Using DSC

[colbysmith]

I had first replied with this comment to another thread, but feel it should have it's own related thread:

Bob, regarding DSC. I don't know what the commercial requirements are, but I doubt most folks know how to use it, or even have it hooked up properly. This past summer I made several attempts to use my DSC to contact other vessels, both commercial freighters and small private yachts. None of which replied back. TO be honest, I don't even know if my radio's DSC is working properly as I have made numerous attempts in the Door County area to send the test code to the USCG, with no response. However, I also sent a test out in Port Washington, and got an immediate reply. (So I think my radio's DSC IS working. But to be sure, I have it at the manufacturer now to be checked out.) Finally, while I got no reply back to my test signal while at the Alton gathering (near St. Louis), I did try using DSC to contact a private yacht at the end of the dock. (In these contacts with other boats, it is in connection with their AIS signals that I'm registering, and then trying to initiate contact using the DSC function. After not getting any response, I actually walked down and spoke to the owners. Come to find out, their radio was alarming (in response to my DSC call), but they didn't know what it was. After some conversation, they offered to "work" with me again on the calls, but were unable to figure it out on their end. (From what I understand, a receiving radio should change to the requested frequency and then the operator can acknowledge and continue the call.) While in the North Channel earlier this summer, I also requested the gentlemen that does the morning broadcast, to announce my MMSI, and ask any fellow boaters to try hailing me by DSC. I did not receive any calls.... Anyway, my point is, I question how many even know how to use their DSC? And it only works if it's connected to an external GPS, or has it's own GPS, to transmit location. Ok, sorry about getting off subject a bit. Think the captain did the right thing in firing off a flare! Colby

That pretty much explains the situation I've had trying to test the DSC function on my radio. I just spoke with tech services at Standard Horizon, and they said my radio tests out fine. They also did the DSC auto test there with the USCG, and got a reply within about 6 seconds. So my next question is, has anyone else used the DSC on their radio's, and done the test function with the Coast Guard? If so, did you get a response? Particularly in the Lake Michigan Sturgeon Bay or Mississippi River St. Louis areas?

 

[thataway]

Colby, I have not used the DSC function on my own radio, but it has alerted on several Maydays. In areas beyond shore station range, I have heard other stations relay to USCG, I have also observed nearby vessels respond to the distress.

I am sure that you are correct that few boaters understand DSC. Many radios (maybe the majority) are not programed with the MMSI number e(either the Boat US or FCC--and most boaters do not know the difference)

I don't know what the current situation on outside Vancouver Island is on Rescue, but many times in Canada, I found Lighthouse keepers relaying distress calls, with a lack of Canadian CG response, in remote ares. Thus the idea of DSC is alarming any boater's radio-and hopefully the boats will respond. The mechanisms of voluntary use of DSC for calling a single vessel, calling a group, or a distress DSC are all different.

Here is USCG protocol for DSC (and note that is is also on 2182 HF

Actions on Receipt of a Distress Alert

Ships receiving a DSC distress alert from another ship should normally not acknowledge the alert by DSC since acknowledgment of a DSC distress alert by use of DSC is normally made by coast stations only.

Only if no other station seems to have received the DSC distress alert, and the transmission of the DSC distress alert continues, the ship should acknowledge the DSC distress alert by use of DSC to terminate the call. The ship should then, in addition, inform a coast station or a coast earth station by any practicable means.

Ships receiving a DSC distress alert from another ship should also defer the acknowledgment of the distress alert by radiotelephony for a short interval, if the ship is within an area covered by one or more coast stations, in order to give the coast station time to acknowledge the DSC distress alert first.

Ships receiving a DSC distress alert from another ship shall:

watch for the reception of a distress acknowledgment on the distress channel (2187.5 kHz on MF and channel 70 on VHF);
prepare for receiving the subsequent distress communication by tuning the radiotelephony receiver to the distress traffic frequency in the same band in which the DSC distress alert was received, i.e. 2182 kHz on MF , channel 16 on VHF;
acknowledge the receipt of the distress alert by transmitting the following by radiotelephony on the distress traffic frequency in the same band in which the DSC distress alert was received, i.e. 2182 kHz on MF, channel 16 on VHF:
"MAYDAY",
the 9-digit identity of the ship in distress, repeated 3 times,
"this is",
the 9-digit identity or the call sign or other identification of own ship, repeated 3 times,
"RECEIVED MAYDAY".
NOTE - Ships out of range of a distress event or not able to assist should only acknowledge if no other station appears to acknowledge the receipt of the DSC distress alert.

