Hi The more interesting event is when you re-flash a +/- 1 us navigation receiver and it instantly becomes a < +/- 100 ns timing receiver *without* position hold engaged.
Bob On Dec 29, 2012, at 10:20 PM, Said Jackson <[email protected]> wrote: > Bob, > > Our Position-Hold enabled units (Fury, Mini-JLT, various CSAC units, and > GPS-405 support accurate position reporting in ECEF, NMEA, and various other > standards. > > Users can select how many fixes are averaged for the position report. > > They can also be instantly switched back and forth between position hold, and > mobile mode using simple English SCPI commands. Some of them have built in 3 > axis accelerometers that allow instant detection of when the vehicle starts > moving so it can be switched into mobile mode at that time. > > We recently did a test by putting an antenna in a side window in the office > that had maybe 10% view of the sky, then let the unit run in mobile mode > while doing the auto survey. After two days, we switched it into position > hold mode. Most of the time it sees only one sat direct, all others are only > seen through multipath. The results are astonishing, SD went down from about > 30ns+ to about 8ns. Spikes to +/-150ns went away completely. > > I can post some GPSCon graphs of this significant improvement during the > test next week if there is interest. > > Bye > Said > > Sent From iPhone > > On Dec 29, 2012, at 18:56, Bob Camp <[email protected]> wrote: > >> Hi >> >> The interesting thing is that you sometimes can get a position hold receiver >> to report it's estimated location…. Not so much on current product, but on >> some of the old stuff. >> >> Bob >> >> On Dec 29, 2012, at 9:51 PM, Jim Lux <[email protected]> wrote: >> >>> On 12/29/12 6:34 PM, Bob Camp wrote: >>>> Hi >>>> >>>> The gotcha is that often the "navigation" and "timing" receivers are >>>> identical in terms of hardware. There is no upgraded hardware in the >>>> timing device. >>>> >>>> When you put a receiver into position hold, you are telling it "I don't >>>> care about the location solution". It reduces the weight of that part of >>>> the filter. Yes, that's only one way to look at it and there are other >>>> ways to look at it. >>> >>> >>> or, another conceptual model is: I'm fixed, I know where the transmitting >>> satellite is, and can calculate range and doppler a priori, so anything >>> else must be local clock variation and propagation. And you can average >>> out the propagation among multiple satellites (or use one satellite as your >>> timing reference).. >>> >>> Particularly if you are post processing and have precise ephemeris data for >>> the satellites.... >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> 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.
