Reach RS for GCPs and UAV mapping

I am so confused with all this info about the Reach RS and would ask for some clarification. Apologies if these are simple questions that have been answered but I have spent like the last few days reading all the articles and I’m a bit confused still.

I would like to use the Reach RS system to place and fix GCP positions for aerial mapping and surveys. From my understanding thus far:

I would require 2x Reach RS units. 1 acts as a Base station, and the other acts as a rover - to move around on the GCP locations and obtain the gps fix.

What is confusing me now, do I need to have access to wifi or 4g networks to operate? I operate in deep dark africa and often times have no wifi or cell phone signal for 4g etc. Would the reach still work out here? Is the wifi network they are talking about a closed network between the reach rs base and the reach rs rover?

Next when I go to the shop to purchase the Reach RS system, there are a few options. One is Reach Mapping kit - this is confusing to me as it is meant for mapping but only contains one Reach RS unit but says it’s an RTK mapping kit. Should there not be two Reach RS units in there?

Im presuming to be able to place and fix GCP coordinates with the reach system, i need to purchase two Reach RS units only. Or do I need to get an RTK kit as well as two Reach RS units?


No, you can use LoRa which is buildt in to RS. LoRa covers the connection between base and rover.
LoRa has its limits, like obstacles. And range depends on your area.
For longer range then what LoRa can manage, you could send correction over internet or get better antennas
But from what i read, you could do this with post processing (no radio needed). Search for Static or kinematic post processing,

Yes. But getting connection to the world around is a different question.

I am not sure what you are referring to here.

You can connect RS to a CORS station and do LIVE RTK with correction sent from a paid service that is sent over the internet. Or log for post processing later. You download data from a free or paid refrence station and process GCP later at home. (you dont get the accurate absolute coordinates before yuo get home and process rover and CORS log)

You do not need two RS to survey GCP. Read my comments above, its related.
Also read up on RELATIV and ABSOLUTE coordinates. here

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I’ve just looked online and the CORS network doesn’t have a station in Zimbabwe or anywhere nearby. This would not work… Unless it’s called something else here? Complete newbie sorry.

It could be called something els. Search for national positioning system or refrence station
@Luke_Wijnberg might have an idea, but as i remember it`s not much to choose from

I have just asked a surveyor friend of mine and there is no such system. The old method of using trig beacons to perform site calibrations is used where I live.
Take 3 known trig beacons and use their coordinates to triangulate and calibrate your measurements to make them accurate.

Hi Mike, The use of 2 Reach RS units is only beneficial for absolute** accuracy if the base unit is either set up on a known location or is receiving corrections from a remote station. In your scenario, since you have neither of those options, you would need to first establish a known location by the means described to you by your surveyor friend and then you would be able to set up one Reach RS (the base) on that location and send corrections to another Reach RS (the rover) as you move around within the coverage area of the built in LoRa radios on the Reach RS units. For “Relative” accuracy, see Brent’s post below.

The Reach modules, like in the RTK kit, are just like the RS except with no built in battery, no built in radio, and of course no enclosure. In other words, much more DIY to get a working setup.

[**edited to mention absolute vs relative accuracy]

Hello. Sorry to add confusion by giving another answer. The comment was made that the Reach RS base station is only useful if it’s set up on a known point or is receiving correction. I would beg to differ somewhat, as I am planning on doing a survey tomorrow with GCPs that will have neither a known point or live corrections. The base can sit somewhere close to where you’re surveying and give your rover it’s corrections. This is pretty much what you need if you want to make use of Reachview’s “Survey” feature. If you don’t need this, and want to collect points by “logging” then you aren’t using the “Survey” feature anyway. In my case, where I am just doing a topography and measureing features on a piece of property, I don’t need live feed from another source. My base station just will average its reading and assume this to be the known point. The accuracy for measuring within the property will be just the same as having a CORS station.

Brent, is that really true? How long would the base need to sit in order to resolve to be that accurate? Wouldn’t it rather just supply you with accurate distances between the 2 units? I apologize if that is in essence what you are saying. Perhaps the OP only needs limited relative accuracy.

Yes! The relative accuracy “within” the property would be the same. For example, I want to measure some topography and see where some buildings will be constructed relative to where some trees are located. I just wanted to clarify that in a case like this a base station is useful even though I don’t have absolute accuracy. I will keep my base station logging it’s position and then I can post process that if I need to and shift my entire survey over by that amount if I want. Then I would have absolute “real world” accuracy.

Ok perfect. So then in that case - we have trig beacons situation all around the country and usually within a few km of each other. I’m not sure the exact spacing or distribution network, but if it was beneficial for 2 units; I would place 1 unit on a known trig beacon as the base station. And then use the 2nd reach rs as a roving station to then acquire the fix on certain gcp points?

If I am understanding this correctly - in terms of simple land surveys two reach RS systems, without a known base coordinate, would still give good or should i say better accuracy than a drone without any gcp whatsoever - the Reach base would establish itself and any GCPs would be accurate relative to the base, meaning better measurements than just using the drone accuracy of approximately 3m-5m.

If I am understanding this correctly then, perhaps a client requires an initial survey of an unknown area, without any known coordinates. I can utitilise the Reach RS as a base, establish control points relative to this base. Conduct the survey and output the results with the understanding that the accuracy is not absolute.

If the client turns around and requests absolute accuracy all that I would be required to do is get the exact coordinates of the Reach RS base by perhaps hiring a survey with RTK grade equipment, and then once I have obtained that exact coordinate, I can use the Reach RS to then ‘calibrate’ my initial results, and produce absolute accuracy?

Thanks very much for the help, making a lot more sense now.

Without further ado, that is yes to your questions and from what i can see you got the general workflow right.
Also could be an idea to compare the accuracy of the beacons by measuring it against the other beacons.
Oh, sorry if i jumped in and answered on behalf of them others :zipper_mouth_face:

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