DSC levels and functions

[DMCI]

If you send out an automated distress call with the red button on your vhf radio, it only sends a distress call, but no position information. By interconnecting a GPS unit to the radio, it will also send you currrent position information as well:

Classes of Digital Selective Calling
The DSC protocol is defined by ITU-R Recommendation M.493 (series), available from the International Telecommunications Union in Geneva, Switzerland DSC operation is defined by ITU-R Recommendation M.541 (series).



Class A:
Distress call
All-ships call
Individual station call
Semi-automatic/automatic service call
Use of distress, urgency, safety and routine priorities
Nature of distress
Distress coordinates
Time for last (distress) position update
Type of subsequent communications
Distress relay
Distress acknowledgment
Test call (for MF/HF only)
Radio frequency or channel
Display
Receive geographical area calls
Alarm
Optional means for canceling a distress alert
Polling
Position acknowledgement
Test call
Test acknowledgement
Data
Data acknowledgement
All DSC options provided. Required on MF/HF and VHF radios used by SOLAS-regulated ships. Class A includes polling and vessel tracking, data, and numerous other functions in addition to voice.
Class B:
Required on VHF and MF radios used by SOLAS-regulated ships, though most such radios in fact meet Class A. Class B required capabilities include:

Distress call
All-ships call
Individual station call
Semi-automatic/automatic service call
Use of distress, urgency, safety and routine priorities
Nature of distress
Distress coordinates
Time for last (distress) position update
Type of subsequent communications
Distress relay
Distress acknowledgment
Test call (for MF/HF only)
Radio frequency or channel
Display
Receive geographical area calls
Alarm
Optional means for canceling a distress alert
Back to Classes


Class D:
Minimum DSC capability for VHF marine radios carried by recreational boaters, commercial fishing vessels, and other non-SOLAS regulated vessels. Class D required capabilities include:

Distress call
All-ships call
Individual station call
Use of distress, urgency, safety and routine priorities
Nature of distress
Distress coordinates
Time for last (distress) position update
Type of subsequent communications
Radio VHF channel
Display
Receive distress relay and distress acknowledgment calls
Alarm
Distress acknowledgement (receive)
Geographical area call (receive)
Test call
Test acknowledgement




The above radio when connected to GPS will also display your lat/lon and transmit this with your automated distress call, a nice feature when you are busy repairing your bilge pump.

[Tim_Mattson]

Good info Dave,
I was down at Wooldridge Boats and had them tell me of a customer who was returning from a trip offshore at Neah Bay like he`d done for 20 + years.Coming off a following wave they plowed into the backside of another wave and had the front windows blow out as they scooped a bunch of green water over the bow.
Another wave then hit them from the rear corner and they had time to reach for two PFDs and depress the distress button on the Vhf radio, as the boat SANK out from under them in seconds.
Luckily another boat with a buddy decided to come in shortly after and happened upon the scene.A larger cooler and the pfds kept them afloat and luckily the Coast Guard didn`t have to use the locating system......boat was
120` down so they would have only the last known postion to go from......
Once brimmed ,you rarely get a 2 nd chance so these distress features do give you ability to get help from shore.
It didn`t hit the guy until a day or two later when he looked at the weather map and where they were....10 miles out ,halfway back from the "Blu Dots".
TM

[Guest]

And a couple years ago, when I lived in Los Angeles, I read about some guys who had engine trouble off the Oregon coast and were drifting into the surf. One of them radioed the Coast Guard, and the conversation went something like this:

Where are you?

I don't know.

Do you have GPS?

The guy who knows about that is below trying to start the engine.

If I recall correctly, there were four people on board and one survived. Every time I take a new person on my boat I explain that the GPS and radio always on from the time we leave the dock until we get back- if you see if off, tell me immediately. And I explain about the red button and how to use it. I just learned you can now buy VHF radios with GPS built in, which makes excellent sense. I'm restoring a 1950's midget cruiser, so I'm boatless for a few more months, but that's on my list of must-haves.

[DMCI]

Gentlemen:

Thankyou for the kind replys and further insights.

I am using ICOM only as a technical example here as they do a nice job of integration.

Here is an example of a GPS by ICOM that will provide position to the VHF for retransmission. It's main virtue is relatively low cost. It plots relative position to other vessels only, but limited geographical data.

[Helmar]

Automatic Identification System

Here is the link I did on the AIS radio that was coming out some time ago.
Hope the link works.

[ame="http://www.classicboatclub.com/forums/showthread.php?t=3291"]AIS, Poor mans Radar & VHF Radio - Northwest Classic Boat Club Forum[/ame]

[DMCI]

Helmar:

Very nice work. I think communications is something that the Sr Members should encourage, as an enhancement of your very nice saftey oriented philosophy.



The above unit is the one that I might very well install on the moppie and my 17 Skagit with AIS and DSC. The plotter shows AIS data on the plot in real time. No running over tow cables or infront of container ships.