Before you start
Requirements
SW Maps installed from Google Play (Android) or App Store (iOS)
A GNSS receiver paired via Bluetooth — Emlid, Ardusimple, u-blox or any NMEA-output device
NTRIP credentials: host, port, mountpoint, username and password
Mobile data or Wi-Fi on your phone or tablet
Open sky view for your receiver — at least 15° elevation mask
SW Maps is completely free
SW Maps has no paid tier, no ads and no feature restrictions. The built-in NTRIP client works with any correction service and any compatible GNSS receiver out of the box.
Step 1 — Connect your receiver
Pair your receiver via Bluetooth
Turn on your GNSS receiver and pair it with your phone via the Android or iOS Bluetooth settings before opening SW Maps. Complete the Bluetooth pairing first — SW Maps discovers already-paired devices.
Select the instrument in SW Maps
Open SW Maps and tap the antenna icon in the top bar, or open the left menu and select Bluetooth GNSS. You will see a list of paired Bluetooth devices.
Select your receiver from the list. If you use USB OTG instead of Bluetooth, select USB Serial GNSS from the menu.
Set antenna height and connect
Set the Instrument Height to the distance from the ground to the bottom of your receiver, in metres. SW Maps applies the antenna offset automatically based on the receiver model if it is in the instrument list.
Tap Connect. SW Maps begins streaming position data from the receiver. The status bar at the top shows the satellite count and current fix type.
Go outside before connecting
Your receiver needs clear sky to acquire satellites. You can connect to SW Maps indoors to test Bluetooth, but move outside with a clear sky view before opening the NTRIP client — corrections only work when the receiver has satellite lock.
Step 2 — Configure the NTRIP client
Open the NTRIP Client
Open the left navigation menu by tapping the SW Maps icon in the top-left, then select NTRIP Client.
If NTRIP Client does not appear in the menu, your receiver is not yet connected. The NTRIP option only shows when SW Maps has an active instrument connection. Go back and connect your receiver first.
Enter your NTRIP credentials
Fill in the following fields:
Addressntrip.your-service.comPort2101Usernameyour-usernamePasswordyour-passwordMount PointRTCM3_NLTap the refresh icon next to the Mount Point field to load the sourcetable from the server. This downloads the list of available mountpoints so you can select the correct one for your location and device.
Enable GGA if using VRS
If your chosen mountpoint is a VRS (Virtual Reference Station) stream, enable Send NMEA GGA to NTRIP Caster. This sends your approximate position to the server so it can generate a local correction stream near you.
If you use a standard, non-VRS mountpoint, GGA is optional but does not cause problems if left enabled.
Tap Connect
Tap Connect. If everything is correct, the data stream counter begins incrementing — this confirms corrections are flowing from the server to your receiver. The NTRIP status button in the top bar turns green when connected.
Step 3 — Verify RTK Fix
Watch the position bubble on the SW Maps screen. It changes colour as your fix improves:
Blue — Single
No corrections.
Orange — RTK Float
Corrections received, but ambiguities are not yet resolved.
Green — RTK Fixed
Centimetre-level accuracy.
In a good environment with a nearby reference station, the bubble should turn green within 10–60 seconds of connecting to NTRIP. Once green, your position accuracy is at centimetre level.
To confirm, open the left menu and tap GNSS Status. You will see the fix type, estimated accuracy, number of satellites and PDOP. RTK Fixed with H accuracy below 0.03 m (3 cm) is a good result.
Green bubble = centimetre accuracy
Once SW Maps shows a green position bubble and your GNSS Status shows RTK Fixed, you are ready to collect or stake out points. Do not collect data while on Float — the accuracy is sub-metre, not centimetre.
NTRIP credentials reference
For RTKsub, use these values in the SW Maps NTRIP client:
Troubleshooting
| Problem | Likely cause | Fix |
|---|---|---|
| NTRIP Client not in menu | No receiver connected | Connect a GNSS receiver first via Bluetooth GNSS or USB Serial GNSS. The NTRIP option only appears with an active instrument connection. |
| Cannot connect to server | No internet, wrong host or port blocked | Check mobile data is active. Verify host and port. Switch from Wi-Fi to mobile data if on a corporate network. |
| Sourcetable empty or fails to load | Wrong credentials or server unreachable | Verify username and password. Try copy-pasting from your account dashboard rather than typing. |
| Connected but bubble stays blue | Corrections are not reaching the receiver, or receiver is indoors | Move outside. Check the data stream counter is incrementing. If it shows 0 bytes, GGA may be needed or the mountpoint may be wrong. |
| Stuck on orange (Float) | Long baseline, obstructions or weak signal | Switch to a VRS mountpoint. Move to open sky. Wait longer — Float can take several minutes in difficult conditions. |
| Green bubble but wrong coordinates | Datum mismatch in project settings | Check your SW Maps project coordinate system. SW Maps outputs WGS84 by default (EPSG:4326). For Netherlands, apply the RD New transformation in your export settings. |
| Fix drops after a few minutes | Unstable internet connection | Use a dedicated mobile hotspot rather than tethering through another app. Enable auto-reconnect in SW Maps NTRIP settings if available. |
Saving NTRIP profiles
SW Maps supports multiple saved NTRIP profiles. After your first successful connection, your credentials are saved. You can add additional profiles for different services or mountpoints and switch between them from the NTRIP Client screen.
