DSC Basics

[Rustic Charm]

Originally Posted by nigel1

If you had a Class A DSC VHF radio, it has a function to Acknowledge a DSC Distress Alert. If you used that, the DSC Alert is cancelled.

Most boaters have Class D sets, you dont get that function.

Responding to a DSC Alert by Voice on Ch 16 will not cancel the Alert (All DSC Traffic is on Ch 70).

If you hear a DSC Distress Alert, the normal procedure is to listen on Ch 16. If you do not here a response from a Coast Station, then if you are in a position to assit, then call the Distressed station on Ch 16, or, if needed, Relay the Distress message.

okay, this is becoming more useful in understanding the different sets available. I would suggest, that if 'most boaters', myself included I suspect, have Class d and class D don't get that function, then I'd like to suggest that conversation needs to identify what sets we are referring too. Because if your only referring to sets that most boaters don't have then talking about 'canceling' the distress doesn't make sense.

And as I previously pointed out, the DSC system in Australia is not yet set up with ANY coast stations. There are some voluntary listening stations that have purchased themselves DSC sets, probably the class D your referring to. The DSC system in Australia is a ship to ship emergency system.

[Rustic Charm]

Originally Posted by nigel1

Sandero, I apologise for such a poor job.

RC, this attachment may help, its taken from the Australian GMDSS site, so it must be correct

No, this was not very helpful. 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.

[nigel1]

Originally Posted by Rustic Charm

No, this was not very helpful. 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.

GMDSS information by Dunstan and Associates

[colemj]

For the purposes of this thread, and what I believe its original intent to be, we should limit discussion to just Class D recreational VHF DSC use. Let's leave HF/MF and Class A to other topics.

On our radios, the emergency DSC alarm is, well, alarming, to put it mildly, and cannot be adjusted. The calling function ring, however, can be adjusted both in volume (even turn it off completely) and the amount of time it will ring. Also, it is a more pleasant telephone ring sound rather than the klaxon warning of a distress call.

When a distress call is received, our radios automatically switch their display to one showing all the information of the ship in distress - name, nature of distress, position, time, distance, and bearing.

The receiver is presented with three options for proceeding: Accept, Pause, and Quit.

Accept switches the radio to 16. If nothing is chosen in 30 seconds, the radio automatically switches to 16.

I would like to make it very clear that pressing "Accept" on a recreational radio is a GOOD thing and should NOT be avoided. Confusing this terminology and action with Class A radios is a disservice to this thread and leads to potentially dangerous confusion.

I recommend not using the flow charts that were posted here, and believe they should be removed from this thread.

Pause temporarily pauses the auto switching to 16 so that one has a chance to copy the info or make a waypoint before continuing onto voice.

Quit exits to the working channel.

We also have a "Waypoint" button. If this is pressed, the distress ship position is saved as a waypoint and the radio is switched to Nav mode showing bearing, course, etc as a GPS would.

Of course, if the radio is connected to a plotter or computer, the distress ship shows up as a target on it too.

Mark

[Rustic Charm]

Originally Posted by colemj

For the purposes of this thread, and what I believe its original intent to be, we should limit discussion to just Class D recreational VHF DSC use. Let's leave HF/MF and Class A to other topics.

On our radios, the emergency DSC alarm is, well, alarming, to put it mildly, and cannot be adjusted. The calling function ring, however, can be adjusted both in volume (even turn it off completely) and the amount of time it will ring. Also, it is a more pleasant telephone ring sound rather than the klaxon warning of a distress call.

When a distress call is received, our radios automatically switch their display to one showing all the information of the ship in distress - name, nature of distress, position, time, distance, and bearing.

The receiver is presented with three options for proceeding: Accept, Pause, and Quit.

Accept switches the radio to 16. If nothing is chosen in 30 seconds, the radio automatically switches to 16.

I would like to make it very clear that pressing "Accept" on a recreational radio is a GOOD thing and should NOT be avoided. Confusing this terminology and action with Class A radios is a disservice to this thread and leads to potentially dangerous confusion.

I recommend not using the flow charts that were posted here, and believe they should be removed from this thread.

Pause temporarily pauses the auto switching to 16 so that one has a chance to copy the info or make a waypoint before continuing onto voice.

Quit exits to the working channel.

