Field GNSS RTK Setup: USB Serial, NTRIP and FIXED Data Collection
Verified setup
- App version
- 2.7
- Android
- Android 15/16
- Receivers
- SCOUT PRO / SCOUT
- Last verified
On this page
App guides
App guides
NTRIP Inside
Field GNSS 2.7 reads the tested Kalmix SCOUT PRO / SCOUT as USB Serial devices and runs its own NTRIP client, so no bridge app is required for this Android workflow.
This guide records the USB Serial path. Field GNSS public material principally describes Bluetooth use; this article does not claim an Internal GNSS or disconnect fallback that was not independently verified.
What Field GNSS does with an external receiver
Field GNSS is an Android app for GNSS surveying and GIS data collection. It can use an external receiver over USB or Bluetooth, or the device’s Internal GNSS; it records points, polylines, and polygons with attributes on a map.
For this guide, SCOUT PRO / SCOUT supplies the position and Field GNSS returns NTRIP corrections over the same USB-C connection. The receiver calculates the RTK solution; Field GNSS reports that result. Internal GNSS is a different path and is outside this test.
Field GNSS is available from Google Play. Its documented capabilities include project and layer management, geotagged photos, coordinate systems, and DXF, KML/KMZ, and GeoJSON exchange. This article covers only the tested USB Serial and NTRIP path. For a different direct Android workflow, see the GNSS Master setup guide.
Before you start
What you need
- A Kalmix SCOUT PRO / SCOUT receiver. This verification used the default USB Serial output: standard NMEA 0183 at 115200 bps and 1 Hz.
- An Android phone or tablet with USB-C data transfer and USB OTG support.
- Field GNSS 2.7 and an NTRIP account: address, port, mount point, username, and password.
- An outdoor location with a clear view of the sky.
Connect SCOUT to Field GNSS over USB serial
-
01
Install Field GNSS and allow USB access
Install Field GNSS, connect the receiver’s USB-C cable, then tap OK when Android asks whether the app may access the USB device. The device powers SCOUT PRO / SCOUT and carries its GNSS output; no separate adapter is used in this setup.
Install Field GNSS, then connect SCOUT. 
Allow Field GNSS to access the USB device. USB port and battery
Only one app can hold the USB serial port. Close another GNSS app before connecting, and check the Android device’s battery before a long session.
-
02
Open the app and complete its prompts
Launch Field GNSS and complete the permissions it requests. Keep SCOUT in an open location while it starts tracking satellites.
The Field GNSS home screen. 
Complete the on-screen prompts. -
03
Open GNSS Settings
Tap the three-line menu at the top right, then select GNSS Settings. This is where you set both the receiver and correction links.
Open the top-right menu. 
Select GNSS Settings. -
04
Select the USB receiver
Open the USB RTK tab. Under GNSS Receiver, tap Select and set Baud Rate to 115200 and Device to the USB Serial entry. Then tap OK. The verified SCOUT PRO / SCOUT setup uses standard NMEA 0183 at 115200 bps, so no vendor-specific profile is required.
Open USB RTK, then tap Select. 
Set 115200 and USB Serial. -
05
Add the NTRIP caster profile
On USB RTK, tap Select under NTRIP Caster, then choose Add New NTRIP. Enter a name plus the address, port, mount point, username, and password supplied by your correction service or base station. Tap SAVE.
Tap Select under NTRIP Caster. 
Enter the correction-service details. -
06
Select the profile and connect
Select the saved profile in the NTRIP List, return to GNSS Settings, and tap Connect. Confirm that both GNSS Receiver and NTRIP Caster show their selected values. For repeat use, enable Connect when app opens.
Select the saved NTRIP profile. 
Both settings must be filled in. 
Receiver and NTRIP are connected. -
07
Confirm the solution status
Return to the home screen and watch its status label. FLOAT and FIXED are RTK solution states; wait for FIXED when your required accuracy and field procedure call for it. The status can change as sky view or corrections change.