Distress Traffic

On receipt of a DSC distress acknowledgment the ship in distress should commence the distress traffic by radiotelephony on the distress traffic frequency (2182 kHz on MF, channel 16 on VHF) as follows:

"MAYDAY",
"this is",
the 9-digit identity and the call sign or other identification of the ship,
the ship's position in latitude and longitude or other reference to a known geographical location,
the nature of distress and assistance wanted,
any other information which might facilitate the rescue.
Transmission of a DSC Distress Relay Alert

A ship knowing that another ship is in distress shall transmit a DSC distress relay alert if

the ship in distress is not itself able to transmit the distress alert,
the Master of the ship considers that further help is necessary.

The bottom line, is that any and all practical methods of requesting assistance should be used. On the way to the flare gun, you lift a red plastic piece and hit the button--from there it is automatic. If the boat is upside down, then that is not going to happen--but another reason to have a portable VHF with DSC. Such as: Standard Horizon HX870

http://standardhorizon.com/indexVS.cfm? ... Archived=0 Simrad, Icom, and Uniden also have DSC/GPS radios. The price is from $175, to over $500. I would choose the Standard Horizon, as the best value at about $220.

I agree, there is has not enough education given to the use of DSC, but I can assure you that there are lots of boaters using it--and they are probably not going to found on the Miss River or Lake Michigan.

 

[ssobol]

The DSC function and the distress function of current VHF radios are related but not identical features. You can use the DSC function of your radio without sending a distress signal.

The DSC allows you to call a particular receiver if you know its MMSI number. The usual analogy is calling a particular phone number. It only works if you know the number before you place the call.

A DSC equipped radio can send a distress signal which contains digital information such as MMSI number and position info. This simplifies rescue operations because the responders can know who you are, get position information, and boat description without someone having to read off a lat/lon from some other device (if you have it wired up right) and/or give this information over the radio.

Of course, a distress signal from a VHF radio has a limited range (about 25 miles from a good set up depending on terrain). A EPIRB or PLB has an effect range that pretty much covers the entire planet. I'm guessing that a distress signal from an EPIRB or a PLB will probably mobilize a rescue faster than a VHF DSC call (less verifying if it is a false or inadvertent message).

 

[hardee]

The DSC function and the distress function of current VHF radios are related but not identical features. You can use the DSC function of your radio without sending a distress signal.

True, but you cannot use either the DSC or Distress function unless #1- there is an onboard or online GPS input to the VHF, AND #2-there is an MMSI number programed into that VHF radio.

The DSC allows you to call a particular receiver if you know its MMSI number. The usual analogy is calling a particular phone number. It only works if you know the number before you place the call.

False, in part, because of the design of the Standard Horizon GX 2150 or 2200 VHF’s AIS screen mode, you have the option of a 1 or 2 button MMSI call directly off the AIS target list, without having to enter the MMSI number onto a keypad.

A DSC equipped radio can send a distress signal which contains digital information such as MMSI number and position info. This simplifies rescue operations because the responders can know who you are, get position information, and boat description without someone having to read off a lat/lon from some other device (if you have it wired up right) and/or give this information over the radio.

True. A serious time saver IF the VHF has the GPS input and an MMSI programmed.


From an article in a Boat US mag from a few months ago, I believe I remember, the estimated DSC capable VHF’s with MMSI numbers and GPS hooked up is somewhere just under 25%. I have had DSC capable VHF on my boat for 4 years now, and in that time, have received 4 calls to me, and have heard 25 or 30 position requests, or all station calls, and 2 emergency calls. I have only made 3 calls on DSC and only one of those were answered via DSC mode.

In my experience, including some SW Vancouver Island and central and northern Vancouver Island this summer, I was impressed with the ability to contact both Canadian Coast Guard, and Vessel Traffic in some very remote areas, which I did on several occasions for various reasons. If I could make that contact via VHF voice, I have no reason to think that a DSC call would not have been affected just as readily. (BTW, in Canada, for the MMSI to provide ID info, the MMSI must have been assigned by the US FCC.)

Harvey
SleepyC:moon

 

[ssobol]

I would think that you could use the DSC function to call someone else without a valid GPS to the radio.

I think that part of the problem is that once a radio has a MMSI number programmed, it can only be reset by a service center. You can transfer the MMSI number in the radio to another user when you sell the radio (instead of reprogramming it) but that involves some paperwork.

 

[hardee]

I would think that you could use the DSC function to call someone else without a valid GPS to the radio.

I think that part of the problem is that once a radio has a MMSI number programmed, it can only be reset by a service center. You can transfer the MMSI number in the radio to another user when you sell the radio (instead of reprogramming it) but that involves some paperwork.

You may be right on the calling without a GPS input, but I seem to remember when putting in my first DSC radio that the MMSI programming actuated the DSC functionality of the radio. In subsequent installations I do not remember that as being part of the instructions. Many of the DSC functions include position info, and they may all include it in the call process, just do not post it on the VHF screen.

As to the MMSI permanence, there are some VHF brands that do allow a one time (at least), reprogramming by the user.

