Emlid

Community Forum

Reach under canopy & in agricultural field


(Brian Lindens) #1

We’re looking at getting a Reach RS+ or RS2 and was curious what users experience was like under a couple different situations (we do ground surveys). We do not need centimeter accuracy vertically or horizontally.

  1. In the bush under forest canopy. Currently we use a Garmin 64s for spot readings. For example, every 25 meters we’ll take a reading and note it in the GPS.

If we could replace this with a GPS we could hook directly up to our equipment, like the Reach, would be ideal.

  1. The most important application is running EM surveys in agricultural fields (very wide open) attached to an ATV going about 10 km/hr. Again, we don’t need super high accuracy (being off by a foot is okay). Commonly used receivers are the Hemisphere S321 (with antenna) or the Juniper Systems Geode.

For this we need continuous GPS readings as the ATV moves along.

The Emlid Reach RS+ was spoken of very highly, but another user suggested that a handheld GPS would give more accurate readings than a standalone GPS (although move surveyors in the agricultural space use only one GPS).


(Timd1971) #2

Wellll… if you think you are going to be going under and/or in and out of forest canopy, might as well get a RS2 or two if it justifies the cost. Before the RS2, i guess you’d have to reach deep for Trimble $$$$ etc.
But RS2 is a reality now, so it should be within reach.

But you mention you do not need a solid fix for cm accuracy. So you’d probably be fine with s RS+ or two.

I was around some foliage the other day with RS rover (with RS base) and lost fix and had float until i got back away from it as i needed cm accuracy…so yeah, a bitch and wished i had a couple RS2 at the time.

Again, the RS2 is very reasonable… if you have the cash its a no-brainer.

You could also use very long telescoping base/rover poles swinging & bending in the wind too. : /


(Brian Lindens) #3

Thank you for the thoughtful response.

While we’d rather spend less than more (duh), we have the budget for an RS2 (or two RS+s). What do you see as the major advantage to the RS2 over the RS+ in terms of foliage? I’ve looked over all the tech specs, but its a bit out of my wheelhouse.

And when it was floating, over what rough range was it moving? For us, not needing cm in either application, if it was a foot either way in foliage that’s good enough for us. We do gravity surveying where we need that cm, accuracy but we do that infrequently and can rig a special setup to get around that (so not a concern).


(Gleb Gira) #5

Hi @intenna,

Reach units are based on RTK technology. It means that you need two devices (base and rover), in order to obtain a precise position. A base can be any Reach unit or NTRIP caster station.

In ideal conditions, both Reach RS+ and Reach RS2 provides almost the same centimeter-level accuracy with RTK. However, Reach RS+ is an L1 GNSS receiver. In regards to RS2, it’s multi-band. It allows RS2 to acquire fix faster, just in few seconds.

Reach RS+ require a clear sky view with no trees and other obstacles that can block the signal. Reach RS2 maintains robust performance in challenging conditions and will suit better for your purpose.


(Timd1971) #6

There you go.


(Brian Lindens) #7

Appreciate the responses, very helpful. I’ve had more discussions, and worst case we’re comfortable with being off by up to a meter. Now, that is NOT ideal, but under canopy we’re currently taking clinometer shots by hand which probably has roughly that level of accuracy. In our agricultural application we want a bit more accuracy, but being off by a couple feet is also okay.

Three follow up questions:

  1. If our base station has clear sky but our rover is under canopy, will that solve the canopy issue? I assumed not, but in the documentation it’s just a photo of a base station.

  2. In the case of using an Reach rover in an agricultural field, it has been suggested that a handheld GPS will be more accurate. But industry standard in that case is a Hemisphere or Junipers systems GPS (rover only, no base).

  3. Can we use a Reach as a base and our phone’s GPS as the rover (at least in the case of an open field)?

I should note, we don’t need to in-field processing, if that matters.


(Timd1971) #8

I am going to let someone with more canopy experience jump in… but my 2 cents is that the ROVER (RS/RS+) not only the BASE has to have clear sky view or you will lose FIX and drop down to FLOAT which may be fine for you? You’ll lose cm accuracy, but you don’t need it you mentioned… so it may drop down to a meter or more. You may be better off then with just a handheld then?

