Wrong accuracy value in android

Q&A forumCategory: QuestionsWrong accuracy value in android
Andrea Barcaro asked 1 month ago

I’m using simpleRTK2B connected via bluetooth to an Android device with the app Lefebure NTRIP Client. I got the connection and I mock the location but I can’t get the correct accuracy value.
Connecting simpleRTK2B with USB to a PC I get displayed the actual accuracy (in the u-center software). At the same time in Android is always displayed the max range accuracy (in this case in Android isn’t displayed 0.06m, but is displayed 0.5m). How can I display in Android the correct accuracy? I developed an Android app to see if other apps were the problem, but nothing to do: I get the same results (I got displayed 0.5m or 0.2m for example but never values between them).
Thank you for your attention.

4 Answers
amorosik answered 1 month ago

What bluetooth interface was used?
How is it read on an android device?
Is it possible to see the little test program, on an Android system, that reads the values?
Have you tried to log raw data, as read from interface bt and compare them with data as read on U-center view / text-console?
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Barcaz01 replied 1 month ago

I used XBlee bluetooth module from ardusimple and I paired it via Bluetooth with my android phone. The test program just shows values as other apps that shows accuracy/error so at the moment it’s useless.
Now I just uploaded what u-blox center was showing in my PC 🙂

clive1 answered 1 month ago

Where are you pulling these values from? The DOP numbers aren’t in metre units.

Barcaz01 answered 1 month ago

This is what I get in ublox center with PC. In Android as accuracy I don’t get 0.06m but I get 0.50m

clive1 replied 1 month ago

So is the Android in the same RTK-FIXED mode? Reporting UBX-NAV-PVT ?

Barcaz01 replied 1 month ago

Yes in Android there is the same RTK-FIXED mode because I use NTRIP client app in Android and at the same time I display results in PC.
I don’t know about UBX-NAV-PVT, I enabled it to display these results in the PC because nothing was showing in “3D Acc.” or “2D Acc.” row. Should I set something for the Xblee Bluetooth connection? Maybe I have to connect the micro USB in the opposite board side of the antenna side and try to enable this UBX-NAV-PVT also there?
Thank you for your attention

clive1 replied 1 month ago

I don’t know the requirements/expectations of you Android application. The UBX-NAV-PVT message imparts the hAcc and vAcc parameters uCenter is displaying, a couple of others may also provide these. The application doesn’t automatically enable messages, but pulls data from those messages which are, normally the NMEA ones. If the receiver doesn’t provide the data, uCenter doesn’t update the fields.
The UBX commands and packet content are described in the Interface Description (prior devices used the Protocol Specification)

paulo answered 3 weeks ago

I’m using the same setup, and get the “correct” accuracy displayed when in the display settings i select for one of the boxes  3D RMS (from GST/LLQ). The Lefebure App polls NMEA messages via UART2 / bluetooth from the simple RTK2B board.
The larger values mentioned come from the DOP information, not from accuracy.
Most of the standard Apps I tested using the mock gps are not able to use the high precision data from the board.

Barcaz01 replied 3 weeks ago

The values that “3D RMS (from GST/LLQ)” from Lefebure App isn’t exatly the same as is displayed in 2D error in u-center.
But the real issue is that this valued isn’t mocked. I’d like to get monitored in another app that I’m creating what’s the actual error reported in meters