I've just started looking into RTK GPS. My state has a Trimble network that I might use. My application is, weirdly, something a lot like the waypoints of old Garmin GPS handhelds for hikers, only more accurate. I need to be able to lay down a series of points as I drive (perhaps around 30 mph or so) to map out a street network.
However, as I look around trying to find something I can just drop into my car and pull the data from (SD card? USB port?) later on, I haven't seen all of the RTK goodness trickle down yet into something relatively brain-dead and simple to use for my rather small case. I am definitely seeing kits and modules, and some stuff built into high-end drones, but it hasn't seemed to make its way down to my level yet and I am a little curious as to why (or if I am just not looking in the right place for the right thing).
Well, $265 (+antenna $60), but I purchased an Emlid Reach M+ [1] for drone RTK experiments, and it has been pretty simple to use... comes with a really nice UI on the device and internal storage in the unit. Also their website has good documentation, which is helpful since there is a lot to learn about how to do RTK.
Found a local NTRIP caster (within 10 km, lucky I am in range of a public RTK2go one) and the Reach uses the mobile hotspot on my phone to connect to the caster. After a couple seconds to minutes, it settles down to a 10-12 mm accurate fix in lat, lon, alt, and is kinematic so it maintains the accuracy as I am flying the drone around. It records the whole thing internally, or you can have various output modes like standard NMEA over serial, or bluetooth to your phone.
Also, I have used it to record data internally then post-process it for PPK using the county's publically-available RINEX files [2] and Emlid's RTKLIB fork [3].
Surely that little only gets you single-frequency receivers? So you'd be waiting around for 10 minutes to resolve ambiguities every time you got near a tree, bridge or building?
Or can you get multi-frequency receivers for that little these days?
Do you happen to know a good introduction to how one would use it? I've looked at tools around it a few times, but always didn't find the point where it made "click" on how to actually do anything with them.
Take a look at rtklib.com for software and instructions on https://wiki.openstreetmap.org/wiki/RTKLIB. There are quite a few u-blox receivers that work, also receivers from other brands. If you want to try dual frequency for improved accuracy, u-blox launched an affordable dual frequency chip in 2019.
You set up the base station over a known point, and now your rover unit can give you cm level accuracy when it's within range of the base station (UHF radio range generally).
For a practical application, let's say you wanted to lay out crops for a small hobby farm. This can make getting your base station set up, because you might not care as much about absolute location, which would require finding a surveyed benchmark. Instead you put your base exactly on the corner of your plot, and after setting up a local grid system you can now exactly layout your farm according to your plan. You simply walk around with the rover unit and can get real time cm accurate "coordinates."
