Hi One other possibility:
The GPS does a fast survey to get going. Then it starts a long / precision survey. It only stores the result if it finishes the precision survey. A good survey might be 10, 24, 48 or 72 hours…. Sure would be nice to have some basic info on these beasts …. Bob > On Oct 31, 2014, at 7:35 PM, Hal Murray <hmur...@megapathdsl.net> wrote: > > > b...@evoria.net said: >> I've noticed the same. In looking at the Satstat program, it appears that >> when you enter a location, that's only treated as a hint. There is also a >> value you can set to zero that supposedly tells it to come up with the last >> hold value. It didn't seem to work for me. I've finally got my location >> and power cords in more or less permanent locations, but things happen. >> And, I won't be getting a UPS for it for quite some time. Maybe someone >> else has the secret sauce. > > There are several ideas tangled up in this area. > > If the GPS receiver has a recent enough almanac and you tell it the time > and/or location, it can get started much quicker. The satellites broadcast > on a known frequency, but the Doppler pushes that a long distance relative to > the bandwidth. The almanac and time+location lets it compute which > satellites are visible and the frequencies to listen on. That shortens a > long search. > > Most/many GPS receivers have a watch crystal and clock and battery (or > supercap) for this purpose. > > GPSDOs are usually used at fixed locations. If it saves the surveyed > location it can avoid another survey on power up. You can save the surveyed > location in flash so a battery isn't required. > > Some GPSDOs automatically save the results of a survey. Some don't. The > Z3801A does an automatic save. The TBolt requires a command to save it. > > It can also save the GPS-UTC offset so it can deliver correct time in UTC > without waiting to get that info from a satellite. > > > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > 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. _______________________________________________ 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.