DSC Basics

[conachair]

Originally Posted by AedanC

In my part of Europe (Ireland) you program in the MMSI number yourself.

However to get one you have to have a Short Range operators license and a ships license as well.

Same in UK. It helps that we are blessed with a rare thing in having Ofcom, a licensing department which is actually good at its' job and helpful

[Dockhead]

Originally Posted by conachair

Same in UK. It helps that we are blessed with a rare thing in having Ofcom, a licensing department which is actually good at its' job and helpful

OFCOM is excellent

Very advanced, efficient, online system for keeping your licenses and ship details up to date, with very reasonable license fees.

The FCC should study how OFCOM does it -- they are about 20 years behind.

[nigel1]

As far as I can remember, the Ships Station License issued by OFCOM is free of charge, at least for UK nationals, if applied for online, but a £20 admin fee if applying with pen and paper.

I suppose that someone not bothered with applying for the license and getting an MMSI number issued could just program any 9 digit number into the radio. Like Evans, I have seen 000000000 displayed on an incoming DSC call.
However, it is illegal to have VHF radio onboard and not have the license, and I'm sure that the Coast Guard carry out spot checks against the OFCOM data base. I've been asked to confirm MMSI number and call sign when in conversation with a UK Coastguard station.

Off the topic a bit, but while I was googling for some information on this, found this little nugget on the RNLI website

VHF Radios

A VHF radio will enable you to summon help by calling the Coastguard and alerting other vessels. Up until recently this was done with a mayday call on Ch16. However, the Global Maritime Distress and Safety System (GMDSS) has changed. There is no longer a legal requirement for any ship or coast station to maintain a manual watch on Ch16. The UK Coastguard and Irish Coast Guard have ceased a dedicated Ch16 headset watch and now monitor this via a wall-mounted loudspeaker. Please check with other countries if going abroad.
Instead, commercial ships and the Coastguard now monitor a special digital channel with DSC radios. To transmit a distress message on this channel you will need a DSC

[kerrydeare]

Originally Posted by Dockhead

It hasn't caught on, even in Europe. I use it only with crew and friends. And the Coast Guard ...

I am (quite) determined to extract benefits from the DSC system, but it's not always easy. Yesterday a fellow and I were discussing same. This bloke builds and repairs some well known wooden boats in our area and has been doing so for a very long time. He is also an experienced sailor and capable cruiser. Yet it still took a bit of doing to convince him that the DSC setup is worth the trouble (perhaps my lapse, but ...).

DSC just does not appear to have taken off even though it's been available for quite some time. To an extent this may be due to the complexity of early equipment, the various "classes" of gear, the setup difficulties (most likely all of the above). Still the end benefits are substantial. I will keep on plugging because I am a hard head, but what about "Joe Boater"?

[donradcliffe]

The bottom line is that DSC could have been a useful technology, but it is not. The reason is clear from reading this thread--its too hard to understand.

We have played around with DSC on the race committee boats, and its too complicated--each radio manufacturer has a different set of menus and keystrokes. For some radios it takes as many as 8 keystrokes by two different users to send a position.

Another mistake we made was following the advice on this thread to have multiple radios on one boat with the same MMSI. We have to turn one of the radios off or acknowledge calls on both radios.

[ranger58sb]

Originally Posted by donradcliffe

The bottom line is that DSC could have been a useful technology, but it is not. The reason is clear from reading this thread--its too hard to understand.

We have played around with DSC on the race committee boats, and its too complicated--each radio manufacturer has a different set of menus and keystrokes. For some radios it takes as many as 8 keystrokes by two different users to send a position.

Another mistake we made was following the advice on this thread to have multiple radios on one boat with the same MMSI. We have to turn one of the radios off or acknowledge calls on both radios.

Wouldn't say it's NOT. Maybe, rather: it's not, for many people, especially those who choose not to fool with it.

Also, wouldn't say it's too hard -- for everyone -- to understand. For some people, maybe, but it's not rocket science. And for many, some of the details don't much matter.

I can agree various implementations can make it easier or more difficult. And installers, including owners, can further minimize value by not connecting a GPS or acquiring/inserting an MMSI. OTOH, implementation and installation issues pretty much apply to most marine electronics, not just DSC radios.

