The wonderful world of the DSC

by Ron Trossbach/Sail-World Cruising on 23 Mar 2009 Do you have a DSC facility on your radio? If you are asking 'What is a DSC?' then you really need to study this article.

Are you confident that you know ALL the side benefits of this technology? If not, then there is much of value to read below.

Digital Selective Calling (DSC) distress alerts, which consist of a preformatted distress message, are used to initiate emergency communications with ships and rescue coordination centers. Most marine radios now have a DSC facility, consisting of a simple button, which can be pushed in the case of an emergency.

It is the least expensive and the most significant safety improvement that writer Ross Trossbach has seen in over fifty years. Later in the article are the full details for leisure craft on the uses of DSC, but the potential use goes much beyond the uses strictly for emergencies, to other communication advantages, summarised here by Ross:

1.  The ability to call ships on the high seas using their MMSI obtained from AIS
2.  The ability to request the position of any unit having an MMSI. 
3.  The ability to call an individual station and automatically switch him to a working channel
4.  The ability to call a group of stations and automatically switch them to a working channel
5.  All positions received can automatically be displayed on most Navigation plotters
6.  An entirely new Man Overboard alarm and real time position reporting system (VPIRB) uses DSC too.
    

These are all extra facilities, and all you need is a little time and practise. The additional advantage of these facilities is to keep Channel 16 as free as possible. This is vital to safety, and all users of marine radios, even in those countries which have been deregulated, are advised to undertake a radio course.

..............................................

Here below is the paper on the emergency aspects of DSC produced by the Cruising Club of America, and supplied by Ron Trossbach:

DIGITAL SELECTIVE CALLING
The use of Digital Selective Calling (DSC) in VHF and SSB radios is relatively new and not widely understood. This paper will give the reader a broad view of what DSC is and how it applies to recreational boats. Web site links and references are included for more detailed explanations.

DSC definitely has a place in small boat operations and is simple to install with potentially huge safety benefits. It is no longer necessary to read latitude and longitude numbers over the radio in emergencies or when exchanging position information with another boat. DSC does this automatically in less than one second. The best part is that DSC capability should already be in VHF and SSB radios built/sold in the US after June 17, 1999.

The physical hookup is relatively simple - two wires between any model radio and any model GPS. The registration is FREE, and details of how to do this vary from country to country.

'The Coast Guard urges, in the strongest terms possible, that you take the time to interconnect your GPS and DSC-equipped radios. Doing so may save your life in a distress situation!' See www.navcen.uscg.gov/marcomms/gmdss/dsc.htm

This site also provides the background, history and description of how DSC fits into the Global Marine Distress and Safety System (GMDSS).

A recent CCA publication titled Digital Selective Calling and Search & Rescue Areas has important details and information on Digital Selective Calling, MMSI, AIS and Search and Rescue areas in the Atlantic and Pacific. This is a comprehensive review of how to make the most of your DSC-capable VHF and SSB, and how to use the technology to maximize your chances for a successful rescue at sea. See http://www.cruisingclub.org/pdfs/dl.asp?fn=com_dsc_sar.pdf

Boat U.S. Foundation has an online tutorial on Marine VHF titled 'Can You Hear Me?' which is an interactive run-down of everything a boater wants to know about using a marine VHF radio with Digital Selective Calling (DSC). The headline on this announcement is 'Spending 35 Minutes Online Could Save Your Life'. See www.boatus.com/mmsi

At a bare minimum, responsible boaters should be capable of sending a DSC Distress Call as well as taking the correct action when a DSC alarm sounds on their radio. DSC is in place and operating now, especially in US coastal area where RESCUE 21 is operational. This is a huge safety improvement that all boaters should understand and be prepared to use in case of emergency.

MAKING A DSC DISTRESS/MAYDAY CALL.
This call is only made when personnel and/or property are in immediate danger and immediate assistance is requested. Press the Red Distress Button on your radio and hold it in for five seconds. Listen for a DSC Distress Acknowledgement. After it is received, or if it isn’t acknowledged, shift to the VHF Distress, Safety and Calling Frequency (VHF Ch-16) or a SSB Safety and Hailing Frequency (2182, 4125, 6215, 8291, 12290 or 16420 kHz, USB) and issue a voice MAYDAY, following the format on the Emergency Card on the reverse side of this paper. Persons in distress should use any frequency/means to alert other mariners/persons ashore to their plight.

IF YOU HEAR A DSC DISTRESS CALL.
Shut the radio alarm off by pressing any button on your radio. Write down the MMSI and position information showing on your radio display screen. Wait 3-5 minutes for an authority to answer the call. If no other station replies attempt to verbally relay the MMSI and position information to USCG or Bermuda Radio. Contact the station in distress if no one else does and go to their rescue, if you are able to do so.

IF YOU ACCIDENTALLY MAKE A DSC DISTRESS CALL. Shut the call off. Get on the VHF Distress, Safety and Calling Frequency (VHF Ch-16) or SSB Safety and Hailing Frequency (2182 kHz, USB) and make an all stations announcement to cancel the DSC Distress Call.

DSC DISTRESS COMMUNICATION FORM - WRITTEN INSTRUCTIONS FOR USE
Copy and place the form below on a wall close-by each permanently installed radio equipped with DSC
(Fill in Items 5, 6, 11 and 13 prior to getting underway.)

SPEAK SLOWLY – CLEARLY – CALMLY
1. Make certain your radio and GPS are turned on and the radio is on High Power.
2. Send DSC Distress Call – press Red Distress Button for 5 seconds. Wait for a DSC Distress Acknowledgement then shift to VHF Ch 16 or SSB 2182 kHz (USB) for voice instructions.
3. If no DSC Acknowledgement is received Select VHF Ch 16 or SSB 2182 kHz (USB)
4. Press microphone button and say: 'MAYDAY - MAYDAY - MAYDAY'
5. Say: 'This is (Your boat name, MMSI or Call Sign)'
6. Repeat once: 'MAYDAY (Your boat name)'
7. Tell where you are:
a. Latitude and longitude __________________________________________________
b. Navigation Aids or Landmarks nearby __________________________________
c. Direction and distance from a Landmark ________________________________
8. State the nature of your distress and the kind of assistance required:__________________________________
9. Give the number of people aboard and condition of any injured ______________
10. Estimate present seaworthiness of your boat. ________________________________
11. If time allows - Briefly describe your boat:
a. Type – (Sail or Power) _____________________
b. Length in feet- __________________________
c. Hull color- _______________________________
d. Trim color- ______________________________
e. Masts- ___________________________________
f. Other Identifying Info- _____________________________________________________
12. Say: 'I will be listening on Channel 16 or 2182 kHz Upper Sideband '
13. Say: 'This is (Your Boat Name, MMSI or Call Sign) OVER'
14. Release microphone button and Listen for an Answer.
15. Activate 406 MHz EPIRB by following directions on Beacon Body. Ensure EPIRB remains vertical, antenna pointing upward. Take EPIRB to Survival Craft if abandoning ship.
16. If you do not receive an answer Repeat Call beginning at Item 3.
17. If no answer again Check to see if radio is turned on and VHF is on CH 16, high power or shift SSB to 4125 kHz (USB) or higher emergency frequencies for communications with distant shore stations.