| 摘要 |
PURPOSE:To miniaturize a portable radio equipment by providing an AGC circuit inputting an output of the portable radio equipment and a reference voltage generating circuit to an on-vehicle fixed radio equipment and controlling a power amplifier through the comparison between an AGC control voltage and a reference voltage. CONSTITUTION:In order to control a transmission output 6A of an on-vihicle fixed section 2A, an output voltage 14A from an output control circuit 12 is reduced by a control signal 11A from a control section 7 of a portable radio equipment 1A at first, the gain of a power amplifier circuit 13 is reduced to control the transmission output 3A. Thus, the input level of the AGC circuit 15 of the fixed section 2A is lowered and the gain is increased, then a control voltage 18 is increased more than a reference voltage 19 from a reference voltage generator 16. This is detected by a voltage comparator circuit 17, the comparison signal 20 is transmitted to an output control circuit 9A, the supply voltage 10A to the on-vihicle power amplifier 5 is lowered to reduce the gain of the circuit 5 thereby controlling the transmissin output 6A. Even when the output 3A from the radio equipment 1A is fluctuated, the input level of the circut 5 is kept constant. Since no transmission output controller mounted on a vehicle is required to the radio equipment 1A, the circuit is miniaturized. |
