Yes.. You put a gain antenna on the space craft, so for the same tx power, you get the same flux density on the ground. The gps height was chosen for a variety of reasons. It is out of the debris band, for one. There's also a tradeoffs on launch costs, etc. GPS world magazine had a great multipart article on the history and design last year
On Jul 31, 2013, at 5:25, Magnus Danielson <[email protected]> wrote: > The MEO/GEO distance difference isn't all that great, and comparable signal > strength is seen from the WAAS/EGNOS (SBAS in general) without too much > difficulty in design. > > Cheers, > Magnus > > On 30/07/13 16:51, bg wrote: >> Satnav are not LEO but MEO. Which is good - less sv to cover the earth. Less >> good because distance is higher compared to LEO regarding signal power at >> earth. >> >> -- >> >> Björn >> >> >> Skickat från min Mobil >> >> -------- Originalmeddelande -------- >> Från: Scott McGrath<[email protected]> >> Datum: 2013-07-30 14:50 (GMT+01:00) >> Till: [email protected],Discussion of precise time and frequency >> measurement<[email protected]> >> Kopia: Discussion of precise time and frequency >> measurement<[email protected]> >> Rubrik: Re: [time-nuts] Story in the Economist about GPS jamming >> >> Any competent engineer could have told the powers that be that a satellite >> system based in LEO has a relatively high risk profile from the >> Universe/hostile activity/spoofing and jamming >> >> Yes GPS is/was oversold. >> >> Trouble is Clarkes law applies here (any sufficiently advanced technology is >> indistinguishable from magic). And this applies double to the technological >> illiterates in DC >> >> See Sen 'Tubes' Stevens for the canonical example >> >> Sent from my iPhone >> >> On Jul 29, 2013, at 12:46 PM, "J. Forster"<[email protected]> wrote: >> >>> It seems to me that GPS has been oversold as the be all, end all system >>> that made all other systems obsolete and GPS has become all but an >>> indespensible utility. >>> >>> Reports like this, could well be used to promote a backup, like LORAN or >>> eLORAN, just as public buildings have backup generators. >>> >>> YMMV, >>> >>> -John >>> >>> ================== >>> >>> >>>> >>>> http://www.economist.com/news/international/21582288-satellite-positioning-data-are-vitalbut-signal-surprisingly-easy-disrupt-out?fsrc=scn/tw/te/pe/outofsight >>>> >>>> -Bill >>>> >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> 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. >> _______________________________________________ >> 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.
