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Base Rover Newbie

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(@brad-ott)
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Posted by: @dmyhill

My real question is why are you switching off the network?

I am hoping for better vertical performance as well as under canopy performance.

 
Posted : 10/02/2021 5:35 am
(@dmyhill)
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@brad-ott

?ÿ

And using a base will do that, in my experience. The more the base and rover "see" the same constellation, the better the results. I think Javad was trying to get people to put them on their trucks for a while.?ÿ

 
Posted : 10/02/2021 10:54 am
(@bill93)
Posts: 9834
 

No doubt shorter vector length will improve performance when the limitation is iono/tropo differences between base or CORS and the rover, but I question whether it will help much under canopy where the problems are multipath and reduced signal strength.

 
Posted : 10/02/2021 11:06 am
(@dmyhill)
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@bill93

The vector length is not typically an issue with networks. The issue is how many sats your rover sees that are also seen by the base(s). With the newer multi-constellation network bases, this is mitigated and not an issue. If your network is still GPS or even GPS+GLONASS only, then there are many times when it is useful to have a base station set up close to your work.

 
Posted : 10/02/2021 11:26 am
(@brad-ott)
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Posted by: @dmyhill

If your network is still GPS or even GPS+GLONASS only

My situation here in Indiana.

 
Posted : 10/02/2021 11:30 am
(@robertusa)
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@dmyhill Vector length from base station used is a factor for a VRS/RTN.?ÿ The network reduces the ionosphere effect from 1 ppm to 0.5, but the base line uncertainty still is from which CORS being used within the network.

 
Posted : 22/02/2021 1:58 pm
(@williwaw)
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Posted by: @brad-ott

I am hoping for better vertical performance as well as under canopy performance.

That's the primary reason I don't rely on our VRS system here. Precision drops quickly around obstructions like canopy for me. The second reason is when I run into issues like loss of radio, loss of cell signal, questionable solutions, having base data relatively close by allows me to post process and play with noisy data to get something I'm more comfortable relying on.?ÿ

 
Posted : 22/02/2021 2:10 pm
(@jmh4825)
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Purely VRS with one rover for 5 years, now I'm in the same boat with the base/rover newbies and have a few questions.?ÿ It's hard to ask your mentors when none of them have any GPS experience; therefore, I'm turning to here.

1- How much error will I normally see per say every 1000'??ÿ I know accuracy degrades with distance from base. For example, I setup base (get coord. from VRS that compares to OPUS) and tie down a NGS Mon. 3000' away.?ÿ It misses 0.20' H, 0.30'V.?ÿ Do I translate my base point to the mon. OR hold OPUS solution for my base coordinate.

2- Will OPUS give better/worse results post-processing a single point than other programs??ÿ I'm a Carlson user so I'm looking at Carlson GNSS.?ÿ How do I connect Base/Rover static data together or CORS with Base data??ÿ I've herd the term leap frogging by have no clue how this works. I've also had the OPUS Projects class but don't understand how this integrates with both base and rover.

I've got a long ways to go.?ÿ Any recommendations on SurvNet training or other ways to learn more? Books?

 
Posted : 16/08/2021 7:57 am
(@norman-oklahoma)
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1. Misses what? We would have to know a lot more about the quality of the VRS position and the conditions at the base and the NGS points. Also, is the NGS monument position in the same flavor of NAD83 as the VRS base point? With VRS the bases are (generally) well selected to be in the open.?ÿ With base/rover pairing sometimes the base is not so open. And the sky conditions at the base are just as important as the sky conditions at the rover.?ÿ

2. You may get a marginally better position by processing it yourself. Maybe. You can include more vectors in the solution and toy with the vector resolution more. The tradeoff for this very marginal gain in precision is a couple hours of work vs. a few minutes with OPUS. I've never found it to be worth it, personally.?ÿ?ÿ

 
Posted : 16/08/2021 8:31 am
(@rover83)
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Posted by: @jmh4825

Purely VRS with one rover for 5 years, now I'm in the same boat with the base/rover newbies and have a few questions.?ÿ It's hard to ask your mentors when none of them have any GPS experience; therefore, I'm turning to here.

How in the world do we have practitioners acting as mentors who are not up to speed on technology that has been around for decades?

Sorry, that was a rhetorical question, it's not your fault. But I recommend getting some surveying mentors who are actually familiar with surveying.

1- How much error will I normally see per say every 1000'??ÿ I know accuracy degrades with distance from base. For example, I setup base (get coord. from VRS that compares to OPUS) and tie down a NGS Mon. 3000' away.?ÿ It misses 0.20' H, 0.30'V.?ÿ Do I translate my base point to the mon. OR hold OPUS solution for my base coordinate.

2- Will OPUS give better/worse results post-processing a single point than other programs??ÿ I'm a Carlson user so I'm looking at Carlson GNSS.?ÿ How do I connect Base/Rover static data together or CORS with Base data??ÿ I've herd the term leap frogging by have no clue how this works. I've also had the OPUS Projects class but don't understand how this integrates with both base and rover.

There are far too many variables in each of those situations to answer definitively. But you're asking the right questions.

I've got a long ways to go.?ÿ Any recommendations on SurvNet training or other ways to learn more? Books?

It's great that you know there's a lot to learn about it.

GPS for Land Surveyors is a good start.

This online course from Penn State is a fantastic free resource.

However, they don't go into explicit detail about how best to occupy and observe depending on gear, conditions, etc...that is likely going to come from working with a seasoned and experienced person. We can certainly assist with certain very specific scenarios, but it's hard to come up with a one-size-fits-all methodology.

 
Posted : 16/08/2021 8:38 am
(@jmh4825)
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Posted by: @rover83

Sorry, that was a rhetorical question, it's not your fault. But I recommend getting some surveying mentors who are actually familiar with surveying.

Hope that insulting comment made you feel good.?ÿ That's the reason a lot of people don't ask questions, people like you degrade them.?ÿ Not everyone comes up with the latest and greatest equipment out there, that doesn't mean they don't know how to survey.

Thanks for the links.

 
Posted : 16/08/2021 9:00 am
(@norman-oklahoma)
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@rover83?ÿ

Those are great references. Very possibly the single best resource specific to base/rover RTK positioning is Hennings'?ÿ User Guidelines for Single Base Real Time GNSS Positioning

Also free for the downloading.?ÿ

 
Posted : 16/08/2021 9:07 am
(@rover83)
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@jmh4825?ÿ

That wasn't an insult, and it doesn't make me feel good. It's not at all out of line to expect professionals to be competent with the standard tools of their trade. GNSS goes back 30+ years. You don't have to have the latest and greatest equipment to keep up with current tech. It takes effort and dedication, but that's the responsibility we take on when we get licensed.

If an engineer didn't know how to use CAD, how could they adequately train an EIT on practical design in a typical engineering office? Or a GISP that doesn't understand geodetic coordinate systems?

 
Posted : 16/08/2021 9:32 am
(@jmh4825)
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Posted by: @norman-oklahoma

1. Misses what?

Misses the published coordinates for the NGS mon. Both are Nad83(2011) and coord. for NGS mon. is based on GPS observation. Just trying to determine why itƒ??s about double what Iƒ??d normally see with VRS and gauge if there is a rule of thumb for error and distance from base?

 
Posted : 16/08/2021 4:15 pm
(@skeeter1996)
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@jmh4825 I'm seeing that kind of error consistantly when comparing NGS published coordinates with OPUS.

 
Posted : 16/08/2021 5:08 pm
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