RTK GNSS on iPhone and Android: MapLab Survey workflow with an external receiver
A phone becomes a serious field tool when corrected external RTK GNSS position is combined with the right project, CRS and field records.
Field takeaways
- External RTK receivers commonly send corrected NMEA position to the phone over Bluetooth.
- NTRIP/CORS corrections are usually configured on the receiver side.
- MapLab Survey connects corrected position to project, layers, notes, photos and export.
- Do not record critical points before fixed status and known-point checks.
- Antenna height and vertical reference must be documented.
The chain, not the phone
In RTK work the phone is not the measuring instrument. The chain is the external GNSS receiver, the antenna, the correction source, the Bluetooth/NMEA stream, the MapLab Survey project, the coordinate system and the control point — working together. If one link is missing, the measurement looks fine and fails at delivery. The centimetres come from the receiver, the correction stream and the check; the phone runs the software and stores the data.
Who does what
The receiver produces the position; an NTRIP correction service — in Türkiye, CORS networks such as TUSAGA-Aktif are the common source — removes most of the atmospheric and orbital error; the app turns the corrected position into field data. In most workflows the NTRIP details are configured on the receiver side, and MapLab Survey consumes the corrected stream.
What to check in the app
- Is the external receiver connection active?
- Is the solution fixed, float, DGPS or single?
- Does the antenna height match the actual pole height?
- Are the project coordinate system and EPSG right?
- Is the difference at a known control point inside tolerance?
Fixed is not a signature
A fixed solution is a good sign, not a guarantee. Recording a parcel corner, a stake-out point or a level without checking a control point is a risk. Measure a known point at the start of the day and again at the end — if it agrees within tolerance the chain is sound; if not, nothing measured in between is worth keeping. iOS and Android are equivalent here: both accept standard NMEA over Bluetooth, so the receiver and the correction source matter far more than the handset.
Export with the context attached
Charge the phone, check the receiver battery, test the NTRIP access and load the project and base map before leaving; if the link drops, stop taking critical points and note it. And when the work ends, do not send bare coordinates: share the fix status, antenna height, time, control note, source CRS and target EPSG with every KML/KMZ, DXF, GeoJSON or CSV. That context is what makes the office trust the file.
Try these steps on your own phone.
MapLab Survey handles RTK/GNSS point capture, drawing, area and volume calculations and coordinate conversion, then exports to DXF, KML/KMZ, GeoJSON, Shapefile, GeoPackage, NCZ or CSV. Capture, calculation and export work offline. Live NTRIP corrections and online basemaps need a connection.
Frequently asked questions
Does MapLab Survey work with RTK receivers?
It supports a workflow for using external receiver position in field projects.
Is fixed status enough?
No. Use known-point checks.
Why antenna height matters?
It directly affects height values.
Technical references
The field guidance in this article is aligned with the technical and official references below.
Related: RTK GNSS field accuracy · GNSS Z and elevation · Field survey checklist · MapLab Survey