Garmin GPSMAP 495 - Manual (Page 161)

GPSMAP 495 Owner’s Manual 153
Appendix > Digital Selective Calling (DSC)
Digital Selective Calling (DSC)
Digital Selective Calling (DSC) uses marine VHF radio and Global
Positioning System (GPS) technologies to transmit and receive
location information. DSC is used by mariners to assist them in two
major areas: Distress Calls and Position Reporting.
A non-emergency DSC Position Report allows mariners to exchange
and show the locations of one another. When you receive a DSC
location, you can create a waypoint or to show the received location
on an electronic map.
An emergency DSC Distress Call allows a vessel in trouble to
transmit a substantial amount of information in a single transmission
or “call,” without the need for voice communication. When any
nearby rescuer receives the DSC signal, an alarm sounds and they
immediately receive the location of the caller.
The rescuer can choose to navigate (Go To) the caller’s location to
assist or forward the call on to the Coast Guard. When the Coast
Guard receives the call, they can immediately access the caller’s
information (such as who they are and the type of vessel) in their
database while they are in transit to the caller’s location.
Any time a vessel receives a DSC call, they can store that location
and quickly navigate to that location using a Go To. This makes
DSC a time-saver, especially in an emergency situation. In order to
use DSC, users must first register their VHF radio with the FCC and
receive a Maritime Mobile Service Identity (MMSI) number.
What is a Maritime Mobile Service Identity
(MMSI)?
Maritime Mobile Service Identity (MMSI) basically allows a VHF
radio to act like a phone. The 9-digit MMSI number acts like a
phone number when used in a Position Report and as a unique
identifier to the Coast Guard when used in an emergency Distress
Call. To obtain a Maritime Mobile Service Identity (MMSI) number,
users must register their VHF radio with the FCC (Form 605).
Garmin does not supply this number!
For more information regarding MMSI’s visit
www.navcen.uscg.gov/marcomms/gmdss/mmsi.htm .