Abstract: A circuit is disclosed for switching power to a battery operated device, particularly a portable radio transceiver. The power control circuit uses an on/off switch that remains in a fixed "on" or "off" position instead of using a momentary push button switch. The circuit allows powering down the radio to prevent deep discharging of the battery even though the switch remains in the "on" position. Also, the circuit allows the radio to continue to be powered up under microprocessor control after the switch is placed in the "off" position.

Abstract: In a radio employing continuous tone or digital coded squelch system, fast settling tone processing circuitry is disclosed for a tone processing path which includes an FM detector, low pass filters and a tone limiter. In an exemplary embodiment, a capacitor at the output of the FM detector in the tone/data processing path is charged as rapidly as possible to a new DC level, for example, by an off frequency transmitter. A pulse is generated by, for example, the transceiver microprocessor which initiates the rapid charging of the capacitor as soon as it is detected that data needs to be read from the tone/digital data processing circuitry for decoding. Such a pulse is generated by the microprocessor whenever channel frequencies are changed and/or the carrier activity sensor becomes active.