How to Log GNSS Data Every 60 Seconds on RTK Postcard + Portability Shield

GPS/GNSS
1

Hi SparkFun team,

I’m using the RTK Postcard along with the Portability Shield. Currently, the system logs GNSS data to the SD card every second, which I believe is the default behavior. However, for my project, I only need to log data every 60 seconds to reduce file size and processing overhead.

Is there a way to configure this logging interval directly through the device’s config settings , rather than adding an Arduino? I’d prefer to stick with built-in options.

Thanks

2

Hi @Nima.m ,

You can reduce the size of the log files by only logging the messages you need. If you only need GGA for example, turning off RMC, GSV, GSA, VTG, GLL, GST will reduce the file size dramatically. Turning off GSV on its own will make a big difference.

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Unfortunately, the slowest “measurement rate” you can set in the RTK Everywhere firmware is 1Hz / 1 second. If you really need a logging interval of 60 seconds, you would need to write your own firmware.

It would be much easier to write some simple “decimation” code, which would quickly stream through the logged data file and strip out every 60th message. It would need a little thought as some of the NMEA Messages are multiples (multiple messages are generated and logged each navigation interval). But, if you only need e.g. NMEA GGA, stripping out every 60th message would be very straight forward.

You may find that RTKLIB already provides this feature. It has a lot of tricks like this, which I haven’t properly investigated.

I hope this helps,
Paul

2 Likes
3

Thank you very much @PaulZC for your response. I’m not professional in firmware development, so writing a custom firmware is probably too complex for me at this stage. I’ll start by reducing the number of NMEA messages and see if that helps keep the log files manageable.