GPSD stands for GPS Daemon. It allows the DataHub Pro to share the GPS position it is receiving with other compatible devices or navigation software on your local network.
For example, the DataHub Pro may be receiving GPS position from its own GPS antenna or from your boat’s NMEA 2000 network. When GPSD is enabled, software on a connected laptop or other device that supports the GPSD protocol can use that position information directly from the DataHub Pro.
You would normally only need to turn GPSD on if the navigation software or device you are using specifically supports or asks for a GPSD connection.
It is not required for normal PredictWind GPS Tracking, as the DataHub Pro can already use its available GPS source for tracking and other PredictWind features.
If your navigation software instead uses NMEA 0183 over TCP or UDP, you would generally use the DataHub’s NMEA networking options rather than GPSD.
So in short, GPSD is an optional way of sharing the DataHub Pro’s GPS position with compatible third-party software. If your software does not specifically require GPSD, it is fine to leave it turned off.