Abstract: The invention concerns a method (200) and system (100) for selective control of charging a power source (122). The method can include the steps of charging (212) the power source of an electronic device (136) in which the electronic device also includes a global positioning system unit (118) and conducting (216) a session for the global positioning system unit. The method can also include the step of—in response to the session—selectively throttling (218) the flow of current to the power source of the electronic device to reduce the effect of thermal variation on the operation of the global positioning system unit.

Abstract: 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 delivered to a phase locked loop to drive a high-frequency clock for the cellular or other communications portion of the hybrid device. A processor may determine frequency error between the phase locked loop and base station or other reference, to derive a digital frequency tracking message. A Doppler search or other logical control message may likewise be communicated from the processor to a GPS or other positioning receiver. The GPS receiver circuitry may consequently adjust Doppler center, window width or other parameters to enhance time to first fix or other performance.

Abstract: 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.

Abstract: 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 delivered to a phase locked loop to drive a high-frequency clock for the cellular or other communications portion of the hybrid device. A processor may determine frequency error between the phase locked loop and base station or other reference, to derive a digital frequency tracking message. A Doppler search or other logical control message may likewise be communicated from the processor to a GPS or other positioning receiver. The GPS receiver circuitry may consequently adjust Doppler center, window width or other parameters to enhance time to first fix or other performance.