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PPK
Today I needed to get started finishing a BLA plat, I needed some utilities located to write a simple easement to cover them. Instead of setting up a base I used my rover in PPK mode and tied it to the local CORS station. My rover is an R-8 and I’m using a TSC2 with surveyor controller. I put it on the truck as I drove to the site, let it get fixed (I have it set for 3 minutes to fix), then set it on the range pole with the DC and walked around the site locating the points. For this I gave each point a static location of 15 sec. That can be shortened to 2 sec or even 1 sec but I feel better with the 3 epochs of 5 seconds each.
Walking back to the truck I pass by a property corner so I sit on it and locate it for the same 15 seconds as a check.
Download the CORS into TBC and then download the job file and hit process baselines, they all process and fix. Send the points to the C3D drawing and look at the property corner check which is less than .04′.
We don’t have RTN data here so this is how I do it without a base.
The CORS is close to this site, often I’m far from any CORS and for that you have to use a longer session time, not a longer point location time, but leaving the receiver fixed for a longer time than the 10 minutes I did today. That is the key.
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6 Replies
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I ppk everything I do. I use a 5800 with a TSC2 running survey controller. I use two 4700 base stations as the Cors stations are too far away (50 miles). Usually I’ll do 40 sec. occupation times with 5 second epochs. I have no problem with closure kinda like what your showing in your example. Not interested in RTK. Oh well old habits die hard.
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With Javad, we collect both, RTK and ppk, simultaneously. But, ppk data isn’t available, until we get to WiFi signal. This can be through the cell phone, or any lan wire, or any access to the internet. It’s a component of DPOS. (That’s Javad’s opus)
Question. Are you getting ppk in the field? What is data flow?
We are surveyors. I am forever curious, and want to keep up with technology. I tried very hard with my old topcon gear, to get it to do both, simultaneously. Never got it, except via a manual process, of turning on raw data at base, and on/off for each one at rover. I could not do it via software, controlled through the data collector. I tried. I think it had part of the software interface built, but not functioning.
Thanks
Nate
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I have a 5700 base 5800 rover combo. They work great, I usually use them RTK but they do well in PPK. I would rather RTK everything but it isn’t always efficient. 50 miles is a bit far to use CORS and 40 second locations. However a continuous topo might surprise you, if you let it cook long enough. If you ever do a continuous topo in PPK and you have an hour or so into it you could try processing it against the CORS 50 miles away, you may be pleasantly surprised.
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>I have no problem with closure
How do you define closure on GPS data? I didn’t think that term was commonly used in that context. Do you mean agreement of repeated observations on a point?
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Trimble allows you to data log as you do RTK, however, the understanding with those sessions is that you don’t lose lock as it’s done. That slows everything down for most tasks. If you lose lock then you need to wait to re-fix the rover and that is set for 3 minutes on mine, so……..
That is for special situations.
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Yup, my measurements repeat on previous shots. Give or take a couple of hundreths. If I did RTK, I’d still post process to check my results. That’s just me.
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