Hi there! In one of our first posts in this category, we shared thoughts on choosing between your own base and NTRIP service for RTK setup. As the first option has already become a fixture, let’s focus this time on the setup which involves the use of a rover and an NTRIP service.
Such a case is indeed a good pick when there is proper cellular network coverage and you want to be more flexible in the field—it’s easier to go around with a rover only, especially with Reach RX and our new survey pole with a smartphone mount. Let’s look at the workflow!
First, you need to subscribe to a network RTK correction service that provides the reference station data—you’ll get the same high-precision surveying results as such services always provide absolute accuracy. Of course, it’s necessary to make sure that the service you choose indeed meets your needs. To help you with the latter, we’ve recently published a tip that sheds light on all the details of such services.
Second, you need to configure your Reach RX to receive corrections from the chosen network correction service:
Enable Bluetooth on your control device and find your Reach RX in Emlid Flow.
Tap Correction input and configure Reach RX to receive network corrections over Bluetooth.
Tap Add profile, fill in the information from your NTRIP provider, and don’t forget to tap Save.
Provide Reach RX with a clear sky view.
Make sure that your Reach RX is receiving corrections. With Reach RX, it is easy—just watch the Status LED color. Once it’s green, you have FIX and can start surveying!
The process is almost the same for all the other Reach receivers, internet connection setup is the only exception—check the Working with NTRIP guides in our docs to get more info.
And what about you? Which setup do you prefer—using your own base or getting corrections from an NTRIP service on your rover?
P.S. If you haven’t seen it yet, our previous post was dedicated to the benefits of using Emlid Account.
Hi I have a question about how to go about doing a version of this in that we are a paving company in Victoria bc and want to purchase 2 Emlid rs2 as a rover and base to collect mostly 2d surfaces for paving but like the ability to do more as we grow
What I’m trying to consider is do we need to run a rover and base at each location or could we set up a permanent base at our office and go out and do data collecting with just the rover rs2 or the rx and a pole?
In a productive way?
I have a general question about using a correction network and my RS2 rover. Basically what I do now is set my base, RS2+ on a know point and send correction to my rover to set checkpoints and the drone when I fly the site. I was thinking about stream lining this process to just use the correction network for both so I don’t have to setup a base.
I’m thinking I can use the correction network and tie into a know point with my rover and adjust my pole height until I’m under 1/10 of the know point…closer to a couple of hundredths, then go shoot my checkpoints and grid at that pole height. If I need to make vertical adjustments to my point cloud I can do that in Pix4d and or Agtek.
Does that seem like a viable workflow?
I plan on testing it out tomorrow at one of our smaller sites.
Yes, you could certainly set up a base at your office with an RS2(+) and then use an RX or RS2(+) in the field by using Emlid Caster
provided your baselines from the office to the field are acceptable.
Thanks Dave. I was thinking more along the lines of not using a base for correction and just using our correction service here in Texas, then adjust my rover pole height until I’m dialed into the elevation of our known points. Then go shoot my checkpoints for Pix4d and my grid for Agtek.
Does that make sense?
You could certainly use the Texas network for all your rover work. But if you have a known coordinate and use that for your base, your baseline will be much shorter, usually. And that will lead to more precision.
Yeah, I guess I didn’t describe what I want to try very well. I currently use my base on a know point for correction for both rover and drone. Instead of using a base I’d use the NTRIP service here in Texas. I use it on occasion when I don’t have known points to set on. I’m thinking I can adjust the pole height on my rover until I’m dialed into the known elevation of our BM’s, then shoot some checkpoints and a grid…I use the grid to validate my pointcloud in Agtek. If i need to make any adjustments I do it there.
Just thinking if I adjusted my pole height that would set the baseline for my grid and checkpoints save me some time setting up my base.
The RS2+ sim support is usually not very good and I end up hanging my hotspot on the base to connect to the Caster service…same cell provider just crappy latency using just the cell support in the RS2+.
