GPS satellites transmit two radio signals. The signals are mark as L1 and L2. A Civilian GPS uses the L1 signal frequency (1575.42 MHz) in the UHF band. While the L2 frequency (1227.60 MHz) is used to measure the ionospheric delay by Precise Positioning Service (PPS) equipped receivers. All these signals travel by line of sight.
The GPS signal contains three different bits of information which are a pseudo random code, almanac data and ephemeris data.
Global Positioning System (GPS) 
Leave a comment