Hello everyone. I read the Emlid marketing material about the RS+ achieving cm level precission. It is within my start up company budget to buy them. Then over the past couple months, I have been reading to learn and watching every youtube video I could find about the RS+. Then, I come to this forum and I am surprised. It sounds like it is not possible to get anything resembling a professional level survey (drones in my case) with the RS+. It has been my intention to use two as base and rover to mark GCP’s and use PPK processing. NTRIP service where I live cost at minimum $3,000 per year. There is no way that I can make that cost pay off. Most of my work is inspection, and not anything that requires absolute accuracy. I do, however, want to be able to have the ability to engage in a project that requires absolute accuracy.
- So, in what scenario is an RS+ setup a good choice as a purchase?
- In Canada, is it possible without NTRIP access to achieve absolute accuracy with an RS+ setup? If so, using what processing technique.
If you have two units and some spare time, you record a rinex log and submit the file to Canadas NRCAN PPP service. That will let you know the absolute position of the point output in a choice of WGS84 or NAD83.
Accuracy wise Rs+/RS2 are on paper pretty much the same.
The RS2/M2 just does everything faster, and stays fixed in more challenging conditions. If anything you are doing is near trees, RS2/m2 is the better choice.
I wouldn’t recommend the RS+ unless you are on fairly flat open areas. The L1 only channel decreases the number of correction streams that you will get so it is easier to lose, fix and harder to gain it back. It really depends on the site itself. We started with an RS+ for drone work and it could accomplish about have to 3/4 of our work but I knew what to expect. Once the RS2 came out that was game over and we get repeatability about 0.04 ft horizontal and 0.06ft vertical so I would add about 25% to that as an for the RS+. The big names only get slightly better than the RS2(+) so unless you are setting benchmarks I don’t think there’s enough of a difference to compensate for the 600% increase in cost of something like Trimble or Topcon. I know they cost more but it will make you more efficient and with a happier brain at the end of each day.
The other thing to consider is because your workflow doesn’t include using a NTRIP correction service (ouch $3,000!) to shoot a known point for your GCP’s, there will be a limitation on the accuracy establishing a known point using a PPP service with the Emlid RS+ single band receiver. Emlid states that for the Emlid RS+ you can expect only about an accuracy of about 30 cm using a PPP service such as CSRS-PPP because of the limitation of the single band L1 receiver.
Quote below from Emlid’d PPP docs for the RS+ receiver:
PPP services overview
There are several PPP services available:
With Reach RS/RS+ you will get an accuracy of about 30 cm."
I agree with Michael & Potato Farmer that the Emlid RS2/M2 would be a better choice if your working in a more wooded/built up area. I’m so glad that I went with the two RS2 receivers back when they first came out, because I also was contemplating going with the RS+ receivers because of the savings with them.
They have served me well so far and I never could have as easily afforded the option of going with the big names in the industry. You might consider buying a RS2+ for the Rover along with a M2 with the LORA add on and third party antenna for the Base for a slightly cheaper setup. Of course it won’t be as robust as the all-in-one RS2+ solution.
Let me add a summary.
All Reach receivers can provide centimeter-level accuracy in RTK and PPK. Many of our users worked with Reach RS+ for placing GCPs – you can find some of these projects in our blog. Still, Reach RS+ is a single-band device, so it shows its best with a clear sky view 30 degrees above the horizon. And a multi-band Reach RS2+ is the best bet for tough environmental conditions.
Other than using NTRIP, you can obtain absolute accuracy in these ways:
Place your base on a known point, if you have one nearby. This way, you can get accurate positions with 2 Reach RS+ and no NTRIP service.
Find the base’s accurate coordinates with the PPP technique. But as @mark1st.john said, you can achieve only about 30 cm accuracy with single-band receivers. For centimeter-level accuracy with PPP, you can use a multi-band unit.
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