Built-in DSC watch function monitors Ch 70 (DSC channel) activity, even while you are on another channel. In an emergency situation, a formatted distress call can be sent at the touch of a button.DSC uses a unique ID (MMSI code), allowing you to make contact with a specific boater or group of boaters in your area. A total of 100 address IDs can be stored with a 5-character name.With an external GPS receiver, the position request and position report functions allow you to exchange ships position. The received position information can be plotted on a third party GPS or other navigation equipment which accepts NMEA data format. The polling (request/reply) function checks whether a specific ship is in the communication range.Use the hand microphone as part of a public address system and make an announcement on-board or to shore through an external loud speaker or hailer. The RX speaker function allows you to monitor the received audio from the loud speaker or hailer while you are on the deck or tower.