We also have a "Waypoint" button. If this is pressed, the distress ship position is saved as a waypoint and the radio is switched to Nav mode showing bearing, course, etc as a GPS would.

Of course, if the radio is connected to a plotter or computer, the distress ship shows up as a target on it too.

Mark

Very helpful and I concur with your thought re 'accepting' the incoming distress alert.

Why do you not like the flow charts ?

[nigel1]

I think the ICOM 423 has a similar set up.
On receipt of a DSC Distress Alert, the alarm is cancelled by hitting any of the soft keys.
The user then has three options
IGN (Ignore( That will take the set out of the DSC mode
INFO: This brings up the complete DSC Alert message
ACPT (Accept): After pushing the accept button, the radio will automatically switch to CH 16 within 10 seconds

These options also apply on receipt of a DSC Distress Relay, or a DSC Distress Acknowledgement.

[ka4wja]

Whoa There!!!


{Please understand that DSC is NOT something new!
It has been around for more than 20 years!!
Introduced in 1992, and fully implemented by 1999!
(even in Australia, where they elected to use HF-DSC to cover their waters, long ago...)}


Sandero, et al,
DSC Radios do NOT act as "repeaters"!!

DSC Radios do NOT have the capability to automatically relay any DSC message, whether "Distress" of otherwise!!!

NO consumer-grade DSC Radios (Class D VHF and Class E MF/HF) even have a manual DSC relay function!!!

Originally Posted by Sandero

So DSC VHFs which are on will act as a repeater and send the distress signal out until "answered"? What does that mean - answered?

This is a often misunderstood falsehood!!
Please understand the facts here:

-- DSC Radios do NOT act as "repeaters"!!

-- DSC Radios do NOT have the capability to automatically relay any DSC message, whether "Distress" of otherwise!!! (none of them!)

-- NO consumer-grade DSC Radios (Class D VHF and Class E MF/HF) even have a manual DSC relay function!!! {Only SOLAS-grade / commercial GMDSS "Class A VHF-DSC-FM" radios have a manual "DSC relay" function, but the ITU and IMO, long ago (c. 1999, I think?) revised the GMDSS rules, specifically recommending "radiotelephony" (Voice) for distress relay, and only using "DSC relays" if this the only means available for signaling a coast station / RCC}


All of the pertinent rules and regs are available on-line for free....

Look at the ITU-R M.493 / "Digital Selective-Calling system for use in the Maritime Mobile Service" (last updated 9/2015), and the ITU-R M.541 / "Operational procedures for the use of digital selective-calling equipment in the maritime mobile service"...

Understand the rules are based on SOLAS-Grade GMDSS Compliant vessels (using Class A VHF-DSC-FM and Class A MF/HF-DSC-SSB Radiotelephones), and NONE of our consumer grade radios are capable of some of these functions, but we CAN and should follow the rules up to our capabilities, which we can very easily do!!
(i.e. if we receive a DSC Distress Call, and it continues without acknowledgement for 5 minutes, then we should acknowledge this DSC call by VOICE on the associated VOICE frequency, NOT via DSC!!!
And, immediately notify the relevant RCC / Coast Station to our reception of a Distress call and telephony/voice acknowledgement, AND ONLY THEN acknowledge the Distress call ourselves via DSC, if directed to do so by the RCC / Coast Station.)

ITU rules:

3.3.4 Ships receiving a DSC distress alert from another ship should set watch on an associated radiotelephone distress and safety traffic frequency and acknowledge the call by radiotelephony. [Voice]

If a ship station continues to receive a DSC distress alert on an MF or VHF channel, a DSC acknowledgement should be transmitted to terminate the call only after consulting with a Rescue Coordination Centre or a Coast Station and being directed to do so.

FYI, I have personally done this procedure more than a couple times over the past few years, even when sitting at the dock here in S. Florida, and having received DSC Distress calls (on HF)....

I logged the call, maintained a watch on the associated Voice Frequency, while waiting for a DSC ACK to be sent by the RCC (which they were).

The most recent event was a ship one mile up the river in Suriname, sending out a DSC Distress call on 12577....and after the DSC ACK from NMN (USCG, in Virginia, USA), and listening to them attempt to raise the vessel on 12290khz SSB telephony (Voice) for > 5 minutes, I called NMN to acknowledge my reception of the Distress call and offer to attempt contact (which the USCG accepted).

