GPS Signals
Fleeting- External reference: https://en.wikipedia.org/wiki/GPS_signals
GPS signals - Wikipedia
almanac consists of coarse orbit and status information for each satellite in the constellation, an ionospheric model, and information to relate GPS derived time to Coordinated Universal Time (UTC). Each frame contains a part of the almanac
almanac is transmitted by each satellite in 25 frames total (requiring 12.5 minutes).[17]
almanac serves several purposes. The first is to assist in the acquisition of satellites at power-up by allowing the receiver to generate a list of visible satellites based on stored position and time, while an ephemeris from each satellite is needed to compute position fixes using that satellite
Advances in hardware have made the acquisition process much faster, so not having an almanac is no longer an issue
second purpose is for relating time derived from the GPS (called GPS time) to the international time standard of UTC.