Hello everyone, On Mar 16 Feb 2010, ce-test, qualified testing bv - Gert Gremmen wrote: > No it ain't correct. > Satellite signals are blocked by conductive materials > such as metals, and to a limited extend by materials > containing humidity (= limited conductivity) such as leaves > and possibly concrete. > Due to their high frequency GPS signal tend to behave like light, > meaning that when there is metal in the line of sight between > GPS and satellite, there is decreased reception quality. > Most satellites can be seen (in west Europe and USA) in the southern > direction, and an uncovered horizon will give better signals.
Exactly. I just want to add, that as well meshes of conductive material with a mesh distance narrower than about 19 cm will tend to block GPS signals (most but not all steel armed concrete). 19 cm = lambda = c/f = 3*10^8/1575.42 m/s/Mhz It seems there are certain GPS chips (SiRFstar-III) that use additionally other GPS channels/ protocols and are capable to compensate signal loss of the main GPS channel. Cheers, Jochen _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk