SYSTEM AND METHOD FOR FREQUENCY MANAGEMENT IN A COMMUNICATIONS POSITIONING DEVICE

摘要

A frequency management scheme for a hybrid communications/positioning device, such as a cellular/GPS or other combined device, generates a local clock signal for the communications portion of the device, using a crystal oscillator or other part. The oscillator output may be corrected by way of an automatic frequency control (AFC) circuit or software, to drive the frequency of that clock signal to a high accuracy. The base oscillator may be delivered to a phase locked loop to drive a high-frequency clock for the cellular or other communications portion of the hybrid device, which clock signal may also be frequency-converted to drive a GPS or other positioning receiver. The extraction of a base GPS clock from the radio frequency reference eliminates the need for a second oscillator or synthesizer for that portion of the hybrid device. In embodiments, AFC tuning on the cellular clock may be omitted and the high frequency clock signal divided down for delivery to the GPS or other positioning receiver may be adjusted via a frequency prescaler, or other module.