After a few attempts by me and further attempts by the USCG, none successful, I mentioned that the exact lat/lon of the call placed it about 1/4 mile inland, slightly more than one mile up the river in Suriname.

(the USCG watch officer commented that my charts were more detailed than theirs....and that they were also assuming this was a "false alert", possibly sent by a radio tech testing the radio and not realizing he didn't connect a dummy load!)

My point here is:

The GMDSS DOES work!!

And, if you read the rules, and follow the procedures, it can work all of us!!

Now, there is a LOT more to all of this, and I will follow this posting with some more details / info....but just wanted to clear up this myth that DSC radios "relay" information on...they do NOT!!

Fair winds..

John


EDIT:
FYI, Australia elected to cover their waters (and the int'l waters they are responsible for), by designating all Sea Area A3, and using HF-DSC (and INMARSAT)....
This is a UNIQUE situation, and as such those Australian sailors should have an HF-DSC-SSB Radiotelephone, as the typical VHF-DSC-FM radio would not signal AMSA (but will signal other vessels!)
It is not that Australia "hasn't yet set-up VHF-DSC coast stations", but rather that Australia long ago elected to cover their vast expanse of coastline / coastal waters (and their other waters and int'l waters they're responsible for), using HF-DSC!!!
Which is why those sailing Australian waters / Australian yachts, have long been told to have HF-DSC-SSB Radiotelephones!!!
https://www.amsa.gov.au/search-and-r...gmdss-concept/
https://www.amsa.gov.au/forms-and-pu...dbook-2013.pdf

[ka4wja]

While I tend to agree with you here Mark, I'm wondering if a recommendation to watch some of my Youtube videos (which DO have some VHF-DSC as well as primarily focusing on HF-DSC), would be good???

Originally Posted by colemj

For the purposes of this thread, and what I believe its original intent to be, we should limit discussion to just Class D recreational VHF DSC use. Let's leave HF/MF and Class A to other topics.

My thoughts here are:
--- a better understanding of DSC is easy for some by reading the ITU docs that I referred to....but most non-tech would find a simple video to be easier to learn from...

--- Australia long ago, decided to cover their waters via HF-DSC (electing to designate all of their waters Sea Area A3), and to cover their waters, and the int'l waters they are responsible for, via HF-DSC (NOT VHF-DSC, nor MF-DSC)

--- I do have some VHF-DSC videos there...


So, again, while I agree with you that the original intent was to discuss VHF-DSC, some areas of the world and some CF members do not have VHF-DSC coast stations (but DO have HF-DSC coast stations), so perhaps watching these videos will be helpful!

https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX



And, for Sandero, other than reading the referenced ITU documents and the quotes I posted, and having a bit of faith....I'm not sure how to make you believe me, but here are the facts:
1) The USCG video that you refer to is the WORST thing for you to watch/learn from!!!
There is a wealth of false/misinformation there!!!!
PLEASE, PLEASE, PLEASE ignore it!!! Delete it from your bookmarks!!! NEVER, ever think of it again!!!
PLEASE!!!

2) As I wrote earlier, and supplied the official ITU info about, DSC Radios do NOT relay anything!!! EVER!!!!

3) Please have a look at the Youtube Videos that I referenced...
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX

Originally Posted by Sandero

I am sorry to say that those who have attempted to describe the features, functionality and use of VHF-DSC radios have done a poor job. The USGC video was much better.

It might be clearer if typical use examples were given... and what is the difference between practices of standard VHF, DSC -class A and DSC class D. There is also a high seas DSC as well to make things even more complicated or complete... take your pick.

Some quick answers for you:
--- Class A VHF-DSC-FM Radiotelephones = Expensive (>$1500 - $3000) SOLAS-Grade / GMDSS-compliant VHF radios, that nobody here owns/uses....and Mark is correct that we shouldn't be discussing them, and confusing the issues at hand!

--- Class D VHF-DSC-FM Radiotelephones = Reasonably priced ($150 - $600) consumer/recreational-boater grade VHF marine radios....

--- "DSC" is Digital Selective Calling....whether it is "VHF-DSC" or "MF/HF-DSC" (what you call "high-seas DSC), they are all part of the GMDSS (Global Maritime Distress Safety System)

--- The GMDSS (and hence "DSC") has been with us since 1992!!! That's 24 years ago....so this is not new!!

