I’ve got an RTK Express (with the L1/L2 antenna) and it works great, the only downside is that every time I move it, I’ve got to leave it in place for 3-5 minutes before the signal “settles down” and I can get 1 foot accuracy or better (which is plenty for my needs). The area where I’m using it (Allenspark, Colorado) has -zero- cell phone coverage and -zero- WiFi. It’s high altitude and not very tree-dense so there shouldn’t be any problem getting the satellite signals.
(1) is that amount of time expected, given my setup?
(2) if I get a second RTK Express and use them in a base/rover configuration, will that speed things up? There’s an official survey point where I can put the base unit and make all my measurements can be relative to that point.
(3) how accurate are the elevation measurements I’m getting? Again, I could use the elevation at the official survey point as a known value and only use the rover for elevation values relative to the base.
Right now, you use your RTK Express in the middle of nowhere, without differential corrections. Correct? What dynamic do you have selected? Are you in rover mode or base mode? What do you mean by the signal “settles down”? What kind of fix do you get? What is the accuracy announced by the RTK Express?
(1) is that amount of time expected, given my setup?
Yes. The device is resolving many unknowns without external corrections.
(2) if I get a second RTK Express and use them in a base/rover configuration, will that speed things up? There’s an official survey point where I can put the base unit and make all my measurements can be relative to that point.
Tremendously. You would see an RTK Fix within a few seconds of receiving corrections from the Base. Your accuracy would be excellent (sub 100mm or better). But note that official survey marks often require a bit of work to get their modern lat/lon. See our work here using an NGS mark.
(3) how accurate are the elevation measurements I’m getting? Again, I could use the elevation at the official survey point as a known value and only use the rover for elevation values relative to the base.
I believe there are some other better posts by @rftop on the forum diving into the science, but elevation is the worst of the three (lat/lon/elev). As a rule of thumb I double the reported HPA. So if you’ve got RTK Fix with a reported 14mm accuracy (this is achievable with an RTK Express) then the elevation accuracy would be ~28mm.
does SparkFun even sell a radio anymore that would allow the base and rover to communicate?
Depends on the distance you have between the Rover/Base. I recommend starting by using the internal ESP-NOW radios to get your setup working. Serial radios are the next step up. After that, LoRaSerials work but require more configuration work than ESP-NOW or telemetry radios.
Assuming that the survey point has a datasheet (adjusted control), this would be good head-start for occupying that point with a Base. The RTK Rover Solutions would inherit the same Reference Frame, Epoch, etc as the control if you use the published coordinates at your Base.
However, I don’t see many good choices for the area though on the NGS Data Explorer
If you’re not talking about 1 of the 3 Triangulation Stations, then you might as well Survey-In a Base and overwrite the Elevation from the datasheet for a “vertical-only” tie basically.
Considering your location/situation, you also might consider the StarLink thread for RTK via NTRIP ?
