GPS PROS Group Forum is for any member of LSU that is a professional land surveyor using primarily GPS in the field. Geodetic / Global Positioning Systems (GPS) Get help and offer support with survey grade GPS!
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GPS - is the USA Constelation of 30 satellites. They are all 100% operational and they have 6 orbital planes. International access.
GLONASS - is the Russian constelation of satellites. They are 60% operational and they have 3 orbital planes. International access.
Galileo - is the growing European constelation. They launched 2 test satellites on Aug. 6, 2008
Compass/Bei Douz - is the growing Chinese constelation. They launched 5 satellites on Aug. 6, 2008
GNSS is the umbrella that tracks and manages all the constelations of satellites. You need multi channel and multi frequency to use GNSS. Modernazation has added to the common L1 1575.42 MHz and L2 1227.60 MHz frequency. New bands are L2c a more reliable measurement, easy to track, redundant signal to assist with interferances. L5 Improved signal structure, higher transmissit power, wider band width, faster signal acquisition. L1M & L2M Military and the L1c Civilian.
All are subject to the errors caused by the Ionoshere and the Troposhere. Known as Atmophere Error Factor.
Troposhere is the lowest level in our atmosphere. All weather occurs in this layer. Veriation in temperature, pressure and humidity can effect speed of radio frequency and impact in lower accuracy levels.
Ionoshere is 100 km = 328083.989 ' above the earths surface. It is charged with particalesthat can impact transmissions rate.