Change NMEA data format


#1

I am working with SW Snapdragon X7 LTE/GNSS module for both GSM and Positioning. However i found out, that the modules NMEA string is deliverd in ANSI dataformat.
The NMEA specification is telling to deliver messages in ASCII data format. However, I do have some applications which cannot deal with the ANSI format, so i wanted to ask, if there is a way to change that by any AT command on the module?

This is a screenshot with the modules NMEA Data displayed in ASCII


#2

@bbretschneider,

So which module are you using? All of our units just output standard NMEA sentence? There isn’t really a way to change this other than to select the sentences that are output, what do you want to do?

Regards

Matt


#3

@mlw thanks for the reply,
I am using Sierra Wireless MC7455 module. So basically we do have a application which works with serial GPS to log data from sensors.
The application is working propperly for more then 15 years with various suppliers for GPS receivers and is under continuos development. I wanted to change the GPS receiver from ublox to sierra wireless since i was not really happy with ublox’ costumer support, but i am facing difficulties with the MC7455 and our software. Basically, I cannot see any GPS-Data beeing received from our Software via the serial Interface.

I started investigation and tested the following:

  • changed NMEA start from “when COM opens” to “on module start” > no difference
  • changed NMEA output sentences to the only required GGA, VTG and RMC > no difference
  • checked the output format > difference to previous working ublox modules

So i compared the output format from MC7455 to the ublox modules and found out, that displaying the messages in ASCII is showing the weird formating, changing displaying in ANSI and everything looks ok.
ALso interessting: Trying to open the serial NMEA interface with ublox software u-center is showing continuously connect and reconnect on the interface, which is also a strange behaviour. I expect the software to be at least able to propperly open standardized NMEA COM-port, it should not be any problem weather it is a ublox or sierra module.

I really dont know what else could be the problem. I hope one of you guys have seen similar. I would really like to stick to this module.


#4

@bbretschneider,

I just need to confirm what you mean because the MC74 from a hardware point of view does not support a serial interface. It only supports different serial ports over the USB, so in a Linux based system this would equate to /dev/ttyUSB1 (the NMEA port). Is this what you are monitoring and failing to see the NMEA sentences come out of?

Regards

Matt