DSC Correspondence with MCA

[Thistle]

[ QUOTE ]
80 dB(A) at a distance of 1 m from the equipment

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Doesn't this mean that at a distance of 0.5m from the equipment the noise level will be 320 dB(A)? And isn't 160 dB(A) enough to cause damage to hearing? And isn't it unreasonable, within the confines of a yacht, to ensure that no-one ever comes within about 0.8m of the radio? (The working position at most yacht chart tables is likely to be within this range, I'd have thought.)

It follows that, on the basis of health and safety, the situation needs to be addressed. Come on MCA: do your job and protect us from this danger!

 

[peterb]

[quote
Doesn't this mean that at a distance of 0.5m from the equipment the noise level will be 320 dB(A)?

[/ QUOTE ]

Well, no. Decibels are on a logarithmic scale, so that an extra 10 dB would mean 10 times the power, 20 dB would be 100 times, 30 dB 1000 times, and so on. If you halve the distance to the speaker then the speaker power is only going through one quarter of the area, so that the power concentration (watts per square meter) has gone up by four times. That works out at about 6 dB, giving a total loudness of 86 dB(A).

 

[Robin]

Re: My VHF. None DSC. I\'m a Luddite.

[ QUOTE ]
I am not there, but the guts of the problem seems to me that shore stations (and possibly others) are sending traffic which is not distress or urgency as category "Distress" or "Urgency" and that is what needs to be fixed. Again, not being in the EU, I am not familiar with EU sets (thank goodness ) but using the M601EU as a basis it only sounds the emergency alarm for catergory "Distress" or "Urgency", otherwise it sounds beeps (3 beeps I believe according to the manual). Maybe other sets are different and present special problems when considered against my following comments, but if so one could just avoid those sets.

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John

You may be right but I have NEVER heard a 3 beep alarm, everything is the full banshee's wail! Everything from some stations goes out with the same alarm, though Solent CG (in Jimi's instance of the 'container', which WAS a fridge or a freezer BTW but since both ARE containers who are we to argue...) only used the alarm for the first transmission, the follow up repetitions were simply advised first on Ch16 then given on their working channel. If every station was as considerate it would be a big improvement! None of us I am sure object to genuine emergency or urgency calls, but 20 minute repetitions of a notification that a deep draught vessel is in the TSS I fail to understand, there is NO depth problem so what is the need? In any event Joburg Traffic have the MMSI numbers of ALL the ships in the area, why can they not send out a group call about it, we could be up to 65mls away why the heck do they want to tell us about it? I guess they are just obeying orders.....

Robin

 

[Thistle]

Oops! Thanks for pointing out my error. Muddling logs and inverse squares again.

 

[Ships_Cat]

Re: My VHF. None DSC. I\'m a Luddite.

Robin

If some friend makes an individual call to you ( using "Routine" category) do you still get the emergency alarm? If so then you would seem to have a unfortunate set (as at least the Icom 601 seems to just give some beeps for category "Safety" or less - am relying on the manual as I don't have access to a EU 601).

Why cannot shore stations make non distress or non urgency calls the same? Is not the problem that they just categorise everything as "Urgency"?

I suspect (but stand to be corrected) that it would be a quite mission to maintain dynamic groups for Group calling just selected vessels in a geographic area.

John

 

[Robin]

Re: My VHF. None DSC. I\'m a Luddite.

John

Good point but in common with most of us over here we never call each other with DSC so I've never tried it! However all of us are hearing the same banshee wail irrespective of the set in use, so I suspect that this is a transmitter initiated rather than receiver thing. We are relaunching this week so I will try and find someone around next weekend that can give us a DSC call as a test.