We might be semi-typical. GPS hooked to radios. Easy to send locations-specific distress calls. Don't much care about the rest; don't hardly know many folks I'd want to call via their specific MMSI. Relatively easy to send position reports (in our case) but aside from a few random All Ships calls that our radios auto-respond to... I don't know that we've ever cared about doing that.

Anyway, might be a "horse to water" issue. Users can drink as much (or as little) as they'd like. Much like the way many users often don't eke out every last capability from every other piece of electronics they've got installed...

-Chris

[RaymondR]

Originally Posted by donradcliffe

The bottom line is that DSC could have been a useful technology, but it is not. The reason is clear from reading this thread--its too hard to understand.

We have played around with DSC on the race committee boats, and its too complicated--each radio manufacturer has a different set of menus and keystrokes. For some radios it takes as many as 8 keystrokes by two different users to send a position.

Another mistake we made was following the advice on this thread to have multiple radios on one boat with the same MMSI. We have to turn one of the radios off or acknowledge calls on both radios.

I have just been through the process of deciding and purchasing a new HF radio, primarily to listen to weather forecasts, and read quiet a bit on the various threads and on a number of websites and finally gave up and just bought the lowest cost Icom HF transceiver which would do the forecast part. It is all to complicated and hard to understand, probably includes a fair bit of obsolete technology anyway and appears to include to many different approaches by the various authorities involved.

I would have liked to include the DSC capability since I do go places outside VHF range but it came with a fairly significant cost penalty and by the time I got through reviewing the information available on various websites came to the conclusion that other than the EPIRB system there appears a probability that no one would be listening anyway.

In addition, if I want to do it all legally I have to form ongoing relationships with a number of various authorities. Whilst I understand why we need regulation of the EM spectrum I can tune across the entire range of marine frequencies and not hear anything other than static and Taiwanese fisherman chattering about god knows what - it appears that there are so few people using HF on the marine frequencies to be interfered with that they could lighten up a bit on the bureaucratic load. The sky did not fall in when they removed the restrictions on use of the CB frequencies and a lot of people, truckies, farmers, volunteer organizations now use them very effectively.

WiFi and the microprocessor have created a whole new communications world. If my phone, tablet and three other computers can all talk to each other without a physical connection, and it's basically just a matter of coding software, why can't my GPS, chart plotter, navigation computer, EPIRB, mobile phone, HF radio, fixed and handheld VHF's etc. not do so to transmit vital information in a marine emergency?

The whole GMDSS system needs a review and revamp in light of modern technology and they probably need to take the M out of it whilst doing so.

[transmitterdan]

Someone is always listening to HF DSC alert messages. In fact, many someone's are listening. DSC is a digital system and only requires that another HF receiver be turned on to capture DSC alert messages from another ship in distress. It does not require a human to listen intently for an SOS call. It only requires a human to alert the authorities if a distress messages is logged. So if you decided on the basis that no one is listening then that is unfortunately wrong information.

[ka4wja]

Don, Raymond, et al,
I had sort of forgotten about this thread, so thanks for bringing it back to the tops of our minds!!

I do have some easy-to-understand info for everyone....but first could I add a few brief comments/facts, that should help!!

a) DSC (whether VHF-DSC or MF/HF-DSC) is sort of like "text messaging", except it doesn't use any external infrastructure (no mobile phone towers, nor internet needed!), just your radio and anyone else's radio...

b) Maritime DSC has much greater range than your cell phones / mobile devices...(VHF-DSC has a slightly greater range that Marine VHF-FM Voice, typically 30 - 40 miles 24/7/365, for ship-to-ship, and up to 75-100 miles ship-to-shore....and HF-DSC has worldwide range)

c) You the user, can use your DSC Radios to send these "text messages" to either: all other vessels, a specific group, or just one individual vessel...

d) These DSC text messages are limited to just 5 simple messages...
1 --- A "test" message (just confirming that your radio's DSC systems are working.

2 --- A "routine" message (just as it sounds, just a friendly, routine greeting)

3 --- A "Safety" message ("Sécurité")

4 --- An "Urgency" message ("Pan Pan")

5 --- A "Distress" message ("Mayday")


e) Maritime DSC, both VHF-DSC and MF/HF-DSC have been with us since 1992, and mandatory for all SOLAS vessels and all signatory nations, since Jan 1999...
{take note that in the mid-1990's, Australia elected to use ONLY HF-DSC (and INMARSAT) to cover all of their waters (including all the int'l waters they have responsibility for), due to their vast undeveloped coastline...hence they are the only GMDSS signatory nation that didn't implement VHF-DSC into their "coastal" GMDSS plan...but VHF-DSC radios will still signal other vessels in range, no matter whose waters you're sailing in!}

f) The DSC "Distress" signaling functions are the same for ALL DSC radios...
ALL VHF-DSC radios and ALL MF/HF-DSC radios need the same "push 'n hold, for a few seconds" of the Red Distress Button, to send out a DSC Distress Alert!!

