Two Reach RS+ or Reach RS + with Reach M+


I wonder which option could be better for what i want: obtaining accurate positioning of different points (hundreds) in a photovoltaic solar farm.

The two options i discuss are:
A) 2 Reach RS + (one as a base and one as a rover).
B) 1 Rs+ and 1 M+ (base and rover, too).

The surveying is going to be done by workers, not with drone.

As far as I know, option A) would be more expensive but easier to carry out, due to the possibility of connecting both RS+ via LoRa.
Anyway, I wonder if the other option could be more affordable and, maybe, not very difficult to implement.

I have been said that LoRa is not supported by M+ (what would imply that distance could be an obstacle for my surveying). In the other hand, I read in a post (Radio type) that it could be possible to connect Reach M+ vĂ­a RFD 868+ Modem (, for example.

Anyway, I wonder which advantages would have each option and what would you recommend me or if there could be a better one than ones I gave.

Thanks in advance.


For surveying, 2 RS+ is better.

It is not more accurate, but better in that you have 2 environmentally sealed units that are ready to go and easily mount on tripods or poles.

For surveying the solar farm, I don’t think you really need LoRa, as you could just post-process your logged data. If LoRa works for your location/environment then it is nice information to have while sitting and collecting a point.

Last, but not least. You could just buy two M+ and antennas for a lowest cost option. Also, LoRa radios for the M+ will become available at some point.

Thanks for your response, bide.

I think i was confused about LoRa. I thought it was the way through which both devices would communicate so as to achieve more accuracy.

I would be interested in the more affordable option you talked about: 2 M+ and 2 antennas. Do you mean that it would be enough if i use M+ modules with “Tallysman Multi-GNSS Antenna”? Or another kind of antenna? I thought that I would need external radio modules so as to interconnect them.
Could I send the obtained information (accurate coordinates) to an smartphone while doing the surveying using this modules? What more would I need?

Thanks for the info, in advance.


There is not much difference between the RS+ and M+ units. Think of the RS+ as a M+ with Tallyman encased in a compact housing with included LoRa Modem and Powerbank…

That said,
you can use two M+ Units with the Tallysman Antenna, Two Powerbanks and two External Modems, place it in a sealed case and you have something pretty similar.

I often used a RS and Reach Module (old Modules) where the RS was the base, because of the nice housing and possibility to mount on a tripod and the module was the rover.
Data correction were sent via a cheap 868MHz Radio (for Pixhawk) on UART .

However, it is cheaper, that way but you have to fiddle around a bit. That said, I just bought another RS+ unit so that I have two RS/RS+ receivers which I can comforably use to take Ground Control Points, whereas the Reach Module will be mounted on UAV’s or autonomous rovers.

As you’ll have to learn quite a bit anyway about RTK and the Setup; maybe it’s better to stick with two ready to run units RS+. If you want to invest some time, are not afraid about electronics and can build your own cases… you can move on with rhe M+ module. Just be prepared to invest some time for the setup and be prepard for some in-situ debugging from time to time :wink:

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Like @sebastian_achilles was saying, yes that is all you need to buy from Emlid. The rest you can get locally (batteries; antenna ground planes; a smartphone or tablet with Wi-Fi).

You do need radios to interconnect them for RTK. However, you don’t need radios if you are going to do PPK (post-processing). For that, you just download the files from each receiver and process them on your computer.
Doing PPK is cheaper, It will give you a small advantage over RTK in that you will get the best results. The drawback is that you don’t get to see the results in real time. You see them later after you run the post-processing job.

Yes, if you have radios or a cellular data connection at each end, then you can do RTK, and you can send the RTK output to a device over: serial(uart), Wi-Fi, or Bluetooth.

I’m very grateful for all the info you gave me. I think we will eventually choose to buy 2 RS+ units, even if it is more expensive. It will be easier and more resistent to environmental conditions.

Thanks very much for your help!


For us it is more interesting to do RTK, since we need to get results in real time. As I said to @sebastian_achilles, we eventually decided to buy two RS+ devices.

Anyway, thanks very much for all the info.


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