I know I'm repeating myself but it isn't JUST the noise, it is also that the receiving set is hijacked and the channel switched to the one the transmitting station has chosen. Last summer several times we were cruising in Biscay and received the alarm signal, the set was switched to Ch80 (which is the working channel for Joburg Traffic in the English channel, 400mls away by sea but probably 100mls as the crow flies. Not surprisingly, we don't even hear heavy breathing on Ch80, it is way out of voice range, but Ch70 obviously was just in range of the transmission that triggered the set alarm. On two or three occasions we were listening to French CGs weather bulletins on the VHF, and in the middle of their broadcast the alarm went off and the set was hi-jacked to Ch80 (and nothing heard). By the time we have run below, silenced the alarm, realised it is yet another false alarm and switched back to the weather broadcast it is all over and we have missed it. On occasions, especially if we are staying at sea or anchoring rather than going into harbour for the night where we could get a forecast from the marina office, that is our only chance of a forecast gone, there are only 3 such per day and we may miss important information. Missing a forecast is permissable of course for a genuine emergency but not for a false alarm or even the 10th repetition of a local message to ships in the TSS!

You may well be right about the transmitting stations categorising everything they transmit as an urgency call and indeed maybe they really see them as such and just maybe they really ARE in a small local area. But some stations, Joburg is one in the central English Channel have very high aerials (mounted on high hills) and therefore can be heard over extreme ranges even without unusual propogation conditions (high atmospheric pressure seems to be one, nice summer weather). We can pick up Joburg routinely at 65ml range, often at 80ml range even on voice.

Anyway, gotta go and finish polishing the prop etc ready for launch day, yippee summer is coming and snow is forecast next week!

Robin

 

[Ships_Cat]

Re: My VHF. None DSC. I\'m a Luddite.

I would be interested in what you find with an individual call (category "Routine").

I believe that from the international standard (and it would be surprising if the EU one was different for this) you should get the emergency alarm for any call category "Distress" or "Urgency" and a different alarm for all other categories (the standard specifically requires it to be different - my own set gives 3 beeps, as does the EU Icom M601 for non-distress and non- urgency).

I understand all the bit about the DSC call grabbing the set regarding the working channel. I don't know any easy way around that for EU sets for the case, as you say, if you are listening to a weather forecast. However, my own international radio will allow ignoring of channel changing interruptions from CH 70 calls while busy on another channel (eg listening to a weather forecast) unless the interrupting CH 70 call is category "Distress" - obviously yours and, I assume, other EU sets do not.

I find it surprising that EU sets do not, apparantly, work similarly. For example, what happens if one is working a Coastguard station (maybe you are even involved in assisting in a distress situation) and you receive another call on CH 70 - does your set suddenly change channels and leave you in the lurch with your current call?

John

 

[Robin]

Re: My VHF. None DSC. I\'m a Luddite.

[ QUOTE ]
I understand all the bit about the DSC call grabbing the set regarding the working channel. I don't know any easy way around that for EU sets for the case, as you say, if you are listening to a weather forecast. However, my own international radio will allow ignoring of channel changing interruptions from CH 70 calls while busy on another channel (eg listening to a weather forecast) unless the interrupting CH 70 call is category "Distress" - obviously yours and, I assume, other EU sets do not.

I find it surprising that EU sets do not, apparantly, work similarly. For example, what happens if one is working a Coastguard station (maybe you are even involved in assisting in a distress situation) and you receive another call on CH 70 - does your set suddenly change channels and leave you in the lurch with your current call?

[/ QUOTE ]

John

I need to check but yes we have 2 ways of silencing the alarm, press 'enter' and you are hijacked to the chosen working channel or press 'end' and you are not. However in practice, the only way you know it isn't a repeat call/false alarm IS to let it change channel and listen, by this time you have missed the forecast you were listening to on the original channel. The only good point is that if actively engaged on a call you would of course be close to the set, so could silence the alarm and return to the CG channel pretty quickly. When listening to a forecast it is a bit different because you don't need to stand by the set and in fact we often turn to the channel in advance and just wait for the forecast to be broadcast, whilst listening on the cockpit speaker outside, that is when an alarm and hijack is most irritating. These forecasts are not always dead on time, they can be delayed for example by the CG being engaged in casualty working, so standing waiting by the set can get tedious!

Going back to your other point about the 'beep' alert, I'm sure you are right and our sets will be the same as yours for routine calls. I'm equally sure you are right it is the fault of the stations transmitting that they label everything urgency so we get the full treatment, but that must presumably be written in their training manuals. I'm surprised the UK CGs haven't taken this up with the French stations but apparently (from another poster) the CG doesn't hear the alarm like we do but receives it as a flash warning or similar on his computer.

