DSC Basics

[gamayun]

Originally Posted by ka4wja

gamayun,
I agree with you!!
And, this is why I made the Youtube videos!!
Please watch the videos....all of them in this playlist....and I think you'll learn a lot!!
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX

While I suggest you watch the whole playlist, start-to-finish, IN ORDER #1 thru #15, as this will give you the best understanding of DSC, as well as many LIVE, real-world demonstrations (not lab-simulated, but REAL, LIVE, demonstrations from on-board a typical cruising/voyaging sailboat)....
You do NOT have to watch them all at once!!

Ah, yes, I did not see the YouTube link. Thanks for that. I will certainly watch and will report back -- tout de suite

[Rustic Charm]

Originally Posted by gamayun

John, my son sometimes responds to info I send him with "tldr." Google it. When I got into boating a few years ago, I would research the hell out of everything because it was all new and I was so green. Still am, but this issue about DSC and how to use it is NOT easy to understand. It's really not so simple as "just read the regs." Few people have the capacity to read and directly apply the written rules to every day actions, much less in a possibly frantic and confusing emergency situation. I go through the Colregs all the time, but unless there's some context (such as questions posted in these forums), they are not the most intuitive to understand or remember completely. People might say 'that's irresponsible,' but I'll bet you that most people also get their drivers' licenses without knowing every single rule of the road. It's just reality. What we need are practical applications of DSC. This thread is helping with that by clearing up some misconceptions, and maybe it will also encourage more people to go out and start using their DSCs for non-emergency communications (IIRC, that was the point of the OP). With all due respect and much appreciation to your website, asking people to read about GMDSS, its history, purpose, structure, and capabilities, is not that useful for the rare time when someone might hear the DSC alert coming over their radio, and has to make a decision about what button to push.

yeah, what she said (better than I put it).

[gamayun]

Originally Posted by Terra Nova

Distress call & DSC procedures should be posted at the com station.

Great point. I have been meaning to do the former for a while now, and this post makes me realize that the latter is just as important. It will be on my TO DO list for tomorrow at the boat

[transmitterdan]

DSC usage on a VHF isn't complex. Ignoring the distress functions there are a couple of "cool" things you can do. One is you can call another radio like you dial a cell phone from a phone book. Instead of phone numbers you use what are known as MMSI numbers. The MMSI number comes from your local country. In the US you can get them from the FCC or from Boat US.

Another "cool" thing you can do is send your exact position to another radio by using its MMSI number.

Another "cool" thing is you can ask another radio to tell you it's position. If the other radio is allowed then it will answer. The position request feature can be answered either manually or automatically. The MMSI number of the requesting radio does not have to be different than the answering radio. Thus you can have a DSC handheld and fixed radio with the same MMSI number and the handheld can request the location of the fixed radio or vice versa. This is very handy when crew are away from the mother ship and if the mothership seems to have gone missing the crew can ask its whereabouts. Likewise if the crew seem to be missing the mother ship can request their whereabouts.

The procedures are different for each brand and model. So decide which feature you want to use and post a short instruction for your setup. The DSC handhelds I have seen make it obvious how to make calls and request position. The shipboard units are not so obvious so a brief write up at the radio is helpful.

[hellosailor]

"For a hand held DSC VHF radio, that will be assigned a mobile MMSI"
I had heard the ITU was considering the topic, but as of now is this just a UK policy?
Or have the ITU made an upgrade to the numbering policy, currently accepted by the FCC and USCG in the US and others as well?

[ka4wja]

Rustic Charm,
Sorry, I assumed that you wanted the supporting docs, as that is what you asked for, here...

Originally Posted by Rustic Charm

Do you have a link to where it's from? It reads as ' recommendations' and the AMSA sight advises quite clearly that as yet, Australia is not using the DSC system with coastal stations as yet. I don't believe AMSA even monitors DSC. Though, happy to be corrected if that's not accurate.

So, this is what I gave you...the direct links to the AMSA info, where you will find all the details that show that Australia / AMSA does have a full DSC network, and has had one for more than 17 years....but, instead of using VHF-DSC and/or MF-DSC (which would typically be used to cover Sea Areas A1 and A2, respectively), Australia designated ALL their waters Sea Area A3, and cover all their waters and the waters they are responsible for with HF-DSC...


