Clarion Co

Satoru Tazaki

Yasuhiro Yoshioka

Kiyoshi Amazawa

Takao Miyazaki

An FM multipath noise reduction circuit is disclosed, in which a condenser for rapid charging is connected between the power source line and a charge/discharge condenser disposed in a level shift circuit system so that the rise time constant of the control output voltage at the power source switch-on, the AM/FM mode switch over, etc. is equal to that after the power source switch-on.

FM multipath noise reduction circuit

A control circuit in an FM radio receiver includes a current mirror circuit which extracts a ripple component caused by a multipath disturbance and superposed on an S-meter output voltage from an intermediate frequency amplifier/detector of the FM radio receiver, and decreases the S-meter output voltage in response to the degree of the ripple component to use the decreased S-meter output voltage as a control voltage for control of separation and high-cut operations of a stereo demodulating stage of the FM radio receiver.

Circuit for controlling separation and high-cut operation of a stereo

A high-cut and high-blend control voltage generating circuit for activating a noise reduction circuit of an FM stereo receiver is configured to be simply responsive to multipath noises and never to plug noises. A changing and discharging circuit in the control voltage circuit may have a relatively long charging time constant, and the voltage control circuit may be configured to be simply responsive to multipath noises above a predetermined level. Thus the circuit is much less liable to operate erroneously.

Control voltage generating circuit for activating a noise reduction

An AC-DC transformation circuit according to this invention facilitates operational stability by transforming an AC inputted voltage first into current and then transforming the current into a DC voltage.

AC-DC transformation circuit

An automatic tuner control system characterized in that the device comprises a detector for detecting a signal level in a radio receiver, a means for setting a reference signal level and a comparator means for doing comparison between the signal level and the reference signal level. Thus, the device is arranged to switch the received waves of the radio receiver in response to the result of the comparison in the comparator means and various conditions.

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Tokyo, Japan

Satoru Tazaki