[time-nuts] nuts about position

George Watson watson at sierracmp.com
Wed Apr 25 11:06:34 EDT 2018


Create your own DGPS?

Trimble is good at this.

George K. Watson
K0IW

> On Apr 25, 2018, at 10:56 AM, Tom Van Baak <tvb at LeapSecond.com> wrote:
> 
> List -- I had a recent query by a researcher who would like to pinpoint the location of his telescope(s) within 0.3 meters. Also (he must be a true scientist) he wants to do this on-the-cheap. He may have timing requirements as well, but that's another posting.
> 
> So I toss the GPS question to the group. Surely some of you have crossed the line from precise time to precise location?
> 
> How easy, how cheap, how possible is it to obtain 0.3 m accuracy in 3D position?
> 
> When we run our GPSDO in survey mode how accurate a position do we get after an hour, or even 24 or 48 hours? And here I mean accurate, not stable. Have any of you compared that self-reported, self-survey result against an independently measured professional result or known benchmark?
> 
> Do you know if cheap ublox 5/6/7/8 series receivers are capable of 1 foot accuracy given enough time?
> 
> If not, what improvement would -T models and RINEX-based web-service post-processing provide?
> 
> It that's still not close enough to 0.3 m, is one then forced to use more expensive multi-frequency (L1/L2) or multi-band (GPS, GLONASS, Galileo) to achieve this level of precision? If so, how cheaply can one do this? Or is the learning curve more expensive than just hiring an survey specialist to make a one-time cm-level measurement for you?
> 
> Something tells me 1 foot accuracy in position is possible and actually easier than 1 ns accuracy in time. I'm hoping some of you can help recommend solution(s) to the researcher's question or shed light on this interesting challenge.
> 
> Thanks,
> /tvb
> 
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