Which of the following is NOT an input of the Navigation Sensor System Interface (NAVSSI)?

The Navigation Sensor System Interface (NAVSSI) is designed to integrate various navigation sensors to provide a comprehensive view of a vessel's position and movements. In this context, the magnetic compass does not serve as a direct input to the NAVSSI. Instead, it is traditionally used as a standalone navigation aid for heading reference, but it does not provide the digital data interfaces required for integration with modern systems like the NAVSSI.

In contrast, the other sensors listed are considered primary navigation inputs for the NAVSSI. The GPS VME Receiver Card offers vital geographic positioning data, the fathometer contributes depth information critical for safe navigation, and the Doppler Sonar Velocity Log provides crucial velocity and drift information based on sonar measurements. These sensor technologies integrate well with the NAVSSI to support enhanced navigational capabilities, which is why they qualify as inputs for the system.