What is a characteristic of 406 MHz EPIRB transmissions?

The transmission of 406 MHz Emergency Position Indicating Radio Beacons (EPIRBs) is characterized by the use of a unique hexadecimal identification number. This identification number is crucial for search and rescue operations, as it allows authorities to determine the specific EPIRB's registration details, which include the owner and any associated vessel information. This unique coding is essential in distinguishing between different EPIRBs, ensuring that the proper response is initiated when a distress signal is received.

The identification number, transmitted as part of the EPIRB's digital message, enhances the efficiency of rescue operations by providing responders with immediate information about the distress signal's origin. This systematic approach significantly improves the chances of successful rescues.

In contrast to the correct option, the other choices do not describe the characteristics of 406 MHz EPIRB transmissions accurately. For instance, these beacons utilize digital signals rather than analog, they do not transmit voice messages but send distress information in a digital format, and they operate primarily on the specific frequency of 406 MHz without simultaneous multiple frequency usage.