What do you need to have linked to properly use DSC for distress alerts?

Using Digital Selective Calling (DSC) for distress alerts requires having a GPS system linked to the equipment. The connection to a GPS is crucial because it allows the DSC equipment to automatically transmit the vessel's position along with the distress alert. This capability ensures that rescue services can accurately locate the vessel in distress, significantly enhancing the chances of a timely response and successful rescue operation.

The GPS system provides real-time positional data, which is an essential component of the DSC distress message format. Without this linkage, the distress call would lack critical information about the vessel's location, which could delay response efforts and increase the risk to life and property at sea.

The other options, while they may contain useful information for maritime operations, do not serve the primary function of linking the vessel’s position to the DSC system for the purpose of sending distress alerts. Thus, having a GPS system linked to your DSC equipment is the only choice that correctly fulfills the requirement for effective distress communication.