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-   -   500 Khz (https://www.shipsnostalgia.com/showthread.php?t=38497)

R651400 17th March 2011 08:49

500 Khz
 
500 Khz or 500 Kc/s as I better know it.
IMO have endorsed the US proposal that "5 ton" will now be part of a new navtex system operating between 495 and 505 khz.
This should be ratified at the next World Radio Conference which I understand will be early next year in Geneva.

Moulder 17th March 2011 09:32

When shall we have the wake then? (Sad)

(Thumb)

R651400 17th March 2011 12:05

A wake only if the QRG is completely dead?
I'm happy it will still continue to offer a service to mariners.

Gareth Jones 17th March 2011 16:48

Quote:

Originally Posted by R651400 (Post 499864)
A wake only if the QRG is completely dead?
I'm happy it will still continue to offer a service to mariners.

Quite right - I heard somewhere that amateurs wanted to use it - nothing against amateurs, but it didn't seem right to me.
In its day it was the most important maritime frequency and it would be denigrating to use it for chit-chat. (even though, in distant parts, some of us well may have!).

NoMoss 17th March 2011 18:35

Quote:

Originally Posted by Gareth Jones (Post 499923)
Quite right - I heard somewhere that amateurs wanted to use it - nothing against amateurs, but it didn't seem right to me.
In its day it was the most important maritime frequency and it would be denigrating to use it for chit-chat. (even though, in distant parts, some of us well may have!).

They would have kept it as a Morse frequency though.

david.hopcroft 17th March 2011 20:12

Have a look at the News News tag at

http://www.fortperchrockmarineradiomuseum.co.uk

It's all there.

David
+

Moulder 18th March 2011 16:39

Quote:

Originally Posted by NoMoss (Post 499939)
They would have kept it as a Morse frequency though.

Yes - my feelings exactly.

It is sad that the frequency, that meant so much to all of us and one that we spent hours listening to manual signals on, should be given over to a non- morse, automated printer system. (Sad)

(Thumb)

Cisco 20th March 2011 11:56

Quote:

Originally Posted by Gareth Jones (Post 499923)
In its day it was the most important maritime frequency and it would be denigrating to use it for chit-chat. (even though, in distant parts, some of us well may have!).

Mmmmmm... I don't think the amateurs have been using it for chit chat...

http://www.fortperchrockmarineradiom...k/page%207.htm

I think the amateurs on 500 have a good sense of history....

Ron Stringer 20th March 2011 13:48

Surely it is better that the frequency is retained within the maritime field for the broadcast of essential safety information than for non-safety related purposes - perhaps absorbed by the broadcasters for yet another AM music (/) channel?

The frequency spectrum is constantly under pressure from commercial and other interests and at every ITU World Administrative Radio Conference, there is immense pressure on governments to agree to a reduction in the frequence allocations for maritime use. Remember that all governments are represented there and each has one vote, even though the majority of countries have no ships at all. Of the 200-odd members, how many do you think are interested in the running of merchant ships?

R651400 21st March 2011 09:02

Somewhere else I posted that 500 khz may be chosen as an international heritage frequency for radio amateurs and I think it was Troppo who was more au fait on the situation replied it was going to be taken over by Navtex.
As a licenced amateur I would have been equally as happy for 500 to have become part of the the international radio amateur band plan.
Interest in LF radio is high and there have been temporary licences issued for 500 khz.
Exceptionally the Spanish put out a 500 khz beacon EA3WX which was heard all over Europe.
.

Troppo 21st March 2011 22:24

Problem was the amateurs were not well organised enough...

R651400 22nd March 2011 06:25

Well it's too late now Troppo but amateur v commercial and a US outfit to boot did they ever have a chance?

Troppo 22nd March 2011 06:45

No - amateurs never had a chance.

IMO was always going to claim it - as they should.

At least 5 ton will remain maritime.

Rgds

Mayday 31st March 2011 16:49

I think the best thing to do is to have a permanent silence period on 500 kHz in honour of all those seafarers who died at sea.

Just my thoughts.

John McKay (Mayday).

King Ratt 1st April 2011 10:00

That is a nice thought, Mayday.

Troppo 1st April 2011 11:04

I agree with all the sentiments expressed here, but as someone on the inside, let me tell you that NO ONE at IMO gives a stuff about the heritage value of 500.

