Adjacent channel interference suppressing system for FM receiver
AssigneePioneer Electronic Corporation
InventorEizi Ueno
Life of this patent
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Abstract
An adjacent channel interference suppressing system for an FM receiver which includes a first detecting device for amplifying and demodulating an intermediate frequency signal which has passed through a wide-band filter; a second detecting device for amplifying and demodulating an intermediate frequency signal which has passed through a narrow-band filter; a level adjusting device for receiving FM detection signals from the first and second detecting devices, and for complementarily and continuously adjusting the levels of the FM detection signals; and a control signal generating device for generating a control signal for controlling the level adjusting device according to the presence or absence of an adjacent channel interference.
Claims11
An adjacent channel interference suppressing system for an FM receiver, comprising:
- a wide-band filter for receiving an intermediate frequency signal;
- a narrow band filter for receiving the intermediate frequency signal;
- first detecting means for amplifying and demodulating the intermediate frequency signal which has passed through the wide-band filter;
- second detecting means including a narrow-band filter for amplifying and demodulating the intermediate frequency signal which has passed through the narrow-band filter;
- control signal generating means responsive to first outputs from said first and second detecting means for generating a control signal dependent upon the difference in the level of signals passed through said wide-band and narrow-band filters;
- and
- level adjusting means connected to receive second outputs from said first and second detecting means and responsive to said control signal from said control signal generating means for combining the second outputs from said first and second system means in a proportion dependent upon said control signal.
An adjacent channel interference suppressing system comprising:
- a wide-band filter for receiving an intermediate frequency signal;
- a narrow-band filter for receiving the intermediate frequency signal;
- first means, coupled to said wide-band filter, for amplifying and demodulating the output signal from said wide-band filter and for generating a first detection signal in accordance with a level of the output signal from said wide-band filter;
- second means, coupled to said narrow-band filter, for amplifying and demodulating the output signal from said narrow-band filter and for generating a second detection signal in accordance with a level of the output signal from said narrow-band filter;
- a differential amplifier for receiving the first and second generated detection signals and for generating a control signal in accordance with a difference between the first and second detection signals;
- level adjusting means for receiving the outputs of said first and second means, and responsive to said control signal for combining said outputs from said first and second detecting means in a proportion dependent upon said control signal.
A method of suppressing an adjacent channel interference, comprising the steps of:
- splitting an intermediate frequency signal into first and second intermediate frequency singals;
- filtering the first and second intermediate frequency signals at wide and narrow bands, respectively;
- amplyfing and demodulating each of the filtered first and second intermediate frequency signals;
- detecting and comparing the levels of the amplified and demodulated first and second intermediate frequency signals to generate a control signal in accordance with the difference in level;
- and
- mixing the amplified and demodulated first and second intermediate frequency signals in response to the control signal to generate a composite signal having a mixing ratio dependent upon the control signal.
Dependencies are inferred from the claim text.