The fact that they haven't set-up VHF-DSC (nor MF-DSC) stations, does not mean that DSC (nor the GMDSS) is new to Australia....in fact DSC has been a part of AMSA for more than 17 years....
But, I do thank you for pointing out that this new to many yacht chandleries in Australia (this is something I was NOT aware of, and I thank you for informing me and all of us, of this!!!)




Also, I apologize if my words seemed too strident....not my intention at all!!
Sorry about that mate!!!


{But, fyi, there were some here in this thread that were posting that DSC radios relay Distress alerts/calls, which they do NOT, and others were using that false info to make further assumptions about distress signaling, and possibly equipment selection, etc....
so, I thought it would be prudent to correct this...
I hope this in understood...}



But, if all you really need is layperson explanations of how things work...

Originally Posted by Rustic Charm

yeah, what she said (better than I put it).

Then, please watch the videos and read what I wrote above...


Just for simplicity...I'll post it here again:
Please watch the videos....all of them in this playlist....and I think you'll learn a lot!!
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX

While I suggest you watch the whole playlist, start-to-finish, IN ORDER #1 thru #15, as this will give you the best understanding of DSC, as well as many LIVE, real-world demonstrations (not lab-simulated, but REAL, LIVE, demonstrations from on-board a typical cruising/voyaging sailboat)....
You do NOT have to watch them all at once!!
If you don't have the time for them all (an hour and a half), then please at least watch the ones that pertain to your specific application...

Please note that the reason I made the "playlist" and laid the videos out in a specific order, is so that the average layperson sailor would be able to quickly / easily get the gist of the GMDSS as well as understand the how and why....and then, they get to the "live demonstrations", otherwise you'd just see someone press some buttons, but never really learn what, why, and how...??


Video #1 explains what DSC is, in detail, with average layperson sailors in mind...(albeit, focusing on the more complicated HF-DSC....it is very similar to VHF-DSC)

Video #10 is Icom's basic VHF-DSC demonstration...

Videos #13, 14, and 15, form Paul Harrison in the UK, deal specifically with VHF-DSC radios (from Icom and SH)



And, understand that the 24 year old GMDSS video (video #12) does have some errors/out-dated info....but as long as you watch it AFTER the preceding videos, these errors / out-of-date info will not effect your understanding of the GMDSS...
{An OLD GMDSS explanation video (from 1992). Please ignore the errors from19m 23s to 19m 36s, showing MF/HF and VHF radios that do NOT have DSC capabilities and note the old external DSC controller shown from 20m 17s to 20m 24s.
Also ignore the references to the defunct INMARSAT-E beacons.
Further take note of the old "2182khz Watch Receiver", which haven't been used in almost 20 years (at 20m 54s), shown listening to static (which they didn't do, as they were typically squelched and listening for a two-tone alarm generator alert (NOBODY monitors 2182khz anymore!)
Even with the above errors and 20+ year old technology shown, it does give a good overview to how the GMDSS was conceived and how it works!}




BTW, I have many other videos, arranged in playlists, that might be helpful to some looking for clarifications on other subjects...

Maritime HF Communications (in general)
https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y


Offshore Weather Sources and Reception
https://www.youtube.com/playlist?lis...zdjTJjHlChruyY


Icom M-802 specific instructions and explanations
https://www.youtube.com/playlist?lis...rC-8QKVyMb4tVr


And, just for fun, some Atlantic Crossing videos of mine...
https://www.youtube.com/playlist?lis...KgTCj15iyl6qoY

(the GMDSS was established by the IMO under the SOLAS conventions in 1988, and became fully effective/operational in Feb 1992....and became mandatory for all SOLAS vessels and signatory nations in Jan 1999...)

So, this is nothing new....and we should all have been fully aware of the GMDSS now for at least the past 15 years, and have made every effort to utilize what parts of the GMDSS we can....


Parts of the GMDSS system that most find easy/affordable/useful (all within easy reach / affordable parts of the GMDSS for cruising boats...):

--- 406mhz EPIRB's (relatively inexpensive at $400 - $700, and easy to "sell" to cruising sailors..)

--- Marine VHF-DSC-FM (cheap and almost ubiquitous now-a-days...anyone that doesn't have a Class D VHF-DSC, REALLY needs to spend the few hundred dollars now!!!)

