Hi Indeed true for most non-geodetic gps units. Put another way - true unless you have a lot of money.
Bob On Sep 9, 2012, at 7:25 PM, b...@lysator.liu.se wrote: > Hi Bob, > > Probably true for Motorola Oncores. Not very true for geodetic receivers. > > Until you have a receiver clock that is on par with the satellite clocks > AND you are short on visable satellites. This might be true if you can > load up a modern cesium in your vehicle, and go for a downtown "urban > valley" type of scenario. > > On a stationary site, your expensive clock will not matter to much, since > your solution is already pretty over-determined with some 60 measurements > on each epoch. (9 GPS +6 Glonass)*2(L1/L2)*2 (code + phase) > > -- > Björn > >> Hi >> >> Position accuracy and timing accuracy are two very different things. >> Firmware is optimized to improve either one. "Position" firmware is often >> pretty poor for timing. >> >> Bob >> >> On Sep 9, 2012, at 5:05 PM, Chris Albertson <albertson.ch...@gmail.com> >> wrote: >> >>> On Sun, Sep 9, 2012 at 1:14 PM, <b...@lysator.liu.se> wrote: >>> >>>> True for a cheap oem navigation receiver. Not true for a geodetic >>>> quality >>>> receiver, who usually have some options (external frequency input, >>>> PPS_in) >>>> to make them the best timing receivers available. However they are much >>>> more expensive than the typical single frequency timing reciver. >>> >>> I looked at every link and can't see where they give a timing accuracy >>> spec on the PPS with respect to UTC. Possition accurracy is very >>> good and we might assume the timing is as good. But they don't say it >>> is. What's interesting is these GPSes will accept an accurate clock >>> input in order to give better location data. That is the opposite of >>> a timing GPS where you tell it accurate location data so that it can >>> get better timing. Cutting down the unknown in one lets you do >>> better in the other. I assume these all cost well over $50. You can >>> get a pretty good timing GPS for $30 and it WILL have the PPS error >>> specified. >>> >>> To the OP. None of this matters a lot because PPS is a standard input >>> signal. It is easy to swap out a GPS receiver later. Same with the >>> OCXO. From a control point of view they are all pretty much the same. >>> You can swap them out later >>> >>> >>> Chris Albertson >>> Redondo Beach, California >>> >>> _______________________________________________ >>> 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. >> > > > > _______________________________________________ > 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.
