An RTK receiver reaches centimeter accuracy only with corrections from a base station near you. The Area Measure app has a built-in NTRIP client: it logs in to your correction service, passes the corrections to the receiver over the same connection, and sends the service your approximate position so it can pick a station near you.
If your receiver gets corrections on its own (its own NTRIP client, a radio link or a satellite service), you can skip this page. The app shows those fixes as using the receiver's own corrections.
What you need
Your correction service gives you:
- a caster host and port (often 2101)
- a username and password
- optionally a mountpoint; the app can choose one for you
You also need an internet connection on the phone, mobile data or Wi-Fi, for as long as you measure. The app passes the corrections on to the receiver as they arrive, and when they stop, the receiver soon drops back from centimeter level.
Where to get an account
- Government and university networks (CORS). Many countries, states and provinces run RTK networks, often free or low-cost after registration. Search for "CORS RTK network" with the name of your region.
- Commercial RTK services, paid by the month or the year. They cover larger areas and usually offer a network or automatic mountpoint that works anywhere in their coverage.
- Your own base station, or a community caster, if you or someone nearby runs one.
Corrections work best from a station within about 20–30 km. Farther away the fix takes longer, and beyond 40–50 km it often doesn't come at all.
Add the account in the app
- Open Settings → External GNSS / NTRIP and turn on App corrections.
- Tap NTRIP account, then Add account.
- Enter an Account name, the Caster host / IP, Caster port, Username and Password. Turn on TLS if your service supports it; without it the password is sent unencrypted.
- Leave Choose the base station automatically on. The app uses the service's network or automatic mountpoint if it has one, and otherwise the station nearest to you. To pick one yourself, turn it off and tap Load mountpoints.
- Go back and tap Connect, or Reconnect with updated settings if the receiver is already connected.
You can save several accounts and switch between them. While a measurement is open, the account in use stays until it ends, so one measurement never mixes two services.
On Android everything is on one panel: open Settings → External GNSS / NTRIP, turn on App NTRIP corrections, tap Add account, and fill in the fields that appear below the account list. Then tap Connect / apply. The panel's NTRIP line shows whether corrections are arriving.
Check that corrections arrive
Under NTRIP on the receiver page:
- Receiving corrections, with Received from caster and Sent to receiver counting up.
- Receiver: Using corrections · age 1.0 s means the receiver is applying them. Received, not used by the receiver means they reach the receiver but it ignores them: enable its RTCM input on this connection.
- Base station shows the station in use and how far away it is.
The app only chooses mountpoints that send RTCM 3, which almost every RTK receiver decodes. If a mountpoint sends no satellite observations, the app says so; choose another.
One service per job
Correction services publish positions in their own reference frames. In North America, for example, a service using NAD83(2011) and one using ITRF2020 can disagree by about a meter, while each reports centimeter accuracy. The app keeps each measurement on one correction source. For repeat work on the same site, stay with the same service.
Not getting a fix? See Why isn't RTK fixing?