METHODS, SYSTEMS, WIRELESS TERMINALS, AND COMPUTER PROGRAM PRODUCTS FOR CALIBRATING AN ELECTRONIC CLOCK USING A BASE REFERENCE SIGNAL AND A NON-CONTINUOUS CALIBRATION REFERENCE SIGNAL HAVING GREATER ACCURACY THAN THE BASE REFERENCE SIGNAL

摘要

Electronic clock calibration systems, methods, and computer program products use a calibration reference signal to calibrate an electronic clock that generates an output signal and that is responsive to a base reference signal. The base reference signal is less accurate than the calibration reference signal and, therefore, has an actual frequency and an ideal frequency associated therewith. The difference between the actual frequency and the ideal frequency represents the inaccuracy of the base reference signal. The calibration reference signal may be used to determine this difference between the actual frequency and ideal frequency of the base reference signal. Once this difference is determined, the frequency of the electronic clock output signal may be adjusted to compensate for the inaccuracy of the base reference signal. The base reference signal is often generated by a crystal oscillator circuit in consumer electronic devices, which is susceptible to frequency drift based on age, temperature, shock, and other environmental factors. Crystal oscillator circuits have an advantage in that they use relatively little power and, thus, tend to preserve battery life. The accuracy of a crystal oscillator circuit may be improved through use of a more accurate calibration reference signal that need not be available continuously.