ALL VHF-DSC radios send out their DSC Distress messages the same way...

ALL MF/HF-DSC radios send out their DSC Distress messages the same way...

There aren't any variations, between different manufacturers / models of radios, in how DSC Distress messaging is done...


g) The unfortunate stupidity of letting the economic clout of the consumer marine electronics manufactures sway regulators (especially the US FCC and USCG), allowed the dreaded RTCM standard/class radios to be sold....and with them, no real standardization....

But, Now even with worldwide acceptance of "Class D" VHF-DSC radios, there are still a few operational differences in how you would send a "routine" call or "group" call...
And, while this is unfortunate....the good news is two-fold...
--- Most sailors will never use these "routine" or "group" features...
--- Icom and Standard Horizon have good user interfaces and are easy-to-use....and as luck would have it, make up a significant percentage of VHF-DSC radios on "offshore cruising boats"...


I think I hit the high points of what DSC ism what it does, and why it shouldn't be too hard to understand / use...
BUT....
No more mumbo-jumbo!!
How about some simple, easy-to-understand videos, design to help the layperson sailor???

Please have a look at these two Youtube playlists...one specifically about VHF-DSC and one generally about HF-DSC, but that describes the entire maritime DSC system...

Here ya' go...

VHF-DSC
https://www.youtube.com/playlist?lis...J6QugtO2epizxF


HF-DSC (including, LIVE real-world use) / overall maritime DSC system
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX


Please watch these videos and tell me if I made it easy-to-understand...
Thanks!!!

Originally Posted by donradcliffe

The bottom line is that DSC could have been a useful technology, but it is not. The reason is clear from reading this thread--its too hard to understand.
Please watch these videos and tell me if it's easier-to-understand now...

We have played around with DSC on the race committee boats, and its too complicated--each radio manufacturer has a different set of menus and keystrokes. For some radios it takes as many as 8 keystrokes by two different users to send a position.
Unfortunately, this has been a problem....lack of "feature standardization"....but if you use the same two brands (Icom and SH, all is usually good!)

Now, this thread was about VHF-DSC...and it sorta drifted (and, I did my share of it!
So, here again, is some brief clarification..

Raymond, unfortunately you have gotten some bad info there...
The MF/HF-DSC frequencies ARE monitored 24/7/365, by MANY stations worldwide...
> 450 MF-DSC Coast Stations...
> 80 HF-DSC Coast Stations...
~ 1000's of SOLAS vessels worldwide...

There is, of course, nothing wrong with your choice of marine radio...an Icom M-700Pro (or M-710) is a fine radio...
Just wanted to clarify that while the HF-DSC is misunderstood by some, the fact is that the MF/HF-DSC network IS monitored worldwide by many, many stations...

These facts are unfortunately not talked about much...
But, they are facts, and they are easily found on the various official sites (ITU, IMO, JComm, GMDSS, etc..)....but these are designed and written for professional mariners and "tech folks", so all too often layperson sailors are just overwhelmed!!

Originally Posted by RaymondR

I have just been through the process of deciding and purchasing a new HF radio, primarily to listen to weather forecasts, and read quiet a bit on the various threads and on a number of websites and finally gave up
Sorry about that....
If you have any input FOR me, that might help others better understand this, please let me know!

and just bought the lowest cost Icom HF transceiver which would do the forecast part.
Although just about any inexpensive HF receiver will get you the weather....an Icom Marine HF transceiver is a great choice!

