Fast position fix under reception poor area

Overview
AGPS enabled GPS module can start-up faster, perform faster TTFF (time to first fix), and obtain faster positioning information under weak signal environments.
On average, using AGPS cuts the GPS module "cold-start" time by half, and "warm-start" down to one second.

Background
When GPS receiver is powered on for the first time, almanac and ephemeris data from the satellites must be transmitted continuously for 40 seconds without interruption to the GPS receiver for normal operation.

However, the transfer time may be significantly longer, or worse, unable to start-up, if the GPS receiver is in a very weak signal environment such as urban canyon, forest with dense foliage, or places where the GPS receiver cannot get a clear view of the sky and the data transmission is constantly interrupted.

The interrupted data transmission not only will drain precious power supply in the case of mobile application, but more significantly, valuable time will be wasted as frustration build-up while waiting for GPS receiver to start-up.

Solution
By uploading pre-calculated almanac and ephemeris data in proprietary "EPO (Extended Prediction Orbit)" data format to the GPS module, the waiting time for the initial data transmission from the satellites is now significantly shortened. The EPO data contains predicted ephemeris data for 14 days and need to be re-downloaded once it expires.