To determine if a GPS fix is obtained, could use either of these SCPI query commands:
- :GNSS:REF? query returning a “GNSS” response, or
- :STATus:QUEStionable:CONDition? returning a value that contains the bit position 9 with a ‘1’ (or 512) could be used as a detection method.
See also this FAQ article: Why my GPS location data doesn't look right?