Semtech Corporation
ULTRALOW POWER GNSS RECEIVER

Abstract:

A system for updating almanac data in low-power GNSS mobile devices (30-34), including a server that keeps a local copy of the almanacs stored in each of the devices and evaluates repeatedly the quality of the almanac of each of the mobile devices (30-34). The evaluation comprises predicting the Doppler shifts for all the satellites potentially receivable by the mobile device using the orbital parameters in the copy and comparing the result with an accurate determination of the same Doppler shifts based on real orbital data.