--- In addition to the Youtube playlist...which DOES have some VHF-DSC videos (if you do nothing else watch #1, 10, 13, 14, and 15...)
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX
Please have a look at this page where the GMDSS is explained better...
Marine HF-DSC-SSB, the GMDSS, "communications stool legs"
And, of course, please have a look at the "sticky" at the top of the Cruiser's Forum Marine Electronics page...
http://www.cruisersforum.com/forums/...os-141406.html
And, here is the USCG descriptions of Class A, B, D, and E...
http://www.navcen.uscg.gov/?pageName=DSCClasses
And, the USCG Distress signaling info...
http://www.navcen.uscg.gov/?pageName=cgcommsCall



I do hope this helps...

Fair winds..

John




P.S. For Rustic Charm, et al, if you wish to read all the pertinent rules/regs, as I posted above the ITU-R M.493 / "Digital Selective-Calling system for use in the Maritime Mobile Service" (last updated 9/2015), and the ITU-R M.541 / "Operational procedures for the use of digital selective-calling equipment in the maritime mobile service"....are all available on-line for free...
https://www.itu.int/dms_pubrec/itu-r...9-I!!PDF-E.pdf
http://www.gmdss.com.au/ITU%20DSC%20op%20spec.pdf


Be forewarned, these are 40-60 pages docs, and for non-tech folks have lots of droll specs and confusing sentences....but it's all there if you want it!


Best advice:
--- Understand that Australia elected to cover their waters (and the waters they are responsible for) with HF-DSC many years ago, and this system has been up and working perfectly for more than a decade and a half!!!
--- Take the quotes I posted above as gospel...
--- Watch the videos I linked to....

[colemj]

Originally Posted by Rustic Charm

Very helpful and I concur with your thought re 'accepting' the incoming distress alert.

Why do you not like the flow charts ?

The flow charts are not relevant to using the recreational VHF sets we all have and are discussing here.

They create confusion - particularly by implying that acknowledging a VHF distress call is a bad thing, and then making the usage of DSC seem very complicated.

Acknowledging a distress call on a recreational radio is a GOOD thing, and the expected behavior. It is not complicated in any way - most is automatic.

Mark

[ka4wja]

DSC is part of the GMDSS....and understanding the GMDSS is important for most sailors....and has been for more than 20 years (although some non-tech journalists have only recently decided this might be a good thing! )

It's been a while since we had a discussion of the GMDSS....
That's the Global Maritime Distress and Safety System (GMDSS), which was established in 1988 (yes that is 28 years ago)....implemented in 1992 (24 years ago)....and fully operational (and mandatory for all signatory nations and SOLAS vessels) in Jan 1999 (that's 17 years ago!!)
So, this is not something new at all!!
(and I've been actively promoting it since 2001/2002....and using it myself on my own boats for a decade and a half!!)

Remember "DSC" is part of the GMDSS....and this has been around for about 20 years for most of us (yes, even us ignorant Americans, who have had the US gov't bureaucracy dragging its feet, and even the Australians who designated their waters Sea Area A3 and elected to HF-DSC) we should all understand the GMDSS by now....yes???


In addition to all of my ramblings above, and in addition to my videos....
Perhaps reading this thread, from a year and half ago, will be helpful...
Marine HF-DSC-SSB, the GMDSS, "communications stool legs"

Here's a excerpt:

(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]}

The reason I post the above is because of the obvious misunderstanding of DSC right here in this thread...
Please take note of this info that I just posted, in order to clear-up this often misunderstood topic....

Originally Posted by ka4wja

{Please understand that DSC is NOT something new!
It has been around for more than 20 years!!
Introduced in 1992, and fully implemented by 1999!
(even in Australia, where they elected to use HF-DSC to cover their waters, long ago...)}

Sandero, et al,
DSC Radios do NOT act as "repeaters"!!

DSC Radios do NOT have the capability to automatically relay any DSC message, whether "Distress" of otherwise!!!

NO consumer-grade DSC Radios (Class D VHF and Class E MF/HF) even have a manual DSC relay function!!!


-- DSC Radios do NOT act as "repeaters"!!

