination of a main anten...H04B 1/126 having multiple inputs, e.g...