Do not forget that IMO were the bastards who merrily presided over the demise of our profession. The much touted GMDSS is a mess. Principally because ships do not carry dedicated communicators.

Alas, 500 would have never been made a heritage freq, despite all the good work of ex-R/O's.

Sad, but true.

So, at least 500 remains as a safety freq for the maritime service.

Ron Stringer 1st April 2011 20:16

Quote:

Originally Posted by Troppo (Post 503436)
So, at least 500 remains as a safety freq for the maritime service.

Frequencies are worth big bucks these days and at every opportunity those with the money (broadcasters and cellular mobile telephone services) try to obtain a bigger share. The only protection that any of the less profitable services have is by designating frequencies for safety and distress communications. Even then they have to provide extensive evidence that the uses that the frequencies are put to cannot be achieved in any other way.

Amateurs are well down at the bottom of the heap (just) below even the lowly maritime services. So if 500 kHz had not been assigned by the ITU to a safety-related maritime service such as Navtex or DSC, it would have been re-assigned not to the amateurs but to some other service with money to spend. Remember that few of the 200 or so countries that make up the ITU (the organisation that allocates frequencies - not the IMO) have any active involvement with merchant shipping. Aeronautical comms (they all have airports and nobody wants a 747 dropping out of the sky because of lack of available navaids or safety cmms), broadcasting and cellphones are in every country so pinching lumps of frequency spectrum for those purposes gets all their votes.

Rejoice that it is still in the maritiime community and will continue to make a contribution to safety.

trotterdotpom 1st April 2011 21:38

500 khz is only remembered by a dwindling group of former Marine Radio folk which will be non-existent in about three decades max, so, realistically (not like me!), what would be the point of making a memorial of a silent frequency?

Getting into range of that 500 kcs cacaphony in the Channel was a good sign that you were nearly home, but ... what a racket!

There is already a generation of seafarers who have never sailed with an R/O, maybe I could get myself designated a "heritage site".

John T.

PS My theory is fading fast, but something tells me that 500 kcs wouldn't be much use for mobile phones.

Ron Stringer 1st April 2011 22:57

Quote:

Originally Posted by trotterdotpom (Post 503549)
PS My theory is fading fast, but something tells me that 500 kcs wouldn't be much use for mobile phones.

No, but some of the frequency bands allocated for marine radar and marine satellite communications have been targeted for some years now. The MF W/T band is a target for aerobeacons and other navaids, the MF R/T band for the broadcasters. It is only a matter of time. (Sad)

R651400 2nd April 2011 19:24

Thanks to everyone who contributed to this thread.
I think t.p's comments in #18 realistically have hit the nail on the head.
Thirty years from now I wonder how many of us will be around to tell our grand or great-grandchildren what a silence period or 500 kc/s was and more to the point will they actually be interested?
I have my doubts!

richardwakeley 3rd April 2011 07:06

I guess it's appropriate that 500kc/s should be used for Navtex. Unfortunately, it was the failure by a few R/Os to copy Safety (TTT) nav warnings after the old silence periods that led to the famous 1970s disasters when ships ran full speed into wrecks in the English Channel that led to the introduction of Navtex.
Now Navtex is an integral part of GMDSS. Of course it can also be ignored by the navigation watch officers. But I have noticed that most ships I board in the course of my job have a system for checking and filing the print-outs. They can never complain they didn't get the warnings.

trotterdotpom 3rd April 2011 08:34

"...it was the failure by a few R/Os to copy Safety (TTT) nav warnings after the old silence periods that led to the famous 1970s disasters when ships ran full speed into wrecks in the English Channel that led to the introduction of Navtex."

Huh? I never hear that one before.

As far as I'm aware, Navtex didn't come out even experimentally until about 1990, so it was a pretty slow response.

My only experience of Navtex had reems of paper being spewed out giving warnings for the Atlantic to ships in the Pacific. It all ended up in the rosie.Hope they sorted that out!

John T.

Ron Stringer 3rd April 2011 10:07

Quote:

Originally Posted by trotterdotpom (Post 503790)
"...it was the failure by a few R/Os to copy Safety (TTT) nav warnings after the old silence periods that led to the famous 1970s disasters when ships ran full speed into wrecks in the English Channel that led to the introduction of Navtex."

Huh? I never hear that one before.