-- DSC Radios do NOT have the capability to automatically relay any DSC message, whether "Distress" of otherwise!!! (none of them!)

-- NO consumer-grade DSC Radios (Class D VHF and Class E MF/HF) even have a manual DSC relay function!!! {Only SOLAS-grade / commercial GMDSS "Class A VHF-DSC-FM" radios have a manual "DSC relay" function, but the ITU and IMO, long ago (c. 1999, I think?) revised the GMDSS rules, specifically recommending "radiotelephony" (Voice) for distress relay, and only using "DSC relays" if this the only means available for signaling a coast station / RCC}


All of the pertinent rules and regs are available on-line for free....

Look at the ITU-R M.493 / "Digital Selective-Calling system for use in the Maritime Mobile Service" (last updated 9/2015), and the ITU-R M.541 / "Operational procedures for the use of digital selective-calling equipment in the maritime mobile service"...

Understand the rules are based on SOLAS-Grade GMDSS Compliant vessels (using Class A VHF-DSC-FM and Class A MF/HF-DSC-SSB Radiotelephones), and NONE of our consumer grade radios are capable of some of these functions, but we CAN and should follow the rules up to our capabilities, which we can very easily do!!
(i.e. if we receive a DSC Distress Call, and it continues without acknowledgement for 5 minutes, then we should acknowledge this DSC call by VOICE on the associated VOICE frequency, NOT via DSC!!!
And, immediately notify the relevant RCC / Coast Station to our reception of a Distress call and telephony/voice acknowledgement, AND ONLY THEN acknowledge the Distress call ourselves via DSC, if directed to do so by the RCC / Coast Station.)

My point here is:

The GMDSS DOES work!!

And, if you read the rules, and follow the procedures, it can work all of us!!

Now, there is a LOT more to all of this, and I will follow this posting with some more details / info....but just wanted to clear up this myth that DSC radios "relay" information on...they do NOT!!

Fair winds..

John


EDIT:
FYI, Australia elected to cover their waters (and the int'l waters they are responsible for), by designating all Sea Area A3, and using HF-DSC (and INMARSAT)....
This is a UNIQUE situation, and as such those Australian sailors should have an HF-DSC-SSB Radiotelephone, as the typical VHF-DSC-FM radio would not signal AMSA (but will signal other vessels!)
It is not that Australia "hasn't yet set-up VHF-DSC coast stations", but rather that Australia long ago elected to cover their vast expanse of coastline / coastal waters (and their other waters and int'l waters they're responsible for), using HF-DSC!!!
Which is why those sailing Australian waters / Australian yachts, have long been told to have HF-DSC-SSB Radiotelephones!!!
https://www.amsa.gov.au/search-and-r...gmdss-concept/
https://www.amsa.gov.au/forms-and-pu...dbook-2013.pdf

I do hope that this info here, and my postings above, and my youtube videos, and all of the other links I've referenced, etc. help you all out...

If not, or if you are confused....please let me know....(but, at least read the stuff above completely and watch the videos....first...

Fair winds..

John

[gamayun]

Originally Posted by colemj

For the purposes of this thread, and what I believe its original intent to be, we should limit discussion to just Class D recreational VHF DSC use. Let's leave HF/MF and Class A to other topics.

On our radios, the emergency DSC alarm is, well, alarming, to put it mildly, and cannot be adjusted. The calling function ring, however, can be adjusted both in volume (even turn it off completely) and the amount of time it will ring. Also, it is a more pleasant telephone ring sound rather than the klaxon warning of a distress call.

When a distress call is received, our radios automatically switch their display to one showing all the information of the ship in distress - name, nature of distress, position, time, distance, and bearing.

The receiver is presented with three options for proceeding: Accept, Pause, and Quit.

Accept switches the radio to 16. If nothing is chosen in 30 seconds, the radio automatically switches to 16.

I would like to make it very clear that pressing "Accept" on a recreational radio is a GOOD thing and should NOT be avoided. Confusing this terminology and action with Class A radios is a disservice to this thread and leads to potentially dangerous confusion.

I recommend not using the flow charts that were posted here, and believe they should be removed from this thread.

Pause temporarily pauses the auto switching to 16 so that one has a chance to copy the info or make a waypoint before continuing onto voice.

Quit exits to the working channel.

