Abstract: A subscriber unit of a time division multiple access (TDMA) radiotelephone system is, from a power consumption standpoint, reconfigured in each time slot of a TDMA frame to a power consumption tessellation in which subscriber unit circuit components not needed for communication signal processing in that time slot are powered down, and other components are powered up. Some circuit components are powered down by switching their power supply circuits. In order to minimize the extent of circuitry that must be provided to distribute power consumption control signals, other techniques (which utilize circuitry provided for other purposes), such as clock frequency control or power down commands, also are utilized to modify controlled circuit component power consumption without actually controlling power supply circuits.

Abstract: A battery heater uses the internal resistance of the battery as the battery heating element. In one embodiment, a DC battery charger and a programmable battery load, is used in a closed loop temperature control system. In another embodiment, a DC battery charger and a resistor or small auxiliary battery heater, is used in a closed loop temperature control system. The programmable load or the small auxiliary battery heater, is enabled during full charge, low temperature conditions. The resistor or small auxiliary heater serves to both heat the battery and draw down the battery charge. In yet another embodiment, an AC heater power supply and a DC battery charger, is coupled to the battery in a closed loop temperature control system.