Patent ID: 8588707

Claim:
A method, comprising: operating a multi-modal wireless device comprising wireless subsystems using a reference frequency at a first value for a first extended period of time corresponding to a time operating the wireless device within a first wireless service zone; shifting the reference frequency from the first value to a second value to compensate for one of a Doppler shift, a temperature drift, component aging, and other frequency mismatches, in its cellular subsystem, the shifting characterized at least in part by a controlled transition of the reference frequency at a predetermined time-rate-of-change, wherein the shifting of the reference frequency from the first value to the second value is performed responsive to a transition of the wireless device from the first wireless service zone to a second wireless service zone; and operating the wireless device using the reference frequency at the second value for a second extended period of time corresponding to a time operating the wireless device within the second wireless service zone; wherein the predetermined time-rate-of-change is adjusted based on the total operating tolerances from the wireless subsystems within the wireless device to allow for the wireless subsystems to operate interruption-free during the reference frequency shifting.