In order to utilize a Trimble GFX-series display, you have to connect either a NAV-500 or a NAV-900 GNSS controller. The differences between the two concern positioning accuracy and steering-system compatibility.
Install on the vehicle roof like any other receiver/globe. And yes, this is where GPS, GLONASS, and other positioning signals are processed into real-time coordinates for guidance and product application. But, the unit also includes accelerometers to offer roll-corrected data for steering tasks and third-party devices.
The NAV-500 should be used if only SBAS (WAAS) is required for positioning accuracy. The NAV-500 can be licensed for EZ-Steer, EZ-Pilot, and EZ-Pilot Pro steering systems.
With the proper license, the NAV-900 has access to several positioning services for various accuracy ranges. Steering licenses for the NAV-900 include every legacy electric or hydraulic Trimble steering option, and a CAN-based “steer by wire” option for compatible vehicles. If you currently have a hydraulic-steering option that uses a NavController III steering controller, then that can be incorporated with the NAV-900. If you require RTK by radio, a standalone radio receiver can be paired with the NAV-900.