It is all to complicated and hard to understand,
Again, sorry about that....
If you have any input FOR me, that might help others better understand this, please let me know!

probably includes a fair bit of obsolete technology anyway
Actually the "technology" is not obsolete at all...DSC uses similar digital communications protocols that PACTOR, etc. use....
And, while PACTOR is "newer", fact is that the FSK that HF-DSC uses, is not only the most mature and robust mode of automatic radio-teletype, it is how all PACTOR connections are initially established!!
DSC is not obsolete technology at all!!


and appears to include to many different approaches by the various authorities involved.
The only "authority" that took any different approach (if you could call it that), was Australia....everyone else is the same!
And, the only difference that Australia did was simply electing to cover ALL of their waters (and all the int'l waters that they're responsible for), with HF-DSC....and NOT VHF-DSC (nor MF-DSC)....
Australia did this back in the mid-1990's, 20 years ago....it was widely publicized and accepted...
(and this is actually a VERY important reason TO have HF-DSC on-board for those crossing the Pacific, SE Asia, etc., rather than a reason to "give up" on HF-DSC!!!)



I would have liked to include the DSC capability since I do go places outside VHF range but it came with a fairly significant cost penalty and by the time I got through reviewing the information available on various websites came to the conclusion that other than the EPIRB system there appears a probability that no one would be listening anyway.
A MF/HF-DSC radio (such as the Icom M-802) will cost you approx. $1000 more than a comparable non-DSC HF Marine radio!!
And, yes $1000 is a lot of money to most people!!

But, the facts are that are 1000's of people / stations listening 24/7/365, worldwide!! On MF/HF-DSC, not on Marine SSB Voice!!!

It appears that some have turned the info backwards....it is Marine SSB Voice where there are few listening (other than the USCG, AMSA, and NZ maritime, NOBODY else is maintaining a radio watch on Marine SSB Voice channels....
But, there are 1000's of stations that ARE constantly monitoring Marine MF/HF-DSC channels!!)


In addition, if I want to do it all legally I have to form ongoing relationships with a number of various authorities.
All you need is the SAME ships license and operators license that you need for ANY marine radio installation / use that will be used internationally!! (or any HF marine installation at all!)
That's just one ships license and one operators license....

(in the US the operators license is good for life, and the ship's license renews every 10 years, at a cost of $210....)

There are NO other authorities that you have to deal with....and the DSC system is one that operates WITHOUT the need for lots of infrastructure!

Whilst I understand why we need regulation of the EM spectrum I can tune across the entire range of marine frequencies and not hear anything other than static and Taiwanese fisherman chattering about god knows what - it appears that there are so few people using HF on the marine frequencies to be interfered with that they could lighten up a bit on the bureaucratic load. The sky did not fall in when they removed the restrictions on use of the CB frequencies and a lot of people, truckies, farmers, volunteer organizations now use them very effectively.
I won't argue legalities, but fact is a LOT of the HF comms users these days are not voice, and their signals sound a lot like noise / static!
And, if some wish to use "whatever frequency they want", please don't! I hear this a lot...and don't understand it....there is PLENTY of space for everyone, so use the channels allocated for you, and you'll be fine!! I promise!!


WiFi and the microprocessor have created a whole new communications world. If my phone, tablet and three other computers can all talk to each other without a physical connection, and it's basically just a matter of coding software, why can't my GPS, chart plotter, navigation computer, EPIRB, mobile phone, HF radio, fixed and handheld VHF's etc. not do so to transmit vital information in a marine emergency?
Most of these "consumer electronics" use infrastructure that is not available at sea....and even if they are capable of "networking together", the robustness isn't considered good enough for safety / distress systems....(they might be as food, but the rules are the rules, ya' know!

The whole GMDSS system needs a review and revamp in light of modern technology and they probably need to take the M out of it whilst doing so.
I agree with you here!!!
The GMDSS is a horse designed by committee....but, whatever revamp will just be a newer horse designed by committee!

Please don't take offense to anything I write above...
And, PLEASE if you watch the videos, let me know here what else I can do to simplify the explanations!


Fair winds.

John

[kerrydeare]

As above, it seems that the later generation of DSC VHF devices have at least tried to simplify operation. My impression, of course.

I have an older Standard DSC device and also a more recent Standard Class D DSC handheld. The difference in operation is quite clear, particularly when the software associated with the handheld is used. I do not imply that the procedures are immediately apparent or do not require some study. However there is a clear improvement in ease of use.

These devices often appear on yachts with the financial resources to acquire them. These same vessels often use services with higher than average rates. Perhaps if these providers (marinas. boatyards, fuel docks, etc.) stepped up and promoted their own MMSI and DSC capabilities, the use of DSC would be more widespread.

Just a thought.

