How to use GPS as an external clock ?

External GPS antenna can be used to replace the internal clock of the SDR card (that has a frequency accuracy of 2ppm).

To move to external GPS antenna clock:

service lte stop

./sdr_util gps_state

Repeat this command until gps is locked . The GPS takes a few minutes to synchronize

Device /dev/sdr0

GPS locked TAI: 2019-10-08 09:52:31 UTC: 2019-10-08 09:51:54

* Once GPS is locked, modify the rf configuration file for using it : As instance in /root/enb/config/rf_driver/config.cfg uncomment the line

// sync: "gps", --> sync: "gps",

* start lte service:

service lte start