Harvey
SleepyC :moon

 

[colbysmith]

DSC, either individual calling or distress, is not dependent upon GPS. However, it will not transmit your position if you do not have an internal GPS in the radio, or have it connected to your chartplotter. I'm not sure exactly how the MMSI number is tied in with everything, other than as a means to identify your radio. (And for the USCG to look up important data on you if you send the distress signal using DSC.)

Bob, I've only heard DSC used once in the few years I've had this radio. And that was an all call by the Canadian GC while I was in the North Channel last summer, looking for assistance with an overturned kayaker during all that wild wind that was blowing while we were there.

I'm just learning how it can be used for regular communications, but hard to really make use of it in my locations of boating. DSC use among C-Brats at gatherings would diffinitely be a benefit!

Colby

 

[rogerbum]

DSC, either individual calling or distress, is not dependent upon GPS. However, it will not transmit your position if you do not have an internal GPS in the radio, or have it connected to your chartplotter. I'm not sure exactly how the MMSI number is tied in with everything, other than as a means to identify your radio. (And for the USCG to look up important data on you if you send the distress signal using DSC.)
<stuff clipped>
Colby

The above is correct, one need not have the GPS hooked up for DSC calling to work - it just won't transmit your GPS position correctly. I've received a number of DSC distress calls while on my boat fishing off the coast. They definitely catch one's attention as the radio (in my case two Standard Horizon radios) switches to a high volume and alarms automatically upon receipt of a DSC distress call. When a GPS is hooked up to the sender's radio, since mine are properly hooked to my chart plotters, I get position of the boat making the distress call on my chart plotter. When the sender's radio is not hooked to a GPS (or doesn't have an internal GPS), I get some default coordinates sent in the message (I can't remember what they were but they might have been 0W, 0N). The MMSI number is registered to the boat so if one has multiple radios on board, they can share the same MMSI number. A properly registered MMSI number puts information about your boat and you into a database which can be used by the Coast Guard and other SAR units to potentially identify you. E.g. your name, address and phone number may help a SAR unit contact someone who knows where you are at, the boat name and type will help them know what they are looking for.

 

[thataway]

One important item to remember (and it brings up that old issue of a ship station license if you make "international voyages"!)

Many mariners use Boat US (and some other agencies) who assign a MMSI number, without a FCC ship station license. This information is transmitted to the US CG.

From the Boat US web Site:

Do NOT Register with BoatUS MMSI if:
your vessel is required to carry a radio onboard (“Compulsory Equipped”)
you plan to visit or communicate in a foreign port including Canada, Mexico, Bahamas, and the British Virgin Islands
If either of the above conditions apply, you are legally required to obtain a Ship Station License from the FCC. They will issue an appropriate MMSI with the License.

NOTE: when traveling to foreign ports, you are required to have a Restricted Radiotelephone Operator Permit holder aboard.

I'm guessing that a distress signal from an EPIRB or a PLB will probably mobilize a rescue faster than a VHF DSC call (less verifying if it is a false or inadvertent message).

As to an 406 mhz distress transmission by either a EPRIB or PLB would have been faster; Not likely. The reason is that a DSC transmission indicates a distress to the boats and shore stations in the immediate area instantly. The 406 mhz signal, has to get to a satellite, be downloaded by the International Mission Control center, then routed to the proper country, and proper SAR agency--is this a land rescue, or sea rescue--US or Canadian waters? Then that agency has to make phone calls to those contacts registered to the vessel or person and verify that it is mostly likely a distress (about 10% of the time). and finally dispatch help. This process often takes 30 minutes, often longer. There are a few cases where help has been dispatched (not arrived) in 15 to 20 minutes). Then there is a response time of the agency!
The DSC is far faster.

If you have DSC and the MMSI #, you really should have the GPS hooked up to be most effective--or with most of the new radios, it is built in (including the hand helds, I cited above.) There is a requirement for commercial vessels to have the EPRIB aboard, and it must be of a certain type.

 

[beermanPDX]

If you own at least two radios with DSC and have your MMSI number entered in them, you can test out DSC on your own.

Ex. I have two fixed mount radios and a handheld, all with DSC. They all have my MMSI number. If I send out a position request message to my own MMSI number, the other two radios get it. I can see and verify the messages and coordinates my radios are sending out.

 

[rogerbum]

Thanks for the reminder Bob. When I registered my MMSI number, I did it through the FCC for that very reason - e.g. I planned to be in Canadian waters and I wanted to not only have the license but to be sure that my MMSI number and info was in the international databases.

Rob - I don't know why I didn't think about that. I also have two fixed mount radios with MMSI# and DSC. Each one is attached to it's own chart plotter but on has an internal GPS (newer Std. Horizon) and the other does not. Both have AIS.

