VHF Ch 16 update

Ian

The NASA is odd to say the least that it has the NMEA -ve as the RED lead and use brown as NMEA +ve. Previously with the old Shipmate GPS that the Navman replaces, the NASA worked with just the brown NMEA +ve lead connected, using the common set grounds I guess as the NMEA -ves, in fact it would NOT work with the NASA -ve NMEA wire connected! I think I need to know the right incantation to say whilst simultaneously stirring eye of Navman & balls of Nasaman in liquid nitrogen...

Robin
 
Hi Robin

The only similar problem with a radio I have run into is when the NMEA data did not include a sentence in it with position/time information which was recognised. While I know you are not doing this but as an example, some older pilot computers only put out the GLL sentence which at least some DSC radios do not use. As you seem to have exhausted all the wiring options it may be worthwhile checking what sentences you are sending to the radio include what the radio needs (some ECS will let you monitor those if they are not documented in the manuals or can be done using Windows Hyperterminal @ 4,800 baud just putting the NEMA straight onto the computer's serial port data in/out).

A very remote possibility, and I seriously doubt if it is the issue, is that the cabling standard for NMEA is twisted pair with shield. At the talker the two conductors are attached as normal with the cable shield attached to the NMEA- with the NMEA- conductor. At the listener the NMEA + & - are attached as normal and the cable shield cut back and left unconnected. Many pleasure sailors (and yards too /forums/images/graemlins/mad.gif) just use unshielded cable which while not normally a problem can pick up interference affecting the equipment on the cable and also raise the ambient electronic noise in the boat adding to that affecting radio reception - especially if the cable is long.

Just on the USA not going down the DSC route - they are, and the project has been underway for some years (I think it is almost completed). For quite some years it has been illegal to put new model radios on the market in USA unless they were DSC or a model in production at the time of the coming into effect of the law but any such radios are now quite long in the tooth. I believe that they intend declaring a Sea Area A1, but stand to be corrected on that.

It is, in fact, an ITU recommendation that all countries bar the putting onto the market new non DSC model radios. However, many have not done so but it is becoming a fact as the main quality manufacturers phase out non DSC models (for example, I think that all Icom's production is now all DSC and possibly the same for Vertex/Standard Horizon). I would not (and do not) specify any new vessel with a non DSC VHF.

Hope you find the problem

Regards

John
 
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I have not extended my VHF license yet, so no mmsi number. Must get and do that.

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What does that mean? Are you supposed to have a different operators license if you have a DSC set? Or are you talking about the VHF license?

If I get this number what do I do with it?

Not Joking - really do not know what all this is about....

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Yes! You are required to have a DSC upgraded SRC if you intend to use a DSC set. Presume it's same in France as the SRC is an international requirement.

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What on earth is SRC?
 
Had many issues connecting a Navman 900 to an SX35, rerouted cables, ferrite beads all over the place blah blah blah, still a lot of white noise when plotter was on. Solved my the simple, if less aesthetic, method of shifting the VHF twig. Said twig is now right at the stern (on a davit actually). Long aerial lead is a bit of a pain but ther's no interference and the NMEA connection works fine.
 
Hi John

Thanks and welcome back!

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The only similar problem with a radio I have run into is when the NMEA data did not include a sentence in it with position/time information which was recognised. While I know you are not doing this but as an example, some older pilot computers only put out the GLL sentence which at least some DSC radios do not use. As you seem to have exhausted all the wiring options it may be worthwhile checking what sentences you are sending to the radio include what the radio needs (some ECS will let you monitor those if they are not documented in the manuals or can be done using Windows Hyperterminal @ 4,800 baud just putting the NEMA straight onto the computer's serial port data in/out).

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I think I'm ahead of you. The Navman needs to have NMEA output turned on and it's own 'Navbus' turned off, which is done. The NASA DSC requires the RMC sentence from the Navman and that too is turned on. In fact I have tried ALL the possible NMEA sentence options combinations or indeed singly that send Lat/Long (like GLL). The Navman NMEA data IS leaving the Navman as it will run the Yeoman with any or all of the sentence options and yes I have tried connecting Navman to NASA directly without the Yeoman. I'm not using any cable other than the leads supplied with the Navman and the NASA. Also in case you missed earlier posts, the NASA was running OK on the old Shipmate GPS (with RMC sentence) right up to when I disconnected it to replace it with the Navman.

