GNSS receiver configuration commands

config
    - card 1
        - mda 1
            - gnss
                - constellation {gps | gps-glonass}
                - nmea 
                    - sentence-types sentence-type [sentence-type...(up to 4 max)]
                    - sentence-interval interval
                    - [no] shutdown 
                - [no] shutdown 
                - [no] sync-system-time