[Timd_chapman]

John thanks for the excellent videos, it's reminded me a lot of what we learnt when i did my long range radio course in the UK. I'm currently preparing for a Pacific crossing and getting the HF radio up to speed is part of the preparations. I'm completely re-doing the antenna system but that's not for this thread.
I would like as much as possible to keep a 24/7 DSC watch on my Icom 801; my question is this: when the radio is on 'standby' i.e. turned off with no display at the control head but on at the transceiver is the radio still scanning the distress DSC channels using the DSC receive antenna or does it have to be actually turned on at the head with the display active.
I am referring here to the background DSC distress scan, not the DSC watch mode that can be activated.
Thanks in advance. Tim


Sent from my iPad using Cruisers Sailing Forum

[ka4wja]

Tim,
No, when the radio is off (in "standby") the radio is NOT doing anything, no receiving of anything...
Sorry...
It actually has to be turned on...

And, I'm not sure about the M-801, but the current draw of the M-802, in receive mode (monitoring the six GNMDSS DSC freqs, in the background) is about 2.1amps at 13vdc, with no volume / squelched....and about 2.2amps with bright display and listening to some Voice traffic...



And, please check out my new thread....
http://www.cruisersforum.com/forums/...on-169164.html

fair winds...

John

[RaymondR]

John, the emotional load one takes on when one becomes offended lost any charm it may have had when I passed 60 so I gave it up then.

The point I was trying to make was that for the very limited use I would make of the GMDSS HF system (2 ea 3 day periods in 16 years) and all the licensing and registration efforts I would have to make and cost I would have to bear and nervous energy expenditure required to implement and maintain a full legal HF GMDSS system on my boat could not be justified.

In Australia, with a population about the same as New York State we have eight legal jurisdictions with a spoon in the soup of the regulation of marine leisure activities, whilst there is a fair bit of commonality between them there are some fairly significant differences. According to their regulations if I stay anymore than 90 days in their jurisdiction I should transfer my vessel registration, drivers and marine operators license. Also, according to their regulations every time I change my address I should submit a change of address form. To make life easier for their bureaucrats (and maximize their revenue flows) most of them have changed their laws so that if they merely post a notification of any sort it is deemed to have been served and if I don't respond I may have an arrest warrant served against me. Since each of these jurisdictions has it's own parliament with our representatives madly passing bills into law just keeping current with the regulations is quiet a task for a coastal cruiser. If I appear to have become a little paranoid about dealing with bureaucrats it's with good cause.

My point about little used marine frequencies was that with the advent of satcoms much of the traffic which formerly utilized these frequencies has gone to other places in the RF spectrum and consequently they could lighten up on the licensing and station registration requirements - the radio transmission world did not come to an end when CB eventuated, it just got a little more diverse. Since there is now plenty of unused spectrum available in the HF bands they could designate some of them for citizens band use without causing any problems.

Regarding technological obsolescence. With the reduction in low earth launch costs and the proliferation and expansion of digital communications the cost of world wide readily available communications, which is already with us, will get cheaper. The costs to ship a GPS module almost exceed the unit costs. The Iridium Go unit can connect with a number of other devices for speech and data communications via satelite. Facebook and Twitter can broadcast to a multitude of subscribers simultaneously. The personnel devices required to implement a system with todays technology are already in widespread use. A reliable and ubiquitous Mobile Safety and Distress System with global reach is available to be exploited. Everything else is obsolete it just has not laid down and died yet.

Whilst I was aware that the subject HF and EPIRB distress and safety systems existed I had never taken the trouble to explore their nut and bolts and have learned a lot from a number of the threads in the forum. I certainly appreciate the effort that you and others have put into bringing the details of these systems to our attention.

[Paul L]

Originally Posted by Timd_chapman

......,o of completely re-doing the antenna system but that's not for this thread.
I would like as much as possible to keep a 24/7 DSC watch on my Icom 801; ...

You'd be about the only cruiser out there doing this. There is very little value to monitoring HF DSC on a cruising boat. No one is going to casually call you this way.

[Blue Crab]

Originally Posted by Paul L

You'd be about the only cruiser out there doing this. There is very little value to monitoring HF DSC on a cruising boat. No one is going to casually call you this way.

Surprised to hear this. I have to monitor ch16 twice a week at a marina on the ICW, and I'd guess half the hails are between buddy boaters just chatting each other up ... aka ... wasting time while the rest of us are working. I was thinking DSC could solve this ******** problem.