Robin

 

[ShipsWoofy]

Re: My VHF. None DSC. I\'m a Luddite.

[ QUOTE ]
However in practise, the only way you know it isn't a repeat call/false alarm IS to let it change channel and listen,

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That is not strictly true, depending on your set I guess. If I have as I do the coastguard saved in my buddy list, as the alarm goes off then it shows on the screen, like when your mobile rings and the caller is in your memory.

Have you tried putting Johburgs MMSI in your memory, that way you could disregard immediately.

Just a thought.

 

[Ships_Cat]

Re: My VHF. None DSC. I\'m a Luddite.

Hi Robin

From what I hear from you and others, it would seem to me from afar, that the main problem is that coast stations such as Jobourg are designating non Urgency (ie not equivalent to "Pan Pan") and non Distress calls as category Distress or Urgency (or else are otherwise able to sound the alarm which normally only goes for those categories).

My opinion would be that if that is what is happening then that and the consequences to pleasure vessels (and it is a safety consequence that you have to pursue in my view, not an inconvenience one) is the line of argument you have to use to try and get it changed. The difficulties that is causing needs to be clearly laid out by someone(s) and a complaint laid with the UK authorities responsible for policing the radio spectrum (Ofcom, I think) and safety (MCA). They will then have to weigh up which is the most pressing need for safety - your concerns or whatever the coast stations' reasons are for believing their traffic should be categorised with the alarm. Obviously, that would be in conjunction with the relevant French authorities.

That comment after quite a bit of experience lobbying government departments for change in, probably, a much less bureaucratic environment than the EU. I also suspect that you will be on a road to nowhere trying to get the standard changed regarding the ability to disable or lower the alarm loudness as there are clear safety implications in that which will always, in my view, take precedence over complaints of inconvenience (I suspect it will also take a very long time should any formal move to changing the standard occur).

With respect to the coast stations' categorising of traffic with the alarm sounding, that is the equivalent, at least, of a Pan Pan call. Prior to their implementation of DSC did they make the same calls as now as voice Pan Pan calls ie "Pan Pan" then the message? If not, and I suspect not, then one could quite legitimately challenge as to why they think they have to do so now.

John

 

[Robin]

Re: My VHF. None DSC. I\'m a Luddite.

[ QUOTE ]
With respect to the coast stations' categorising of traffic with the alarm sounding, that is the equivalent, at least, of a Pan Pan call. Prior to their implementation of DSC did they make the same calls as now as voice Pan Pan calls ie "Pan Pan" then the message? If not, and I suspect not, then one could quite legitimately challenge as to why they think they have to do so now.


[/ QUOTE ]

John

No they didn't, it used simply to go out as an all ships call on Ch 16 with an invitation to turn to Ch80, 'for information concerning........' or for a repetition of .....

Personally I also think we are unlikely to get any changes to the set design ass you said. I also think that the only people who might possibly have a quiet word with our friends in France (and the Navy) are the MCA/Coastguards, but the lack of interest at least officially makes this unlikely as well. Maybe we should just let it go and learn to live with it, but it seems to me that a facility we have found so useful over many years, now is such a pain in the arse many of us will just turn it off. In truth there are other factors also, like the incessant radio check calls that the CG still condone despite occasional broadcasts to the contrary. We can no longer make link calls and the Coastguards that used to have locations where they could look out oif a window and give condition reports now work out of call centres and see nothing except maybe the car park. Ah well, that is progress!

Robin

 

[Robin]

Re: My VHF. None DSC. I\'m a Luddite.

Jools

That is a good idea at least for the false alarm ones (the ones where they are way out of voice range), although you still cannot avoid the dash from cockpit to chart table to hit the tit in the first instance. As a confirmed spare hull but short on ballast sailor you might not appreciate that diving down the companionway every 20 minutes whilst heeled over and driving hard upwind can become very tedious very quickly!

Robin

 

[Gunfleet]

Re: I thought I had explained that already

It could've been something on the stern and we were holding the binns back to front. Para smokes, Jimi doesn't know where he is half the time and I have to be shown how to load up one of these modern self tailing winches. In fact, now I think about it a fag packet is the most likely answer.