--- Marine MF/HF-DSC-SSB (HF-DSC is a VERY robust/reliable means of signaling.....and with reasonable costs of ~ $1800 new, ~ $1000 used, for an Icom M-802 MF/HF-DSC-SSB Radiotelephone....and simple-to-use, robust and reliable...it is an easy "sell", almost a no-brainer!!)

--- NAVTEX (inexpensive and very useful for most coastal sailors and/or those plying the Med, etc., with typical forecasts for waters out to 150 - 200 miles....but in some areas the forecasts are only for the next 24 hours, so other weather sources, such as HF-WeFax are recommended...) (and in US waters, the VHF-based NOAA Weather Radio system is widely used, so NAVTEX hasn't caught on in the US, as it has in Europe and the Far East...)

{- WeFax....And while HF WeFax was not adopted officially as part of the GMDSS, according to a 2012 survey by the Joint WMO/JComm group, HF comms, DSC, voice, and data are used daily by a majority of ocean going vessels, and HF wefax being reportedly used daily by > 85% of them....so, for offshore/hi-seas weather info/forecasts beyond the "text" weather info provided via INMARSAT-C and some HF coast stations, HF WeFax still rules as the predominate "1st choice" when offshore, even in 2012, even for large ships / SOLAS vessels....) }


Parts of the GMDSS that are a bit more expensive:

--- INMARSAT-C,
While INMARSAT-C might seem to some to be a bit pricey, at ~ $3000 - $3500, is a VERY viable communications tool to have on-board long-range cruising boats...as it gives, thru its FREE "SafetyNet" service, offshore/hi-seas weather info/forecasts (in plain text), position reporting and weather reporting thru NOAA and AMVER, and Distress Signaling....ALL FOR FREE....
NO monthly/annual subscription, NO Fees at all, until/unless you use it to send regular e-mails, and then you're just billed by the character/letter....
(and it is very robust/reliable....many orders of magnitude better than a handheld sat phone!!)


--- INMARSAT Fleet systems (such as F77) are pricey at $15,000 - $20,000 and are big/heavy, and use significant amounts of electrical power....
So, here if cruiser's desire hi-speed data / broadband internet access / etc., Iridium Pilot or INMARSAT Fleet Broadband systems (at ~ $4500 - $5000) are usually the typical choices....

[please note that INMARSAT is in the process of getting FB250 and FB500 systems GMDSS certified/compliant...and by end of 2017, they should be able t be installed innplace of Fleet 77 for GMDSS compliance...
But, costs will still be too high for us cruising sailors!! ]

--- SART's (X-band radar Search And Rescue Transponders) are reasonably priced at $600 - $800.....but are often over looked by many cruising boats, as they figure a working EPIRB in their liferaft will do them better...
And, if deciding between a second 406mhz EPIRB and a SART, I'd choose the second EPIRB!!! (but, if you're cruising in heavily-trafficked areas, with poor visibility, such as UK/North Sea, etc. then a SART would be a GREAT idea, and I'd recommend one before a second EPIRB...)


Anyone talking about "Marine SSB" in the last decade or two, should be talking about MF/HF-DSC-SSB....and those that are talking about 25 year old radios and "Voice radio watchstanding", etc. are unfortunately either ignorant of the changes in the past 25 years or are laboring under some serious misconceptions???

While it is not a requirement for our pleasure craft, the GMDSS has been a mandatory system for all SOLAS vessels, and all signatory nations, since Jan 1999....over 15 years ago...and regarding "SSB", please remember that nobody (except the USCG, Aus and NZ, etc.) does any "SSB Voice" monitoring or watchstanding anymore...and haven't for decades....

(as most "radio watchstanding" in the 1970's, 1980's and early 90's, before the GMDSS was fully implemented, was via "2182 watch receivers", which were silent until they received a two-tome alarm signal from another like-equipped merchant vessel, etc....so, understand that for most of the past 40 years, aside from the USCG, Bermuda Radio, Portishead Radio, Olympia Radio, Aus, NZ maritime shore stations, etc. and the old HF Hi-seas public coast stations, nobody has maintained a SSB Voice radio watch for many decades....and now in the recent 20 years, since the GMDSS has been implemented, and most HF Hi-seas public coast stations have closed, they are all monitoring MF/HF-DSC, 24/7....NOT an "SSB" Voice watch...)