This apparently is where a multi-frequency receiver such as the RS2 will shine and still retain a FIX with cm accuracy when in troublesome areas a RS/RS+ will lose FIX. You could always get 1 RS2 and use a NTRIP CORS to connect to a base service? You will have to see what CORS is available in your areas of use and the cost. See if it justifies just getting another RS2 instead of CORS later? Or get a RS2, use CORS, then purchase a RS+ if CORS not an option and insufficient funds? But the RS2/RS+ combo will probably only act as L1 RS+ until you get another RS2 completing the proper pair for multi-frequency. You could look at the M+ and a LoRa add-on too, but personally that would be more headache and would regret just putting the funds toward a RS+ or RS2 ultimately.

You can’t go wrong with 1 (RS2 and CORS) or (2) RS2’s (BASE/ROVER and/or CORS) I would assume if encountering foliage a lot. Don’t forget, you’ll have to wait a bit also for the RS2 orders.
@agrimgalina may be able to provide you some feedback with his RS+ and NTRIP?

Hopefully someone with more foliage experience will help you here. (they are probably busy) : )


#9

@timd1971 Foilage is on my list for RS2 testing. I can’t be sure how soon it will happen though.


(Timd1971) #10

I kind of figured it would be. ; )

@intenna I think there’s a good chance @bide will have great results here either way with the RS2. So if you can’t wait until he gets to that part of the thorough process, you’re probably safe anyways. : )


(Christian Grüner) #11

Nop, it will not. It will be better than an uncorrected GPS, however. This is because of a better antenna and the corrections from the base.

I would really like to challenge that claim of a handheld being better. For the Garmin you linked to, it only receives GPS and GLO, and does not seem to even SBAS corrected, being a small, handheld device, the antenna is compromised as well.
Compare that to the RS+, you also have GAL and SBAS, and if you go to the RS2, you can even have the BEI constellation as well, all of with a more sensitive antenna, and all the benefits of Multifrequency.

Well, some newer smartphones provide the raw GNSS file, however, the antenna on such a device is severely compromised, and would be even worse than a handheld.


(Brian Lindens) #12

This has been incredibly helpful. This all started with another surveyor telling us that the Reach is a great solution and to just get it - it’s ended up a little more complicated!

If I can ask one final question, as we’re trying to figure out what to order. Our initial applications for the first couple months will be purely in a field on an ATV (in vineyards). Can we get away with a single RS2 as a rover? We’d need accuracy of ~3 feet horizontal/vertical, but again would not be under canopy. I understand we could use something like NTRIP as well, although I’m unclear if that’s necessary?

Then we could later invest in an other RS2 as a base for the under canopy work.


(David Hofer) #13

yes I believe that would be accurate enough for 3 feet accuracy , but lets see what the experts say first :wink:


(Timd1971) #14

Yes of course… BUT you have to use NTRIP CORS for the base if you do not have one for cm accuracy.

You need to look into that first to see what is available in your area and the subscription cost. If it exceeds $2000 year, might as well get another RS2 for base instead.

Basically using NTRIP CORS is that your receiving corrections from someone else’s base hopefully within max range over the internet. So you’ll need a cellular connection also. I.e. your cell phone sets up ite own hotspot you connect to.


(Timd1971) #15

Submeter accuracy with a Reach/RS/RS+. Probably same with only 1 RS2 (without NTRIP CORS) also?


(Timd1971) #16

That might be wise and save you TONS of headache when in difficult areas. It’s not like everywhere you need to work will always be clear sky view.

; )


(Michael Lambert) #17

I wouldn’t bet on this. Until you have at least a float condition you could easily be 3m to 5m and it will bounce around quite a bit which means that your survey will not be relative to itself. It’s a nice function of the units/software that we use as our primary at work is that it has a section of the GPS info that tells you your average RMS in real time. If I don’t have that least 8 to 10 satellites the area can easily be 15ft either or both horizontal and vertical.

Where are you located? At least in the US I know that you should be able to download Rinex data from NOAA and then do PPK. PPK doesn’t appear to be quite as easy for survey as it is with the Drone, but I am sure that there’s someone on here that can help with that.

https://www.ngs.noaa.gov/CORS/data.shtml