DSC - Am I missing something ?

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Dann

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Having installed this season a new DSC VHF set, as encouraged by the CG, I have used selective calling to contact the local CG a few times for routine traffic. However, I was surprised that following the digital call, the set went back to ch 16 and I had to call the CG in the normal fashion, CG then responded requesting ch 67 to proceed with call. This seems to negate the advantage of selective calling. I would have expected to automatically be directed to 67 and called by CG on that channel, otherwise what is the point of going through the individual DSC call procedure. My set does not let me insert a channel for shore station calls. Have I missed something ?
 
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I guess when the CG come back they do not know whether you have switched to their working channel so they play safe by coming back on 16?

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no Ken. the cg have class a controllers with the ability to switch your set to their working channel when they respond and you press the button to acknowledge. so if they leave you sat on 16 they are either ignoring your call or more likely they will respond to you when they are ready to talk ie unlike normal voice calls they dont come back to you straight away to ask you to wait on 67, but instead they respond to your cvall when they are ready for you.

if in the meantime you get impatient and call up on 16, you effectively short circuit their system
 
Thanks for that "watayottie". Do the CG have a database of MMSI numbers that allow them to respond with the callers name on 67, or do you get "yacht calling xxxxCG" ?
 
only safety urgency and distress calls go back to ch 16 , routine calls even to CG go back to their working channel 67 automatically . Even if you program channel 16 when you call coastguard the set will go to the working channel of CG when they reply .
 
They can consult the the database of MMSI numbers but I think they only do it in case of distress . I once called Falmouth CG for routine and they just asked my call sign.
 
As I understand it the CG will digitally acknowledge your call (when they are able to) thereby changing your set to the desired working channel - probably 67 but it could be another Ch. if 67 is being used for distress working. You will have to accept the digital acknowledgement to continue. Accepting the call will not send back a digital reply but only change your set to the working CH.

It is then up to you to transmit to them ie,,, "xxxCG this is yyyy MMSI 23xxxxxxx." followed by why you were calling them. That way they know that the person speaking is the yacht that called them by DSC and not somebody else that has butted in.

They won't be the first to speak. Or, at least that's what a CG told me - it's a bit like ping pong.

Shorn
 
Point is that if you call another station digitally, they get to set a working frequency. Your radio automatically tunes to it & you call them there. Thus freeing up CH16 which although used as a calling channel, is actually reserved for distress & emergency working. It may just happen to also be a channel which HMCG would direct you to although it's more likely to be 67 or something else depending on where you are.

So, you can still make calls when there's a Seelance Mayday in operation.
 
This all seems to be a bit hit a miss and not well documented. The procedure was certainly not covered on the RYA DSC course I attended a few years back and I haven't found calls to coastguards covered in any of their VHF/DSC publications.
 
Gawd almighty! I knew I had made the right decision to stay wih my steam powered radio! /forums/images/graemlins/cool.gif
 
I had to fit a DSC set due to local(EEC?) rules but I still have my trusted green Sailor wich is a much better set than my Simrad RD68 anyway.I don't think I'll ever use the DSC facility as the air waves are not nearly as crowded here in the Algarve as in the UK.In order to use DSC with any degree of competence you need quite a lot a pratice wich I'm unlikely to acquire with the sort of use I get down here.
I know this is ment to free the air waves for real emergency work but it's been on for quite a while now and I never heard anything good said about it.
 
I attended the course on Sunday and it wasn't covered then. Nor in the RYA G22 booklet. It would seem its not in the RYA syllabus so not covered. I am sure I have read somewhere, I think in the information pack that I received after I registered on the CG66 scheme, that when calling the Coast Guard using DSC the set should go to Chl 16. You should then wait for a response from the Coast Guard who will quote your MMSI and instruct you to go to the working channel. I guess this does slightly reduce traffic on 16 and allows the Coast Guard to respond when free to deal without having to either note down the calling vessels name or replay their recording.
 
The chances are it was covered as ship to ship which is the same process.... the only difference is that when you call the coastguard they will have set their DSC to switch you to 67 when they acknowledge where a ship would have set their radio to switch you to a ship to ship channel like 6/8/77.

It seems different DSC radios have different menu systems to achieve the same ends and unfortunately the MCA and RYA have latched onto the SIMRAD as if it is gospel and so some things on your radio may require different button push sequences. If you read your manual you will see how you can set your radio to switch the calling station to a particular channel when you acknowledge a ship to ship call. There should allready be a channel preset here.
 
I've been using DSC for 3 years and have only good things to say about it apart from being made to jump when the alarm goes off. It's a boon in many ways - calling the CG and not being told to wait, calling other vessels, getting other vessel's positions and being able to see them on the chart plotter, etc.

What I have found, though is that each set has a slightly different way of being operated, and unless you are really au fait with your set, you can end up not knowing what to do. For eaxample, on my ICOM, when CG responds, I press the accept button once, and then again to get it to change to the CG's required frequency. If I don't press it the second time, I end up on 16 with the ensuing confusion of what's happening, and blaming the set (which I did for a month or so before reading the manual...!)

Also, you need to take care you transmit on high power and not low...as I know to my embarrassement.
 
Thank you Piers. I think you may have the answer. My set is an ICOM M505. The handbook does not mention second pressing of the acknowledge response, but next time I will try it.
 
Page 42 refers to an incoming call. However, this may well be the procedure when calling the CG where, unlike calling another ship, one cannot enter a working channel. So, when CG responds to a DSC call with and acknowledgement, if you press enter it will direct you to their selected working channel. I will give it a try.
 
I think you will find the CG numbers are different .....all start with 00, 11 ,22 ??????????
Cant remember but if you check the list out and then check out which area is on 67, 10 etc you will notice a pattern

when you dsc solent your set knows a mmsi no. starting with 00 ? or 11 will receive a call on 67 and automatically put your set on 67 which is why you do not set it.

The CG will not know who is calling him so can not reply to you by name so it is a waste of space really
 
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