{When I write "they", I'm speaking about the > 80 HF-DSC shore stations worldwide monitoring for HF-DSC signals 24/7, from all over the world....and the > 450 MF-DSC shore stations worldwide, that are monitoring MF-DSC 24/7, from vessels within 150 - 250 miles offshore....[and the 1000's of VHF-DSC Coasts Stations], and the many hundreds/thousands of SOLAS grade vessels plying the seas/oceans worldwide 24/7 (many of them could be within a few hundred miles of you, < one day away...remember 500 miles can be covered by a container ship in less than 24 hours).... but again, except for the USCG, and a couple of others, nobody has a Voice radio watch anymore, and haven't for 15-20 years....all initial contact/signaling is done by DSC, and then further contact/coordination is done via "SSB Voice", only after signaled by DSC (or INMARSAT-C).... [or if in VHF-range, is done via VHF-DSC and then via VHF-FM Voice]}

I hope the above helps...

Fair winds...

John

[conachair]

Originally Posted by hellosailor

"For a hand held DSC VHF radio, that will be assigned a mobile MMSI"
I had heard the ITU was considering the topic, but as of now is this just a UK policy?
Or have the ITU made an upgrade to the numbering policy, currently accepted by the FCC and USCG in the US and others as well?

Apparently still in discussion. Ofcom in the UK are actually very good at what they do so if anyone would know, good chance they would.

Hand held VHF DSC FAQs | Ofcom

Why has this taken so long?
Any new DSC apparatus must fit into existing arrangements, notably the GMDSS. It has taken a long time for the international community to draft standards under which hand held VHF DSC can operate. These have almost been agreed, so we can refer to them for the purposes of authorising the use of the apparatus in UK waters. When they have been agreed fully, we anticipate that an international authorisations regime can be agreed.

What about the future?
Some the internationally established parameters may change, leading to a need for changes in the way that VHF DSC is used or authorised. For example, an MMSI format may be adopted that differs from the 2359xxxxx format described above. Users would then have to get a new MMSI from us and have it programmed into their set. Dealers would advise how to do this, as sets can often not be reprogrammed by users.

Seems like a similar situation in the US for now, as they do their own MMSI numbers internally handhelds can have the same number as the ship. But only at home, not GMDSS MMSI numbers issued by the FCC.

http://www.navcen.uscg.gov/?pageName=mtMmsi

Obtaining MMSIs for DSC-equipped VHF Handhelds

A handheld VHF transceiver with DSC and an integral global navigation satellite system (e.g. GPS) not intended for dedicated use on a particular ship (e.g. a diver’s radio) should be assigned a unique 9-digit number in the format 81M2I3D4X5X6X7X8X9. While currently means do not exist within the U.S. to assign such identities, the Coast Guard has been in discussions with the Federal communications Commission and others on implementing them.

In the interim, VHF handhelds used in the United States should use the MMSI assigned to the ship to which the handheld is primarily associated, even if another radio on that ship uses the same MMSI. Non-commercial users of VHF handhelds not primarily associated with any single ship may use an MMSI provided by an organization such as BOAT US, SEA TOW and U.S. Power Squadron (see above). VHF handhelds should not be used ashore absent FCC or NTIA authorization allowing such use.

[Sandero]

John,
Thank you. I was away all day and have a lot of reading in this thread and vids to watch.
I hope I have no questions... but I probably will. I have my homework!

[belizesailor]

Originally Posted by svGenesis

Very nice link...Explains it all!

I'm surprised it didn't come up in the ASA104 class i recently did as they covered the VHF and other safety functions very well.

Not part of the standard, but not a bad idea to add...I will suggest.

[nigel1]

My apologies for muddying the waters with my descriptions of DSC which were more suited to Class A operations rather than Class D (I'm more used to Class A)

At least this thread has opened up some interesting discussions, and we have all learned something.

An overall view of the GMDSS DSC system is good to have, most importantly, if you do get a DSC Distress alarm in coastal waters, know to wait a few minutes to allow a Coast Station to respond first (unless in Aus )

[Rustic Charm]

Originally Posted by ka4wja

Rustic Charm,
Sorry, I assumed that you wanted the supporting docs, as that is what you asked for, here...So, this is what I gave you...the direct links to the AMSA info, where you will find all the details that show that Australia / AMSA does have a full DSC network, and has had one for more than 17 years....but, instead of using VHF-DSC and/or MF-DSC (which would typically be used to cover Sea Areas A1 and A2, respectively), Australia designated ALL their waters Sea Area A3, and cover all their waters and the waters they are responsible for with HF-DSC... Ok, I get it this time round thanks HF DSC, not VHF DSC


The fact that they haven't set-up VHF-DSC (nor MF-DSC) stations, does not mean that DSC (nor the GMDSS) is new to Australia....in fact DSC has been a part of AMSA for more than 17 years....
But, I do thank you for pointing out that this new to many yacht chandleries in Australia (this is something I was NOT aware of, and I thank you for informing me and all of us, of this!!!)