If I’m connected to the Texas network I use the stake out option in the reach app, horizontally it’s usually right on with the BM’s provided to me by our survey guys, vertically it’s usually never under 1/10 unless I adjust my rovers pole height. At that point I can get to within a couple of hundreds of the BM’s elevation.
Does that make sense?
Curious… if your horizontal is within tolerance, but your vertical usually isn’t as much… say your Bench Mark (BM) is actually for example 700’ (orthometric height) per surveyor, record, NTRIP or CORS, but when you measure it says 700’ 3" above the BM (versus actual 700’), do you lower your rod 3" so it shows 700’ to stake your point(s)? Sorry, curious, haven’t heard of doing this and wonder if it’s OK to do this or if it affects measurements?
Yep, that’s exactly what I’m saying. We get control, BM’s, from another survey company. Most of the time they don’t box in the site so our survey guys go out and level loop some in base of what we get from the other survey company. I get those and create a Emlid project. When I get to the site I use the stake out option to find them if they’re not visibly marked. What I’ve found using NTRIP for corrections is elevation never matches the elevation for the BM unless I adjust my pole height…like your example. Right now I just do this to find the BM’s. I usually set my base on one of those and send the corrections to emlid caster and use that for correction for my rover setting checkpoints and the drone for flying the site.
I was just thinking about removing the base on the known BM from the equation and just going with NTRIP for corrections for both rover and drone. I was thinking adjusting the pole height on the rover when tying into one of the BM’s would set me up to shoot in my checkpoints and the grid. I use the grid to check my point cloud accuracy from the drone. If the drone is off a bit from the grid I can adjust that in Agtek.
I haven’t tried this method yet, was planning on testing it out tomorrow on one of our smaller site.
I’m not a survey guy by any means, only been using Emlid for about a year or so that’s why I’m asking here. You guys know way more about this stuff than I do.
Does that make sense or am I way out in left field?
Do you check multiple points when running off of Texas NTRIP and they are all off by the same amount? If so, someone, somewhere has something off. If you test several, and the height offset varies +/- then you don’t want to hack your pole height to match any particular point. And, if you pick one and adjust your rod height to make the offset as small as possible and then use that to feed a rover and your drone mission, aren’t you risking making things worse?
If you are finding a consistent offset, I would focus on pinning down where that offset is coming from. Not applying it to your inputs. As you mentioned, you can adjust the processed surface in software.
Do you know how the vertical coords were established ?
This could be a case of gnss vs terrestrial methods in the determination of the vertical components of the points.
Terrestrial level loops are more precise than gnss methods.
Also, where were the elevations determined from and what vertical accuracy was the original benchmark that all the points elevations were established from ?
There’s all kind of variables here that are not known. I would contact the surveyor who determined these points and ask how they were established and what kind of vertical accuracy was the benchmark that all this is referenced from.
Adjusting pole heights to match the control is not advisable. As Dave mentioned, you are introducing another layer of error in your measurements and the act itself doesn’t make any sense.
Typically, vertical accuracy of gnss methods in a network RTN or local base RTN is approximately 2-3 cm. Terrestrial level network accuracies usually are around 0.5 cm or less depending on the size of the level loop and the method used in determining the level network.
You need to ask a lot of questions to the data providers and also do some studying concerning the correct methods of data collection in surveying.
I don’t know how the points that are provided to our survey guys are established, I’m assuming they were using the terrestrial method. I say that because every time I us the stake out option vertical is never under 1/10…if I’m using the Texas correction network for my rover. Once our survey guys get those points they validate some of them and use that to set more…if needed. From what I know they level loop everything they set back to one or 2 of the points they validated. Looking at their gc3 file they are typically a couple thousandths off.
I’m gonna do some testing today at one of our smaller sites. I have 2 BM’s I’m going to try to tie into using the network for corrections then set my base on one and tie into the other recording pole height for both. I’m also going to shoot in some checkpoints using both methods.
Like I said I’m not a survey guy but I did stay at a Holiday Inn last night.
Thanks for all the input. I’ll post what I find later today.