Hi On something like a phone, you are likely looking at a combination of what the phone does and a contribution from “the cloud”. Part of that cloud contribution depends a bit on the carrier and how well they are doing their part of things. In one area you might have surveyed towers and a full GPS / Glonass synthesis. If you bought your service from Crazy Bob, there may be no local correction information. Forget about GPS / Glonass in that case (at least in the US).
Bob > On Apr 25, 2018, at 10:46 PM, Brooke Clarke <bro...@pacific.net> wrote: > > Hi J: > > I had a number of survey stakes I placed using a manual transit and tape > measure and hired a local surveyor to tell me where they were and also tell > me where my GPS antenna was located. > > He setup a GPS antenna on one tripod and a (Trimble?) combined GPS-total > station on another tripod and ran a cable between the two. After some time > (tens of minutes or ??) he used the theodolite to sight my stakes and the GPS > antenna. I got a report back in a week or so. Total cost a few hundred > dollars. > > I'm in the process of looking at how accurate the GPS is in my new LG G6 > phone. > > -- > Have Fun, > > Brooke Clarke > http://www.PRC68.com > http://www.end2partygovernment.com/2012Issues.html > > -------- Original Message -------- >> I think to really be confident about a position you really need the >> dual-frequency data (or that data from a nearby reference station), >> otherwise you could end up in a situation where you're consistent, but that >> consistency has a bias. IIRC, anyhow -- I'm not sure how the math actually >> works out. >> >> Anyhow, I play around with PPP stuff on occasion, and the last run I did was >> in November using the Novatel OEM628 kit that was briefly available for >> cheap on eBay, and the included 702-GG antenna (which, conveniently, has >> calibrations available). Running a day's worth of data through CSRS-PPP >> produced sigmas (95%) of 0.004m latitude, 0.008m longitude, and 0.024m in >> elevation. I've done some shorter runs since then that appear to fall in >> that same range ... I really need to do a few more full runs and see what >> kind of variance there is. >> >> At any rate, theoretically you can get ^^^ that close, anyhow. CSRS even >> takes solid earth tides into account, though I didn't do that because I was >> never able to figure out which specific type of solid earth tide data I >> needed. I imagine there's still some issues with any given datum being >> somewhat imperfect, as far as altitude is concerned, and I don't really know >> how to correctly deal with that if exact altitude matters. Maybe we should >> all just agree to use XYZ/ECEF coordinates for everything and give up on >> this whole altitude thing altogether... ;) >> >> (As an aside, I've been tempted to get someone to come professionally survey >> my antenna and tell me where it _actually_ is, so I could see how well I >> could actually do with my GPS kit, but I imagine it's pretty expensive -- >> anyone happen to know what getting that kind of thing done actually ends up >> costing?) >> >> -j > > _______________________________________________ > 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.