Yep, and you have grasped what I was saying. DSC might be 17 years old in Australia, but it's only in the past ten years at the most, more like last two or three years that there has been any real significant knowledge about it. In this sense it is a new technology to many in the boating world in Australia.


Also, I apologize if my words seemed too strident....not my intention at all!!
Sorry about that mate!!!


{But, fyi, there were some here in this thread that were posting that DSC radios relay Distress alerts/calls, which they do NOT, and others were using that false info to make further assumptions about distress signaling, and possibly equipment selection, etc....
so, I thought it would be prudent to correct this...
I hope this in understood...}

yep, loud and clear.

But, if all you really need is layperson explanations of how things work...Then, please watch the videos and read what I wrote above...

Yep, just a layperson's view will do me fine. I'll start watching the vids now.

Just for simplicity...I'll post it here again:
Please watch the videos....all of them in this playlist....and I think you'll learn a lot!!
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX

While I suggest you watch the whole playlist, start-to-finish, IN ORDER #1 thru #15, as this will give you the best understanding of DSC, as well as many LIVE, real-world demonstrations (not lab-simulated, but REAL, LIVE, demonstrations from on-board a typical cruising/voyaging sailboat)....
You do NOT have to watch them all at once!!
If you don't have the time for them all (an hour and a half), then please at least watch the ones that pertain to your specific application...

Please note that the reason I made the "playlist" and laid the videos out in a specific order, is so that the average layperson sailor would be able to quickly / easily get the gist of the GMDSS as well as understand the how and why....and then, they get to the "live demonstrations", otherwise you'd just see someone press some buttons, but never really learn what, why, and how...??


Video #1 explains what DSC is, in detail, with average layperson sailors in mind...(albeit, focusing on the more complicated HF-DSC....it is very similar to VHF-DSC)

Video #10 is Icom's basic VHF-DSC demonstration...

Videos #13, 14, and 15, form Paul Harrison in the UK, deal specifically with VHF-DSC radios (from Icom and SH)



And, understand that the 24 year old GMDSS video (video #12) does have some errors/out-dated info....but as long as you watch it AFTER the preceding videos, these errors / out-of-date info will not effect your understanding of the GMDSS...
{An OLD GMDSS explanation video (from 1992). Please ignore the errors from19m 23s to 19m 36s, showing MF/HF and VHF radios that do NOT have DSC capabilities and note the old external DSC controller shown from 20m 17s to 20m 24s.
Also ignore the references to the defunct INMARSAT-E beacons.
Further take note of the old "2182khz Watch Receiver", which haven't been used in almost 20 years (at 20m 54s), shown listening to static (which they didn't do, as they were typically squelched and listening for a two-tone alarm generator alert (NOBODY monitors 2182khz anymore!)
Even with the above errors and 20+ year old technology shown, it does give a good overview to how the GMDSS was conceived and how it works!}




BTW, I have many other videos, arranged in playlists, that might be helpful to some looking for clarifications on other subjects...

Maritime HF Communications (in general)
https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y


Offshore Weather Sources and Reception
https://www.youtube.com/playlist?lis...zdjTJjHlChruyY


Icom M-802 specific instructions and explanations
https://www.youtube.com/playlist?lis...rC-8QKVyMb4tVr


And, just for fun, some Atlantic Crossing videos of mine...
https://www.youtube.com/playlist?lis...KgTCj15iyl6qoY



I hope the above helps...

Fair winds...

John

Thanks John, much appreciated.

[Rustic Charm]

Originally Posted by ka4wja

Rustic Charm,






But, if all you really need is layperson explanations of how things work...Then, please watch the videos and read what I wrote above...


