[time-nuts] nuts about position

[Michael Wouters]

The US-based services work fine with non-local data. I've  used them with
Australian locations. The IGS network is global so nearby stations in the
IGS network are used for the solution. There are non-US services too, like
AusPos.

The topic of better antenna coordinates seems to come up now and again. It
might be a good cooperative  timenuts project to put together a travelling
receiver system that could be used to survey antenna positions. With a bit
more effort, it could also be used to calibrate delays, where receiver data
is being post-processed for time-transfer.

Cheers
Michael

On Fri, 27 Apr 2018 at 8:02 am, Bob kb8tq <kb8tq at n1k.org> wrote:

> Hi
>
> If you shop for a while on eBay, you can find older L1 / L2 survey
> receivers for < $300 and
> an antenna that will work for them for < $100. Yes it will take a bit of
> heavy duty shopping and
> some level of “wait and see”.  How well they work and how much of a pain
> is associated with
> this process ….. who knows.
>
> Once you have a radio you can get data out of, submitting the files to any
> of the free services
> in the US is pretty easy. If you are outside the US, you may still be fine
> or you may have a tough
> time with the data reduction.
>
> Bob
>
> > On Apr 26, 2018, at 1:04 PM, Scott McGrath <scmcgrath at gmail.com> wrote:
> >
> > Swiftnav has a centimeter accurate multi band receiver RTK-585. Its
> about 600 bucks minus antenna.
> >
> > You would need a choke ring antenna to get centimeter accuracy i think
> but receiver with a quality timing antenna will provide necessary accuracy
> >
> > On Apr 25, 2018, at 8:06 AM, George Watson <watson at sierracmp.com> wrote:
> >
> > 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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