Looking through the forum, there are a few threads that claim various maximum distances for RTK surveys using the built-in LoRa radio, ranging from a few hundred metres to greater than 20 kilometres. Of course, it’s always dependent on environmental conditions as well as terrain.
I want to give an extra data point from a survey we did last week.
Having used a Trimble R10 with a 2 watt internal radio (which often gives us possible radio reach up to about 10 km in varied terrain) for many years, I was a bit skeptical about the reach of the 0.1 W radio in the RS2+.
Last week, we did a UAV survey of an estuary and placed GCPs around the shoreline. This was our first real test of the system and I’ll show the results in the map below. The environment is (apart from the higher moisture content of the air near the seashore) relatively good for radio transmission, since the topography is quite low (mainly dunes) and most measurements had line-of-sight to the base. Distances of up to about 3 km didn’t pose a problem, even though line of sight was not always given for these points. However, one point (which the Trimble GPS did without a hitch) was less than 2 km from the base, but located right at the bottom of a steep dune that stood between the point to be measured and the base GPS. I attribute this to the relatively weak radio signal from the LoRa radio. But all in all, we were quite impressed for settings like this and the radio poses less of a problem than we had feared.
As far as the setup goes, we did not use an extended aerial on the base, but just used the down-facing stubby antenna that comes with the kit.
I hope our results might be of some use for people like us who were looking for real-world experience of the radio distances that can be expected.
PS: We did not try to max out the reach of the radio, but rather measured points we had to measure for our project. So, it may well be that the radio reach extends much further. Regard this as a minimum possible distance in fairly un-challenging (i.e. no large stand of trees, etc) conditions.