Distortion reducing circuit in FM receiver
AssigneeSanyo Electric Co., Ltd.
InventorsTakenori Ugari, Yoichi Yano
Life of this patent
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Abstract
A distortion reducing circuit in an FM receiver comprises a distortion detector for receiving the output of an FM demodulating circuit. The distortion detector comprises a high pass filter, the output of which is applied to a capacitor so that the same is rapidly charged. The conduction of the transistor is changed as a function of the charge voltage across the capacitor and a high frequency component in the output of the FM demodulating circuit is reduced in association with the conduction of the transistor.
Claims21
A distortion reducing circuit in an FM receiver, said FM receiver comprising:
- front end means for receiving an FM signal containing information corresponding to a range of frequencies and providing an intermediate frequency output signal;
- circuit means for receiving and deomodulating said intermediate frequency output signal to produce a demodulating signal which includes a component corresponding to distortion in the FM signal received by said front end means;
- utilization means responsive to said demodulated signal for reproducing information contained in said FM signal;
- means responsive to the demodulated output signal of said demodulating circuit means for detecting said distortion component;
- and
- distortion reducing means responsive to said detected distortion component of said distortion detecting means for reducing a high frequency component of the range of frequencies included in said demodulated output signal which is applied to said utilization means while permitting relatively unaffected passage of a low frequency component of a range of frequencies included in said demodulated output signal to said utilization means,
- said distortion reducing means being rapidly responsive to cause reduction upon the received FM signal going from a state of no distortion to one with distortion and less rapidly responsive upon the FM signal going from a state with distortion to one without distortion.
A distortion reducing circuit in an FM receiver said FM receiver comprising:
- front end means for receiving an FM signal containing information corresponding to a range of frequencies and providing an intermediate frequency output signal;
- circuit means for receiving and demodulating said intermediate frequency output signal to produce a demodulated signal which includes a component corresponding to distortion in the FM signal received by said front end means;
- utilization means responsive to said demodulated signal for reproducing information contained in said FM signal;
- means responsive to the demodulated output signal of said demodulating circuit means for detecting said distortion component;
- distortion reducing means responsive to said detected distortion component of said distortion detecting means for reducing a high frequency component of the range of frequencies included in said demodulated output signal which is supplied to said utilization means while permitting low frequency component of relatively unaffected passage of a range of frequencies included in said demodulated output signal to said utilization means;
- charging/discharging circuit means;
- charging path means responsive to the output of said distortion detective means for supplying a charging current to said charging/discharging circuit means said high frequency reducing means being operable as a function of the charging voltage of said charging/discharging circuit means;
- discharging path means for discharging an electric charge in said charging/discharging circuit means;
- and
- a discharging time constant of said discharging path means being selected to be larger than a charging time constant of said charging path means.
Dependencies are inferred from the claim text.