I've been very happy with my SMA20 purchase. Set up, pairing, and configuration is pretty simple. The receivers have worked well, and once everything is configured correctly, I've been getting consistent results. The included hard cases are a nice touch and make transporting the equipment to and from the field easy while keeping everything protected. Batteries in the receivers and data collector tablet last a long time. Anticipate about 60% battery usage for an 8 hour day. One thing that new users should be aware of is the tablet's GPS map. Just because your points appear to be in the correct location on the map doesn't necessarily mean the exported coordinates will line up correctly in CAD or GIS. If you're tying into State Plane coordinates, you'll likely need to calibrate the central meridian and adjust the false easting using a known control monument. Checking the northings and eastings of a point nearby in Google Earth against what northings and eastings the data collector is reporting will help you adjust the false easting if necessary. Once I worked through that, the exported data matched as expected. I would also recommend having at least a basic understanding of coordinate systems, projections, northings, eastings, and datums before jumping into RTK surveying. The equipment is capable, but understanding how coordinates are represented and transformed will make the learning curve much easier and help avoid confusion when importing data into CAD or GIS software. I've only owned the SMA20 for about two weeks, but I've spent a lot of time learning the system, testing workflows, and understanding how to integrate the data into Civil 3D. My plan is to use it for collecting existing ground data to create surfaces, designing proposed grading for a new building, staking building corners after grading, and producing topographic maps for stormwater permitting. Based on everything I've learned so far, I'm very satisfied with the purchase and feel it's an excellent value for the price.
