RTK Vertical (Altitude) Data Issues on Android Apps
Quote from anonymous on December 30, 2025, 10:54 amBelow is the question from one of our customer:
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Good morning,
Last October I purchased a Bynav X8-M1 GPS receiver from you. I use it for my work and I am very satisfied with it—thank you very much!
I use the X8-M1 connected to my smartphone via Bluetooth with the ByCenter app, and the RTK correction from my CORS provider works well.
For my surveys I use the QFIELD or SW Maps app with mock position. QFIELD correctly receives the horizontal XY data with RTK fix, but it does not receive the corrected vertical Z (elevation) data.
Let me explain: the vertical elevation value and the accuracy that I see in ByCenter are not the same as what I see in the QFIELD app, unlike the horizontal data, which is correct.
Is there a solution?
Do you know of another GIS smartphone app that solves this problem?
Thank you and Happy New Year.
From Italy
Below is the question from one of our customer:
==============
Good morning,
Last October I purchased a Bynav X8-M1 GPS receiver from you. I use it for my work and I am very satisfied with it—thank you very much!
I use the X8-M1 connected to my smartphone via Bluetooth with the ByCenter app, and the RTK correction from my CORS provider works well.
For my surveys I use the QFIELD or SW Maps app with mock position. QFIELD correctly receives the horizontal XY data with RTK fix, but it does not receive the corrected vertical Z (elevation) data.
Let me explain: the vertical elevation value and the accuracy that I see in ByCenter are not the same as what I see in the QFIELD app, unlike the horizontal data, which is correct.
Is there a solution?
Do you know of another GIS smartphone app that solves this problem?
Thank you and Happy New Year.
From Italy
Quote from GeoAstra Official on December 30, 2025, 10:55 amHi Lorenzo,
Happy new year! Thank you for the detailed explanation — that was very helpful.Based on your description and the fact that ByCenter shows correct RTK FIX vertical values, we can confirm that the X8-M1 hardware, RTK corrections, and CORS service are all working properly. This indicates that the issue is not related to the GNSS receiver itself.What’s happening is most likely related to how Android handles “Mock Location”, combined with how QField processes vertical (Z) data. On Android, Mock Location is primarily designed for testing and navigation purposes, and while it works well for horizontal positioning (XY), vertical elevation (Z) data is often not passed through reliably. As a result, many GIS apps may display altered or uncorrected elevation values even when RTK is active.
Recommended solution
You have a couple of good alternatives:
1. Use an app with a built-in NTRIP client, such as SW Maps.
These apps can connect directly to both the external GNSS receiver (X8-M1) and the CORS/NTRIP service within the same app, avoiding Android Mock Location altogether. In practice, this often results in correct RTK vertical readings.2. Use ByCenter for accurate Z values.
Since ByCenter reads GNSS data directly from the receiver, it will always display the correct RTK vertical elevation and accuracy, and can be used as a reference when precise Z values are required.Best regards,
Support Team
CanadaGPS
Hi Lorenzo,
What’s happening is most likely related to how Android handles “Mock Location”, combined with how QField processes vertical (Z) data. On Android, Mock Location is primarily designed for testing and navigation purposes, and while it works well for horizontal positioning (XY), vertical elevation (Z) data is often not passed through reliably. As a result, many GIS apps may display altered or uncorrected elevation values even when RTK is active.
Recommended solution
You have a couple of good alternatives:
These apps can connect directly to both the external GNSS receiver (X8-M1) and the CORS/NTRIP service within the same app, avoiding Android Mock Location altogether. In practice, this often results in correct RTK vertical readings.
Since ByCenter reads GNSS data directly from the receiver, it will always display the correct RTK vertical elevation and accuracy, and can be used as a reference when precise Z values are required.
Best regards,
Support Team
CanadaGPS