How to check if Raspberry Pi is receiving NTRIP correction signals

Q&A forumCategory: QuestionsHow to check if Raspberry Pi is receiving NTRIP correction signals
carloskantorl asked 2 months ago
Hi, 
We have a rover connected to the simpleRTK + 4g Ntrip client running in a raspberry with ubuntu. We tested the hardware in a computer with u-center and the corrections are arriving. But when I test the program in the rover it feels that the position is not being corrected. Is there any way to check if the fix is happening? For example using the cgps command?
Thanks in advance
Carlos
Ardusimple
Staff replied 2 months ago

Hi Carlos,
Careful that raspberry pi is not driving the pins that you are using to communicate the 4g ntrip with simpleRTK2B. If you use UART1 with raspberry pi, use UART2 for 4G NTRIP and check that RPi I/O are not driving the pins of UART2.

carloskantorl
replied 2 months ago

I am connecting via USB (ttyACM0). I am able to get the raw data, and to connect to the socket and see the position in the cgps monitor.
THe switch is in UART1. Also when I connect it to the computer.
So with the computer it should be in UART1 and with the raspberry in UART2? And I don’t need to use two cables right? Will run and tell what happens.

Ardusimple
Staff replied 2 months ago

Sorry then, I assumed you were using the UART adapter. Then the suggestion above is not the problem.

In your case then, the usual problem is using a linux library that changes the configuration of the gps (e.g. changes uart baudrate or messages enabled) and then it stops communication with 4G device. Is this possible in your case?

carloskantorl
replied 2 months ago

It could be, I can select the baudrate of the communication (RPi-SimpleRTK) so that won’t be a problem. But I don’t know how to check if those messages are enabled.
So the connection is not only one way? I am searching a command to get the same info as when I am connected to the pc and you can search for UBX-MON-MSGPP. Should I see in the raw input if this message comes? or it is already used for correcting the incoming signals?

Ardusimple
Staff replied 2 months ago

Yes in UBX-MON-MSGPP you should see the RTCM messages coming in from the 4G.

clive1
replied 2 months ago

UBX-RXM-RTCM also reports reception of RTCM3 messages, looking for MSM4 or MSM7 type observations rather than “corrections”