On 26 September 2014 13:52, Azelio Boriani <azelio.bori...@gmail.com> wrote: > From gpsinformation.net: > > In the frequency allocation filing the L1 C/A power is listed as 25.6 > Watts. The Antenna gain is listed at 13 dBi. Thus, based on the > frequency allocation filing, the power would be about 500 Watts (27 > dBW). > > Now, the free space path loss from 21000 km is about 182 dB. Take the > 500 Watts (27 dBW) and subtract the free space path loss (27 - 182) > and you get -155 dBW. The end of life spec is -160 dBW, which leaves > a 5 dB margin.
I have not checked your figures, but assuming they are right, the -155 dBW would be based on a receiver antenna with 0 dBi gain, since that is what the free space path loss assumes. Any lossless antenna will have a peak gain of > 0 dBi. > And if you really get into it, you'll discover ALL of the following > represent the same approximate signal strength for GPS on the face of > the earth (m stands for milliwatts and m2 stands for meters squared): > > -160 dBW, -130 dBm, -135 dBW/m2, -105 dBm/m2, -223 dBW/Hz, -163 > dBW/MHz, -193 dBm/Hz, -198 dBW/m2/Hz, -138 dBW/m2/MHz As I say, without stating the properties of the receiving antenna, absolute power levels are not a sensible unit. Dave _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
