Dual clock power conservation system and method for timing synchronous

Abstract

A system is provided to time the periods of known inactivity in a synchronous communications system in such a manner as to allow the high speed oscillator, used in the various timing, modulation, and demodulation operations of a portable communications unit, to be shut off without a significant loss in timing resolution. A low power, low speed, oscillator is used to measure a majority of the inactive period to save battery power. The low speed oscillator has a frequency too slow to provide the resolution necessary for accurate timing. However, a small portion of the inactive period is timed with the high frequency oscillator. The fine resolution of the time segment measured by the high speed oscillator, when combined with segment of time measured by the low speed oscillator, yields a measurement of the inactive period that is approximately the same as obtained when just the high speed oscillator is used. A method of turning off a high speed oscillator in the timing of an inactive period between communications in a synchronous communications system is also provided for the purpose of conserving battery power.