DSC distress relays - Page 2

KnottyGurl · #11 11-13-2011

Just got off phone with Prescot Coast Guard, they siad two units with same mmsi is note allowed. This means that in your notrs with coasties you need to inform of other number so they know which is fixed units and which is hand held. I have a called into transport Canada as well to see what they suggest as they issues my mmsi numbers.
Will update responses from both.

Minnewaska · #12 11-13-2011

Quote:

Originally Posted by KnottyGurl

Just got off phone with Prescot Coast Guard, they siad two units with same mmsi is note allowed. This means that in your notrs with coasties you need to inform of other number so they know which is fixed units and which is hand held. I have a called into transport Canada as well to see what they suggest as they issues my mmsi numbers.
Will update responses from both.

Are you sure you asked the question clearly? The MMSI is issued to the boat with its station license and loaded into its radio. If you have mulitple radios on the boat, I understood they all load the same MMSI, including the boat's handheld. However, you could not use that handheld on another boat, which may be what the CG was saying.

I have my boat's single MMSI loaded into the VHF, SSB and gps Handheld in the ditchbag.

KnottyGurl · #13 11-13-2011

Yes I asked and explained clearly and he said that each radio east supposed to have seperate numbers and they WILL track both numbers to the same boat.
He said whichever units sent distress would be acknowledged if same mmsi was used.
Then he referred me to tech support and I left msg, he also took my info and mmsi to forward my questions to his supervisor for follow up.
He was surprised when I said I was goimg to use my original mmsi with hand held.
So I will get info monday amd update what Canada coasties are requiring

fairbank56 · #14 11-13-2011

Different rules for different countries. In the UK for example, they have set aside a group of MMSI numbers for handhelds only and under no circumstance, are you to use the boats MMSI in your handheld. In the US, if the handheld is permanently associated with the vessel, you use the vessels MMSI. Otherwise, for use in US waters only, you can used an MMSI issued by Sea Tow or Boat US. Apparently, this problem is under review but I don't know what the latest is on what they are going to do about it.

http://sailmagazine.com/experts/comm..._mmsi_for_all/

If you fall overboard and send a distress call, only a shore station should ack the call. Any other vessel including your own that receives the alert does not and should not ack a distress alert.

Eric

KnottyGurl · #15 11-13-2011

So the magizine article is more inline with what Canada CG was telling me that handhelds requires its own number and they will update their notes to show both units as same boat and owner and which is fixed unit and portable.
At least I try to keep CG updated on file with equipment onboard and reguler inspections.

goboatingnow · #16 11-13-2011

Quote:

Originally Posted by fairbank56

Different rules for different countries. In the UK for example, they have set aside a group of MMSI numbers for handhelds only and under no circumstance, are you to use the boats MMSI in your handheld. In the US, if the handheld is permanently associated with the vessel, you use the vessels MMSI. Otherwise, for use in US waters only, you can used an MMSI issued by Sea Tow or Boat US. Apparently, this problem is under review but I don't know what the latest is on what they are going to do about it.

One MMSI For All?

If you fall overboard and send a distress call, only a shore station should ack the call. Any other vessel including your own that receives the alert does not and should not ack a distress alert.

Eric

The ITU regulations state that an MMSI is assigned to the ship not the radio. Hence all radios onboard are programmed with the same number. That is the default situation.

However the ITU has recognised both becuase of AIS sarts and the proposed Class H DSC handheld, that there is a need to deal with the situation.

Some countries have forged ahead and implemented solutions. The UK has brought out, along with the standard ships license, a portable ships license, you can have as many portable ships licenses as handhelds and each gets its own MMSI. You CANNOT use these handheld outside the territorial waters of the UK ( In this regard its like the US only BoatUS MMSI)

NOTE. If you do not have a portable ships license, Then you ARE required to confirm to the ITU standard, which is one MMSI per ship in all radios.

This is the case for FCC obtained MMSIs in the US.

Dave

fairbank56 · #17 11-13-2011

Quote:

Originally Posted by goboatingnow

NOTE. If you do not have a portable ships license, Then you ARE required to confirm to the ITU standard, which is one MMSI per ship in all radios.

That only applies to FCC issued MMSI's. If you have an MMSI issued by Sea Tow or Boat US and only operate domestically, you can get a different number for your handheld from them without having a portable license.

Eric

fairbank56 · #18 11-14-2011

Did a little experiment this morning with 3 Icom M504's all programmed with the same MMSI and all set to auto-ack. Did a polling request from one and the other two responded at the exact same time. Tried this several times and only once did the polling radio get an ack from one of the others. Since they are xmitting at the same time there is a collision of signal data. Normally, and in accordance with ITU DSC technical specs, DSC transmission only occurs if the channel is clear except in the case of a distress alert, but since the two radio's received the request at the same time, they xmitt an ack at the same time. In your scenario with two handhelds on two different boats at different distances, one would likely get through with an ack due to the capture effect of fm receiver's but never both. If the handhelds are not set to auto-ack and require user input, the likelyhood of two users transmitting an ack at the exact same time are pretty slim.

Eric

KnottyGurl · #19 11-14-2011

Ok, just got off the phone with Coast Guard Prescott, their position is seperate MMSI numbers for hand helds. If you fixed sends DSC and you are bailing out and then use handheld they will belive your vessel is still in tact. If second dsc pushed from handheld they will still assume your on vessel and you could be in life raft or dink.
If second DSC call comes from different number they will open hailing and verify again.
With the tombstone database, the second number if you have informed the CG with a master sail plan, they will have on file name, address, phone numbers, vesssel reg, vessel type , sie and all equipment on board plus your capabilities and experience. When the second different comes in and flags the file for other numbers listed on the first screen, they would now know that the second was handheld and then go into MOB rescue.
You can use the same but CG reccommends that a seperate number be asssigned and that you file a master sail plan with them so they know who and what and where you are.
Also when you go crusing you can email phone or fax into them your intended route time out and they can monitor your trip, if you do not let them know your return was ok, they will then based on your plan start a search and rescue operation automatically as you are considered lost.
So the DSC feature opens a whole new concept to sailing and boating.
re cap, get seperate numbers for all handhelds on your vessel and create a sail plan with CG so they link the MMSI nubers to the same file.

btrayfors · #20 11-14-2011

Yeah, it introduces a degree and level of complexity which is bound to confuse things. For the operator. For the Coast Guard. For other boats.

Some see DSC as a blessing. I'm not a fancier, since I doubt if ANYONE out there will have the same understanding as others. Multiple users of complex systems not having a common understanding is a recipe for disaster.

It needn't be so messy, but it is. Mixed signals from ITU, local jurisdictions, manufacturers, users, and "testers". Clearly, from the video even the USCG has only a foggy notion -- mostly incorrect -- of DSC operation.

Even the MMSI number itself isn't inviolable: the U.S.-only MMSI number issued by Boat U.S. and by others is different from and not as useful as the FCC-issued MMSI number recognized by the ITU. Now, the UK is joining the mess. What a clusterf..k (to use a technical military term).

Basically, DSC is just like the SELCALL system used by aircraft. That system works very well. If only the basic DSC function(s) were used -- at least in the beginning until everyone understands and is comfortable with the system -- it mightn't be so misunderstood.

Let's see now, how do I initiate or respond to a 'group call' ?

IMHO,

Bill