I did this back in the day using a ublox LEA-M8F module for my PhD work following the instructions posted here: http://www.opendigitalradio.org/lea-m8f-gpsdo ht

I did this back in the day using a ublox LEA-M8F module for my PhD work following the instructions posted here: http://www.opendigitalradio.org/lea-m8f-gpsdo http://www.opendigitalradio.org/lea-m8f-gpsdo I also experimented with RTK which this module is capable of. Now there's probably a more up to date ublox module available which could provide even better results using multi frequency GNSS etc.