A method and a device for controlling a radio transmitter. In the method, the radio transmitter is alternately caused to assume an ON state in which a desired outbound RF power is transmitted, and an OFF state in which no RF power is transmitted, the RF power being determined in the ON state by using a power control signal (V.sub.c) controlling the amplification of transmitter amplifiers (3, 4). For ensuring that the data period falls within the useful period of the transmitter, within which the value of the RF power to be transmitted is constant, a data stream (D2) is delayed with respect to the power control (V.sub.c) when the transmitter is caused to assume the ON state.
A multi-carrier radio transmission apparatus provided with an idling detection means for detecting when all of a plurality of modulators are idling and a selective automatic level control means for selectively driving only specific modulators among a plurality of modulators so as to cause them send out their modulated outputs when receiving an idling detection signal from the idling detection means and for enabling an automatic level control unit to perform an automatic level control operation only when receiving an idling detection signal, whereby it is possible to realize a power detector which can exhibit an effect equivalent to that of a diode with a wide dynamic range even when use is made of a diode with a narrow dynamic range.
When transmission power control bit data is transmitted from a base station, a transmission power control circuit controls the transmission power of a transmitting amplifier and the transmission power on-off ratio according to the transmission power control bit. That is, the mean transmission power is determined according to the transmission power control bit data. At this time, the transmission "on" time ratio is reduced as much as possible according to: (mean transmission power)=(transmission power when transmission is "on").times.(transmission "on" time ratio), and (transmission power when transmission is "on") (transmission power when transmission is "on") (maximum transmission power of transmitting amplifier).
An electrical power management system for supplying power to a computer peripheral having a relatively high intermittent power demand, such as a packet-switched data radio. A first self-contained rechargeable power supply, outputting power appropriate for the electrical appliance, stores electrical energy and supplies power to the appliance. A second self-contained rechargeable power supply stores electrical energy and supplies electrical power to intermittently recharge the first power supply. The first and the second power supplies can be such self-contained units as single or multicell batteries or capacitors. Preferably, the first power supply is a battery or a capacitor and the second power source is an internal power supply of a portable personal computer.