GPS: standalone positioning. 
DGNSS: a differential correction is applied. 
FLOAT: ambiguities remain unresolved. 
FIXED: the target state for high-accuracy work. Use the map icon to switch to SATELLITE when imagery helps you check the feature against the ground.
Switch the basemap from the map icon. -
08
Inspect STATUS, sky view, and signal strength
Open the top-right menu and select STATUS. The PROJECT, GNSS, SKY VIEW, and SIGNAL STRENGTH tabs give the live evidence behind the status label. Use sky view and signal strength first when a solution will not hold.
STATUS opens the detailed report. 
Satellite geometry and signal strength. -
09
Collect GIS features
Use the lower-left tools to collect a Point, Polyline, or Polygon. Recheck the status before each feature; FIXED is the conservative collection gate for high-accuracy work, but your project’s accuracy procedure remains the final authority.
Point: record one position. 
Polyline: record a connected line. 
Polygon: record a closed area.
Read the Field GNSS solution status
The setup is ready for RTK work when the receiver and NTRIP caster are connected and the home screen reports FLOAT or FIXED. The table below defines the status labels; they describe the current solution, not a guarantee of a measurement result.
| Status | What it means |
|---|---|
| GPS | Standalone GNSS positioning. No correction data is in use. |
| DGNSS | A differential correction is in use, but the receiver has not produced a carrier-phase solution. |
| FLOAT | A carrier-phase RTK solution with unresolved integer ambiguities. |
| FIXED | A fixed carrier-phase RTK solution and the target state for high-accuracy work. |
Field GNSS USB, NTRIP and FIXED troubleshooting
Use the table below to isolate the failed link before changing another setting: USB Serial device, receiver output, NTRIP session, or RTK solution state.
| Problem | What to check |
|---|---|
| No USB Serial device | Reconnect the receiver, accept the Android USB prompt, verify USB OTG/data support, and close any other app that may hold the port. |
| Connected but no position | Set 115200 and USB Serial, then move to a clearer sky view. |
| Status remains GPS | Verify that the selected NTRIP profile connects and that the Android device has usable internet. |
| NTRIP connects but remains DGNSS | Check mount point, credentials, regional coverage, and baseline. Then inspect SKY VIEW and SIGNAL STRENGTH. |
| FLOAT will not become FIXED | Look for obstructed sky, a stalled correction stream, or an unsuitable baseline; move to open sky and recheck. |
| Link drops after switching apps | Return to Field GNSS and reconnect. Enable Connect when app opens and review Android background and battery restrictions. |
Frequently Asked Questions
Should I wait for FIXED before recording a point in Field GNSS?
For high-accuracy collection, use FIXED as the conservative gate and recheck it before each feature. FLOAT is an RTK solution, but the project accuracy procedure remains the final authority.
Can Field GNSS reconnect to the receiver automatically?
Enable Connect when app opens in GNSS Settings, then confirm that both the receiver and selected NTRIP profile reconnect before collecting data.
Which Field GNSS screen shows why a solution will not hold?
Open STATUS and inspect SKY VIEW and SIGNAL STRENGTH first. They show the satellite geometry and signal evidence behind the home-screen solution label.
Does Field GNSS fall back to Internal GNSS when the receiver disconnects?
This guide did not independently verify the disconnect fallback. If the receiver connection changes during collection, stop and confirm the source and solution status before recording another feature.
Receiver used in this test
SCOUT PRO and SCOUT completed the verified Field GNSS 2.7 USB Serial setup in this guide. Both use the USB-C host interface and default NMEA output recorded here.
Kalmix SCOUT
A compact dual-band RTK G-Mouse for evaluation, prototyping, education, and open-sky deployments.
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Kalmix SCOUT PRO
A field-ready dual-band RTK receiver for robotics, AGV, precision agriculture, and construction machinery.
View SCOUT PRO →Need help with a different Android workflow? Contact Kalmix support →