Hi The power at transmit is partially a function of making it tough for backyard "what ever nuts" to broadcast through the sats. Since there's no demodulation / decoding / encoding / remodulation, power is the only practical lockout mechanism.
It's secondarily a function of the massive amount of random RF we generate all over the planet. They want signals that are "clean" to -60 dbc or better. They actually sell slots that are in the > -50 dbc range to people for specialized use. There is some modulation magic involved, so that's not quite the same as main transmit is 60 db > sum of (everything else). http://en.wikipedia.org/wiki/Transponder_(satellite_communications) Bob On Jul 3, 2013, at 3:42 PM, Azelio Boriani <[email protected]> wrote: > Sure about the "bent pipe"? If so it seems that much power is required > at the transmitting ground station... > > On Wed, Jul 3, 2013 at 7:48 PM, Attila Kinali <[email protected]> wrote: >> On Wed, 3 Jul 2013 08:29:02 -0400 >> Bob Camp <[email protected]> wrote: >> >>> There are two batches of GPS / WAAS sats up there: >>> >>> 1) The ones with numbers above 100 that are geosync and that only do WAAS >>> >>> 2) The ones with numbers <= 32 that do nav. These are not geosync. >>> >>> I believe the only ones with corrected / high stab clocks on board are >>> those in the second group. The stuff in the first group aren't dedicated >>> sats, just leased transponders on conventional multipurpose geosync birds. >> >> I don't know about WAAS, but AFAIK the EGNOS signals are generated on >> ground using Cs references and retransmitted by the satelites using >> a "bend pipe". Ie. the signals should be of time-nut quality even without >> high accuracy frequency standards in the birds themselves. >> >> (Sorry, i'm not able to find where i read about that, so no references today) >> >> Attila Kinali >> >> -- >> The people on 4chan are like brilliant psychologists >> who also happen to be insane and gross. >> -- unknown >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
