The Area Measure app works with receivers from any maker that speak the standard protocols. Check these before you buy.
Must have
- Bluetooth LE or Wi-Fi (TCP). iPhones and iPads cannot connect to classic Bluetooth (SPP) receivers, and the app uses the same two connections on Android. Look for "BLE" or "Bluetooth LE" in the specifications. The app recognizes the common BLE serial profiles, such as Nordic UART, automatically.
- NMEA 0183 output, with GGA at the least.
Should have
- GST messages, so the app can show the receiver's accuracy estimate.
- GSA and GSV messages, for the sky plot and the satellite counts.
- RTCM 3 input on the same connection, so the app can pass NTRIP corrections to it, unless the receiver has a correction source of its own.
- Multi-band RTK (L1 + L2 or L1 + L5). Multi-band receivers fix within a minute or so and keep working farther from the base station; single-band ones are slower and less robust.
- All four satellite systems (GPS, GLONASS, Galileo, BeiDou), for more satellites in view.
Also worth having
- A pole mount, so the antenna is above your head and over the point you are measuring
- A battery that lasts a full day in the field
You will also need corrections
A receiver reaches centimeter accuracy only with RTK corrections from a nearby base station. See Set up RTK corrections (NTRIP).