 

[colbysmith]

Regarding Canada and Boat US assigned MMSI numbers. While it is true that the MMSI numbers assigned by Boat US are only for use in "domestic" waters, in real life operation, if you are operating in "border" waters, Canada will very likely be able to get your MMSI information if you send out a DSC distress signal. So if you need to signal a distress and want to use DSC, USE IT. (I forget where I got this info, but it was from some official Canadian types somewhere while we were up in the North Channel.) And besides, if you have GPS hooked up, the most important thing is having a position to search in! Colby

 

[hardee]

Regarding Canada and Boat US assigned MMSI numbers. While it is true that the MMSI numbers assigned by Boat US are only for use in "domestic" waters, in real life operation, if you are operating in "border" waters, Canada will very likely be able to get your MMSI information if you send out a DSC distress signal. So if you need to signal a distress and want to use DSC, USE IT. (I forget where I got this info, but it was from some official Canadian types somewhere while we were up in the North Channel.) And besides, if you have GPS hooked up, the most important thing is having a position to search in! Colby

Maybe we could get some input from some of our Canadian friends on this. Maybe Martin and Andrea, or others, could give us some practical experience info.

My understanding, if you are in Canadian waters, the call would be answered by Canada Coast Guard, not US, and I don't believe that Wast Marine MMSI's are entered into the international data base, so, IF they could or would get the info, there would certainly be a time delay.

Harvey
SleepyC :moon

 

[rogerbum]

They will get the distress call and your position. They will probably not get the info associated with you MMSI #. But the position is the most critical piece of info and I doubt there would be a delay in response.

 

[hardee]

Roger, you are right there. And I doubt they would even go looking for the other info.

One thing I learned from this thread and reading about rescues where the guy in the water watches the helo come right toward him and the turn and go away.

Put my MMSI numbers into my Handheld VHF's.

Never even thought about that. Thanks C-BRATS, What a great place.

Harvey
SleepyC :moon

 

[thataway]

An EPIRB or PLB will have a 121.5 Mhz beacon. This is no longer picked up by Sat SAR satellites, but the chopper and CAP planes will sill home on the 121.5 Mhz beacon. They can also home on any VHF channel, with an RDF. This is a good reason to have the hand held vhf. I am sure that you can home on the channel 70 DSC as well as channel 16.

But, as we found out with our "rescue" at Lake Powell, the park service, and I have seen this with some marine patrols, and Sheriff's offices. They will be listening preferentially to their dispatcher, rather than channel 16. I asked the ranger--and he said he had two park service radios, and although he had the marine VHF--he had to keep listening to the park service frequencies.--and he had ear pieces in for those--thus did not hear the VHF.

Good idea to have a mirror, flare, smoke,sea dye, strobe etc, if you want to get rescued.

 

[hardee]

On a couple of occasions I have had the opportunity to talk to the USCG helo as they pass on patrol. I have hailed them on 16 and had very quick responses. On one occasion I asked if they would mind if I tried the hand held. They oked it and I did a short call, with a good response. They were about 3 miles away at the time, definitely line of site still, but I wondered about the range. They assured me that if I could see them , they would be able to hear my handheld VHF transmit on 16.

I wonder if, because of the difference in location, the CG helos here are monitoring on 16 as well as there home ops frequency

Harvey
SleepyC :moon

 

[thataway]

Yes, the CG vessels and other assets, including airplanes and Choppers will always be monitoring 16. They should have a person dedicated to the monitoring of radios, other than the pilot. (Often the case in the vessels also). We were aboard one of the 87 footers and the radio room was down one level from the wheel house on that vessel. The larger CG cutters also have Marine SSB, and can transmit on Ham frequencies also. (I have a commercial SSB radio which has been "fixed" by the factory, so it does all of the ham, as well as military frequencies--Don't use it for anything other than Marine SSB, and as a back up for ham when we were cruising.)

 

[AstoriaDave]

Harvey,

Re: range of a HH VHF to a helo:

I have had good reception and transmission to the Tofino CCG repeater atop the peak just N of the opening to Barkley Sound, from about 5 miles away line of sight, standing on the beach, and usable TX/RX to Hot Springs from Burnaby Narrows, Queen Charlottes, again standing on the beach, a distance of 8 or 9 miles. The Hotsprings Haida Watchmen were working a whip off fhe cabin roof, so that I am sure an airborne helo would match that reception.

I am confident a helo should be able to pick you up easily at 10 miles out.

 

[hardee]

Thanks Dave, and Bob.

So far, instead of a PLB or EPIRB, I have made it a habit of having my Handheld VHF on my PFD. If I am in the water, I can talk to the helo, not just rely on there sight or bearing. And just in case, I'm planning on being in a doughnut boat instead of in the water.

Harvey
SleepyC :moon