Well they say that all life is a learning experience, John

Quote:

Originally Posted by trotterdotpom (Post 503790)
As far as I'm aware, Navtex didn't come out even experimentally until about 1990, so it was a pretty slow response.

Slow is the normal operating mode for international organisations such as the ITU and IMO - it is one of the downsides of democracy. If you ask a couple of hundred countries (or people) to agree on the best way to do something, it takes time before there is agreement and consensus on how to proceed.

However the Scandinavian countries (led by Sweden) had a system up and running in the late 1970s and the UK (not always an early-adopter) ran an "experimental" station at Cullercoats at the beginning of the 1980s. This was declared permanent in 1983 and the service was expanded adding stations at Portpatrick and Lands End (later moved to Niton to improve coverage).

During the 1980s, Navtex was adopted by IMO as part of the FGMDSS and the service was introduced in countries outside Western Europe. The first NAVTEX Manual was issued by IMO in 1988 (and has been reissued at intervals of 5-7 years since - it is currently in its 4th Edition) and the carriage of NAVTEX receivers was made mandatory for ships over 300 tons from 1993. Which is probably when you first came across it on FOC vessels.

Quote:

Originally Posted by trotterdotpom (Post 503790)
My only experience of Navtex had reems of paper being spewed out giving warnings for the Atlantic to ships in the Pacific. It all ended up in the rosie.Hope they sorted that out! John T.

As always the tool is only as good as its user. All the NAVTEX receivers that I encountered had a facility (demanded by the IMO and CCIR recommendations/ specifications) to exclude messages - other than distress-related messages - from any stations. So if you were in the Baltic and had no interest in broadcasts from Iceland, you simply selected Iceland as a station to be ignored. Of course if no one bothered to do that, you got a lot of unwanted bumf, especially at night when the range of 518 kHz can be significant.

Initially there were problems because many of the early stations transmitted at far higher powers than were necessary to provide the coverage area that they were serving. They were established by coast station engineers who were familiar with the power used by their morse or R/T transmitters and who did not at first appreciate that on a dedicated (interference-free) frequency using SITOR they could cover their area with low-power transmissions. Iceland was one such atation whose coastal nav warnings could be received over almost the entire North Atlantic until they could be persuaded to reduce power.

Democracy and international independence played a part too. Although IMO agreements affected what happened aboard ships, there was (is) no such vehicle for what happens at the shore end. So if, for example, Gadaffi wanted to put a station up that enabled broadcasts to be made (at any time he chose) from Libya and which could be received across the entire Med, into the Baltic and along the West African coast, there was nothing to stop him. Eventually a NAVTEX co-ordinating panel was established and by negotiation and persuasion, countries with overlapping transmissions arranged such things as transmitter powers and times of broadcasts so that they complemented each other to provide a sensible service.

But it took time and there is still no requirement that countries must provde continuous coverage along their coastlines - oh for a benign dicator on occasions.

NAVTEX was a creation of its time. When it was started in the mid-1970s, there was no maritime satellite service and no other means of putting safety information aboard ships outside the 8 hours a day that there was an R/O on watch. Today a far better equivalent is available via satellite but such resources did not exist almost 40 years ago. SITOR was available and in use at sea for commercial communications - a little lateral thinking within the Swedish PTT saw it as a means of putting safety information aboard Swedish ships (which were provided with automated radiotelex facilities - Maritex). And NAVTEX was born. Like the rest of us it may now be a little past its sell-by date but when introduced, there was nothing better available.

Had there not been so much opposition to INMARSAT from certain IMO member countries, the SafetyNET service might have replaced NAVTEX within the GMDSS. But there we go again - democracy and politics. [=P]

trotterdotpom 3rd April 2011 11:10

I came Downunder in 1980 so wasn't aware of most of that. What a good job they got it sorted out fairly soon after it was needed.

Actually, I think my comments about Navtex were in error, the warnings that came out covering unwanted areas probably came out of the Sat C. There was no way of stopping them and consequently they were largely ignored. Luckily, at that stage, I was still there to get proper navigational warnings from other humans.

I'm not sure when they got Navtex going in Australia, but I suppose they did.

John T.

Troppo 4th April 2011 03:16

Australia is an A3 Sea Area.

No MF NAVTEX.

Coastal "NAVTEX" warnings are delivered over Inmarsat C EGC.


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