Interference detection technique
First Claim
1. A circuit for detecting and indicating interference of a received signal having a high frequency angular modulated component and a low frequency amplitude modulated fading component having a fading frequency, the circuit comprising:
- a logarithmic amplifier having an input for receiving the received signal and an output for providing a logarithmic amplifier output;
means, coupled to the logarithmic amplifier, for sampling the logarithmic amplifier'"'"'s output at a sampling rate based on the high frequency angular modulated component within a sampling window having a duration less than the period associated with the fading frequency of the low frequency amplitude modulated fading component; and
means, in communication with said sampling means, for detecting and indicating interference of the received signal as a function of amplitude modulations detected at the logarithmic amplifier output.
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Abstract
Briefly described, the present invention is a circuit for detecting and indicating a level of interference on a high frequency angular modulated signal. This circuit includes a logarithmic amplifier for receiving high frequency angular modulated signals and for providing a logarithmic amplifier output in response thereto. Next, the angular modulated signals are detected to determine a level of associated FM modulation thereof. Finally, a processor, programmed to distinguish those high frequency spectrum components due to interference from those due to other sources, determines a carrier to interference ratio. Of note, when the level of FM modulation at the logarithmic amplifier input exceeds a predetermined threshold, however, the associated carrier to interference ratio is ignored.
32 Citations
18 Claims
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1. A circuit for detecting and indicating interference of a received signal having a high frequency angular modulated component and a low frequency amplitude modulated fading component having a fading frequency, the circuit comprising:
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a logarithmic amplifier having an input for receiving the received signal and an output for providing a logarithmic amplifier output; means, coupled to the logarithmic amplifier, for sampling the logarithmic amplifier'"'"'s output at a sampling rate based on the high frequency angular modulated component within a sampling window having a duration less than the period associated with the fading frequency of the low frequency amplitude modulated fading component; and means, in communication with said sampling means, for detecting and indicating interference of the received signal as a function of amplitude modulations detected at the logarithmic amplifier output. - View Dependent Claims (2, 3, 4, 5)
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6. A circuit for detecting and indicating radio interference of a signal having a high frequency angular modulated component and a fading component having a fading frequency, the circuit comprising:
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a logarithmic amplifier having an input for receiving the signal and an output for providing a logarithmic amplifier output; an FM detector, coupled to the logarithmic amplifier input, for receiving the signal, detecting an associated FM modulation thereof, and providing an output in response thereto; an analog-to-digital converter, coupled to the logarithmic amplifier and the FM detector, for sampling their outputs at a sampling rate based on the high frequency angular modulated component within a sampling window having a duration less than the period associated with the fading frequency to provide digital samples thereof; and a processor in communication with the analog-to-digital converter, for detecting and indicating interference of the signal as a function of amplitude modulations detected at the logarithmic amplifier output. - View Dependent Claims (7, 8, 9)
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10. A circuit for detecting and indicating radio interference of a signal having a high frequency angular modulated component and a fading component having a fading frequency, the circuit comprising:
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a logarithmic amplifier having an input for receiving the signal and an output for providing a logarithmic amplifier output; an FM detector, coupled to the logarithmic amplifier input, for receiving the signal, detecting an associated FM modulation thereof, and providing an output in response thereto; an analog-to-digital converter, coupled to the logarithmic amplifier and the FM detector, for sampling their outputs at a sampling rate based on the high frequency angular modulated component within a sampling window having a duration less than the period associated with the fading frequency to provide digital samples thereof; a processor in communication with the analog-to-digital converter, for detecting and indicating interference of the signal as a function of amplitude modulations detected at the logarithmic amplifier output, determining an angular modulated signal to interference ratio, and aborting the angular modulated signal to interference ratio'"'"'s determination when the FM detector output exceeds a predetermined threshold.
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11. A communication device comprising:
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a receiver circuit for receiving a signal having a high frequency angular modulated component and a fading component having a fading frequency; an interference detection circuit, coupled to the receiver circuit, for detecting and indicating radio interference of the received signal comprising; a logarithmic amplifier having an input responsive to the receiver circuit for receiving the signal and an output for providing a logarithmic amplifier output; a sampling device, responsive to the logarithmic amplifier, for sampling the logarithmic amplifier'"'"'s output at a sampling rate based on the high frequency angular modulated component within a sampling window having a duration less than the period associated with the fading frequency to provide digital samples thereof, and means, in communication with the sampling device, for detecting and indicating radio interference on the signal as a function of amplitude modulations detected at the logarithmic amplifier output; and means, in communication with the interference detection circuit, for reducing the radio interference. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A communication device comprising:
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a receiver circuit for receiving a signal having a high frequency angular modulated component and a fading component having a fading frequency; an interference detection circuit, coupled to the receiver circuit, for detecting and indicating radio interference of the received signal comprising; a logarithmic amplifier having an input responsive to the receiver circuit for receiving the signal and an output for providing a logarithmic amplifier output; a sampling device, responsive to the logarithmic amplifier, for sampling the logarithmic amplifier output for a period less than the period associated with the fading frequency to provide digital samples thereof; means, in communication with the sampling device, for detecting and indicating radio interference in the signal as a function of amplitude modulations detected at the logarithmic amplifier output; means, in communication with the interference detection circuit, for reducing the radio interference; an FM detector coupled to the logarithmic amplifier input, for receiving the signal, detecting an associated FM modulation of the signal, and providing an output in response to the associated FM modulation of the signal; and a processor comparing the FM detector output to a predetermined threshold and inhibiting the means for reducing the radio interference when the FM detector output exceeds the predetermined threshold.
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18. A base site for use in a wireless communication system comprising:
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an antenna receiving a signal having a high frequency angular modulated component and a fading component having a fading frequency; and a circuit for detecting and indicating radio interference of the signal, the circuit comprising; a logarithmic amplifier having an input for receiving the signal and an output for providing a logarithmic amplifier output; an FM detector, coupled to the logarithmic amplifier input, for receiving the signal, detecting an associated FM modulation thereof, and providing an output in response thereto; an analog-to-digital converter, coupled to the logarithmic amplifier and the FM detector, for sampling their outputs at a sampling rate based on the high frequency angular modulated component within a sampling window having a duration less than the period associated with the fading frequency to provide digital samples thereof; and a processor in communication with the analog-to-digital converter, for detecting and indicating interference of the signal as a function of amplitude modulations detected at the logarithmic amplifier output.
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Specification