We also have a "Waypoint" button. If this is pressed, the distress ship position is saved as a waypoint and the radio is switched to Nav mode showing bearing, course, etc as a GPS would.

Of course, if the radio is connected to a plotter or computer, the distress ship shows up as a target on it too.

Mark

Thanks, Mark. This is my understanding how it works as a boater in US waters, anyway, when receiving a DSC alert. These are important points because if a DSC alert happens, I should hope people will understand what it is and how to respond. Generally another boater is going to be more immediately available than the CG -- tho very nice that CG always seems to be there when we need them!.

To take the above one step further, it is also my understanding that once you press the "quit" feature on your VHF, you cannot go back and retrieve the distressed boater's information, most importantly Lat/Long. This always seemed like a deficiency to me so maybe it has been corrected in new radios. I don't know. Also, I don't think there's anything that obligates you to become a first responder, if you can't for whatever reason, should you press "accept". It merely gives you the ability to see the nature of the distress, location, etc. I attended a "DSC training" a few years back in which CG allowed the presenter to activate the DSC feature and we could see what happens on each of our radios. I think there should be a way for racing/sailing clubs and others to do these periodically. It might be a nightmare for CG to manage, but it would go a long way toward addressing many questions and misunderstandings!!

[gamayun]

Originally Posted by ka4wja

DSC is part of the GMDSS....and understanding the GMDSS is important for most sailors....and has been for more than 20 years (although some non-tech journalists have only recently decided this might be a good thing! )

It's been a while since we had a discussion of the GMDSS....
That's the Global Maritime Distress and Safety System (GMDSS), which was established in 1988 (yes that is 28 years ago)....implemented in 1992 (24 years ago)....and fully operational (and mandatory for all signatory nations and SOLAS vessels) in Jan 1999 (that's 17 years ago!!)
So, this is not something new at all!!.....

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.

[Terra Nova]

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

[ka4wja]

gamayun,
I agree with you!!
And, this is why I made the Youtube videos!!

Originally Posted by gamayun

....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.

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, {not sure what website you're referring to} 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.{I agree...but, it was Rustic Charm that specifically asked for the references / relevant sites....and I was just answering his query}

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 do hope this helps...

Fair winds..

John

[Rustic Charm]

Woah John,

Holed up there a bit. You can post way too much and just bamboozle people with 'stuff' and that's what your post is doing.

You have reacted like you have uncovered a massive error in what we have been discussing and yet the only error I think you have emphasized is that DSC is not relayed automatically from radio to radio like a repeated which I think is true. But then I'm not sure who said it was? Did anyone say that?

Thanks for the video's. I don't have time this morning to watch them, but tonight I'll get stuck into them. I love that kind of video learning

Now, the only bit I want to comment on of the pages of stuff you copied is the following two points..

Firstly, you say DSC is not new in Australia.. Well it is new. It does not matter how old the technology is, it's still new in Australia to 'people'. It's still being sold as 'new' and modern. It's now 2016 and in 2012 I purchased my first DSC VHF knowing it was the future. But my local Chandler was not overly pushing it as 'not many people are using it'.

Again, it's got nothing to do with the technology age, it's to do with it's commonality.. Another thing that is not 'new' but is very 'new' here is AIS.. Been around for ages and yet even on CF it's spoken of as if it's a new modern life saver..


EDIT:
FYI, Australia elected to cover their waters (and the int'l waters they are responsible for), by designating all Sea Area A3, and using HF-DSC (and INMARSAT)....
This is a UNIQUE situation, and as such those Australian sailors should have an HF-DSC-SSB Radiotelephone, as the typical VHF-DSC-FM radio would not signal AMSA (but will signal other vessels!)
It is not that Australia "hasn't yet set-up VHF-DSC coast stations", but rather that Australia long ago elected to cover their vast expanse of coastline / coastal waters (and their other waters and int'l waters they're responsible for), using HF-DSC!!!
Which is why those sailing Australian waters / Australian yachts, have long been told to have HF-DSC-SSB Radiotelephones!!!
What you have described here is confirming that Australia 'hasn't set up VHF DSC coast stations' . Well AMSA say they havn't and you seem to confirm exactly that. They havn't and instead elected the unique situation of recommending vessels in the wider Australian zone have HF-DSC-SSB!