Just for simplicity...I'll post it here again:
Please watch the videos....all of them in this playlist....and I think you'll learn a lot!!
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX

While I suggest you watch the whole playlist, start-to-finish, IN ORDER #1 thru #15, as this will give you the best understanding of DSC, as well as many LIVE, real-world demonstrations (not lab-simulated, but REAL, LIVE, demonstrations from on-board a typical cruising/voyaging sailboat)....
You do NOT have to watch them all at once!!
If you don't have the time for them all (an hour and a half), then please at least watch the ones that pertain to your specific application...

Please note that the reason I made the "playlist" and laid the videos out in a specific order, is so that the average layperson sailor would be able to quickly / easily get the gist of the GMDSS as well as understand the how and why....and then, they get to the "live demonstrations", otherwise you'd just see someone press some buttons, but never really learn what, why, and how...??


Video #1 explains what DSC is, in detail, with average layperson sailors in mind...(albeit, focusing on the more complicated HF-DSC....it is very similar to VHF-DSC)

Video #10 is Icom's basic VHF-DSC demonstration...





BTW, I have many other videos, arranged in playlists, that might be helpful to some looking for clarifications on other subjects...

Maritime HF Communications (in general)
https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y


Offshore Weather Sources and Reception
https://www.youtube.com/playlist?lis...zdjTJjHlChruyY


Icom M-802 specific instructions and explanations
https://www.youtube.com/playlist?lis...rC-8QKVyMb4tVr


And, just for fun, some Atlantic Crossing videos of mine...
https://www.youtube.com/playlist?lis...KgTCj15iyl6qoY



I hope the above helps...

Fair winds...

John

Just watched the first one, which is on the HF DSC.. does a vhf DSC also have the ability to send those four types of messages?

Also, in Australia, does Australia operate shore based services to receive DSC messages like in this video?

And thirdly, I understand the 'test' feature doesn't work in Australia. Is that true? or is it just true in relation to VHF DSC?

[Prairie Chicken]

Quote:
Originally Posted by Sandero View Post

Curious... how loud are the alarm tones? Can they be tested and the volume adjusted?

1st, The alarms are loud & have you jumping for a button to silence it. It is important to know which button to push to responsibly make the klaxon sound go away. Your manual will tell you.

2nd, DSC cannot be tested, & should not be tested. (But see next para.)

I believe much of the confusion stems from new developments in DSC radios. For example, when I took the DSC radio course last year, we were taught in no uncertain terms that the DSC distress function should NEVER be tested & MAY NOT be tested. From this thread I'm reading there are now radios which have a test function. Our 1-year old radio does not have a test function. Obviously something is changing.

Our instructions (Canadian Power Squadron) were to NEVER accept a distress call unless you were actually prepared to participate in the rescue or verbally relaying the distress call... but the manual of our then newly released Horizon Matrix 2200 DSC-VHF clearly states you may accept the call.

Short story, get an understanding of the concepts of VHF-DSC, then read your manual. It isn't that tough to understand, but complex enough that a thread such as this makes it sound very confusing. Also, the new radios have so many features that remembering those infrequently used functions takes some review every year when you get back on the water.

[colemj]

Originally Posted by nigel1

most importantly, if you do get a DSC Distress alarm in coastal waters, know to wait a few minutes to allow a Coast Station to respond first (unless in Aus )

No, this is still bad advice. A class D DSC cannot cancel a distress call from another vessel, so there is no problem acknowledging one when it occurs. In fact, "waiting a few minutes" is exactly the WRONG action to take (especially for your own ears). Go ahead and press "Accept", get the information and see if you are in a position to help. Doing so won't interfere with the coast guard or the ship in distress.

The only way a class D DSC distress call can be cancelled is for the distressed ship operator to specifically push the "cancel call" button on their radio.

Mark

[Rusty007]

For most recrational boaters with a normal Class D radio, You can do nothing that would disrupt a recived distress call.

If you have recieved one you should always accecpt the call as this will then give you the details of the distress. If you have your radio linked to your chart plotter then you will also see the location displayed there.

Remember that you may be the only person in range that has recived the message and people could be in danger.

A DSC destress call should always be followed by the normal MAYDAY voice call. Not every one has or uses DSC correctly, so a voice call is a must.

If you hear a call and do not hear any response you should the relay the message as a voice call as a MAYDAY Relay.


This should all be covered in the Coast guard VHF opperators course. It is for the New Zealand Coast Guard.

DSC for distrss calls should be seen as adding addtionion information to the voice MAYDAY call. Also as it repeats it is also updating the postion so if the vessel is drifting it is easier to track.