Abstract: A radio receiver in which, even with large variability in the components, the receiving conditions can be set according to the antenna input level in a uniform way. A high frequency cutoff circuit 30 reduces high frequency components in a composite signal by a high frequency cutoff ratio depending on a voltage applied to an HCC pin 30a. A principal signal included in the composite signal is demodulated by a principal signal demodulator 32, and a subsidiary signal is demodulated by a subsidiary signal demodulator 34. In the subsidiary signal demodulator 34, based on a voltage applied to a SPC pin 34a, the subsidiary signal demodulation level is varied from 0 to 100% according to stereo separation characteristics, to control the stereo separation. A matrix circuit 36 regenerates left and right channel signals from the demodulated principal signal and subsidiary signal. A microprocessor 20 inputs a signal meter output voltage from an FM detector IC 12.

Abstract: An on-vehicle sound instrument with a face plate which does not require any switch mounted thereon to improve portability is not started unless the face plate is mounted on an instrument body, and even if any switch in the instrument body is manipulated. The face plate (30) detachably mounted on the instrument body (10) does not have any switch mounted thereon and includes operation keys (320). The instrument body (10) includes a microcomputer (40) for controlling sound signal outputs and adjustments and an input unit (44) formed of switches for inputting various data to the microcomputer (40) through inputs from the operation keys (320). When the face plate (30) is removed from the instrument body (10) and, for example, a power switch is turned on, a start setting device (60) prevents the microcomputer (40) from activating. The start setting device (60) includes two switches (62, 64) which are simultaneously turned on when the face plate (30) is dismounted from the instrument body (10).

Abstract: A frequency synthesizer includes a phase detector for comparing a reference frequency with a feedback frequency, a filter connected to the phase detector for permitting the passage of low frequency therethrough, a voltage controlled oscillator connected to the filter, a multistage frequency converter for receiving the oscillator signal from the voltage controlled oscillator as an input, and a divider for dividing the output of the multistage frequency converter to form the feedback frequency. The multistage frequency converter includes a plurality of frequency converters connected in series or parallel to each other, each of the frequency converters being adapted to perform a non-integer division. The division ratio can be set arbitrarily and finely. Thus, the feedback frequency inputted to the phase detector can be maintained constant and yet higher, irrespectively of the output frequency of the frequency synthesizer.

Abstract: In a tuner for converting antenna input signal into audio signals, tuner circuit components are mounted on a tuner circuit substrate. Of the tuner circuit components, FM wave front end circuit components constituting a high-frequency amplifying circuit, a mixing circuit and a local oscillating circuit are surrounded by a shield case. An antenna jack including an earth tube and a signal terminal insulated from the earth tube is mounted on the tuner circuit substrate. The signal terminal of the antenna jack is connected to an antenna input signal pattern of the tuner circuit substrate. The earth tube of the antenna jack is forced in and supported by a jack attachment plate that is an extension of the shield case.

Abstract: An electronic volume control system has an UP key (1) for increasing the level of volume, a DOWN key (2) for decreasing the level of volume and a control (3) for controlling to increase or decrease the level of volume at the primary rate of volume change, based on the operation of each of the keys (1 and 2). The control (3) can set a fine adjustment mode in which the level of volume can be increased or decreased at a secondary rate of volume change which is smaller than the primary rate of volume change. The control (3) sets the fine adjustment mode when the time interval from a time point when one of the keys (1 or 2) is turned off to another time point when one of the keys (1 or 2) is subsequently turned on is within a preset time period. In order to enable the setting of the fine adjustment mode, a preset time period is set in UP-key or DOWN-key counter (10 or 11), if required. This preset time period is counted down for each unit time.