Apparatus and method for prolonging battery life in a portable telephone

Abstract

A cordless telephone arranged for operation in a frequency hopping system provides for conserving battery power in a portable unit when this unit is located remote from its charging station and in a standby state. While in the standby state, the portable unit resides in a low power monitoring mode which includes deactivating certain internal circuitry and periodically activating and deactivating other selected internal circuitry for conserving battery power. When the portable unit is periodically activated from a deactivated state, battery power is conserved through an adaptive operation that reduces considerably the length of time that the selected internal circuitry needs to remain turned on. This reduced on-time period for the selected internal circuitry is provided as long as the base unit is detected as frequency hopping with at least one other of the portable units in the system. If the base unit is not detected as frequency hopping, however, the length of time that the selected internal circuitry remains on is left at its normal, unreduced on-time period. Energy savings for a portable unit operating with the reduced on-time period are significantly greater than those realized when the portable unit is operated with the normal, unreduced on-time period. Another portable unit operating as the base unit may also provide a frequency hopping signal suitable for use by the adaptive operation in providing the reduced on-time period for the internal circuitry of the portable unit.