One slight ray of hope. I spoke to an electronics engineer last weekend who said he thought he could remember one installation where they added a resistor in the NMEA output from a Navman to 'tone down' the NMEA signal. I also think I read that eons ago somewhere on the forum but I can't find it by searching. I also seem to remember having to do something similar mega-eons back on a Decca to repeater set up. However I have no idea what size to try or indeed where to find one so this needs further investigation and a begging trip to the local electronics people who haven't had a similar combination of VHF/GPS before so not experienced this problem.

So to recap:-

2 different Navman plotters (one 5500, one 5600) will both run Yeoman plotter OK but not run the NASA DSC. At least proves both plotters put out NMEA.

Only the old Shipmate 5800 will run the NASA, but at least proves it too CAN work.

I did a master reset of the NASA under their telephone instruction but it made no difference other than I had to re-enter the MMSI, all the other configuration choices (ie auto Lat/Long is turned on and manual off) are seemingly OK.

The 5600 Navman I took to the importer and had the latest software upgrade installed just in case, it too made no difference.

Re the general comments on DSC I was being a bit flippant but nonetheless it does seem that Europe at least has adopted the very letter of the law immediately whereas others like the USA are at best taking their time at least as far as leisure sailors are concerned since they have no stations to receive DSC distress calls yet (I believe).

Robin
 
SRC is the Short range Certificate which includes DSC and replaced the old VHF Restricted certificate. You must have either that or LRC to transmit, except under the supervision of a certificated person or for distress use.

And the answer to the question in your quote is that it's the ship's licence that is linked to the MMSI. If you keep the particulars of your equipment up to date and pay for your licence they will issue your MMSI.
 
So provided I do NOT enable my VHF for DSC I will not get arrested in UK waters?

My very very old VHF certificate will be OK?


(I have only ever passed two exams in my life - one was the VHF the other heavy goods class one! I am now heading for Brighton to get a CNVI!!!!) Sailing is becoming very hard work - I prefer KISS
 
When I first realised I had a DSC on board the new boat I telephoned the radio Communications Agency and asked if I'd be thrown inside for only having the old cert. Nice lady said "don't worry you're OK with that licence until you do the upgrade".
Anyway I did the LRC coz I also had a big black "squeaky, pop whistle & hiss" Icom SSB sat by the chart table. That covered the DSC VHF.

Ian
 
Fine Robin

Seems an interesting problem, especially as its not mine /forums/images/graemlins/smile.gif.

On the signal level and resistor bit I would have thought that if one had two listeners, the Yeoman and the radio, connected to the Navman that would be sufficient to attenuate it if that was a problem as they would be in parallel on the same Navman port (from the manual the 5600 seems to have only one NMEA port, forgetting the fuel one, ).

On the USA DSC thing, the replacement of all VHF stations was due to be completed next year and I had since my last post determined that it is USCG policy to then delare a Sea Area A1 - I did see relatively recently in a USCG news that many stations were now in operation. There is also full MF/HF DSC coverage now from operational DSC stations even though some other stations are yet to be commissioned, and it seems that they will declare Sea Areas within the coverage (A2, etc)

But you are absolutely correct, they took their time about it and have also jawboned ITU into watering down the new Class D specification published last year to be similar to the non "old" Class D radios that were already being produced for the international market.

John
 
It is NOT correct to say that ships are no longer required to maintain a listening watch on Ch16.
There was a recent International Maritime Organisation (IMO) statement which says that 'for the foreseaable future' ships "will continue to monitor 16 on the bridge to enable comunications with non-SOLAS vessels and for bridge-to-bridge communications between SOLAS vessels".
This was also all reported in ST in the May 2005 edition.
Also, Coastguard Rescue Centres will maintain a headset watch "when circumstances demand it". As said elsewhere, the CG stopped mandatory headset watch a year ago, at the watch manager's discretion.
 
I think that srm is however probably correct.

The IMO Subcommittee on Radio Communication and Search and Rescue (in Notes of the 8th Session Feb04) discussed this and "came to the conclusion that watchkeeping on VHF channel 16 by SOLAS ships should be required and kept for the foreseeable future with a view to providing a distress alerting and communication channel for non-SOLAS vessels; and bridge-to-bridge communications for SOLAS ships. It invited the {Maritime Safety} Committee to note this view."

I do not know if the Maritime Safety Committee took this any further but I have had a look through all of their circulars since the sub committee meeting and there do not seem to be any actioning the sub committee's view.

I do not work with SOLAS ships these days so would be interested to be directed to it if such an instruction exists, as it may well do. Of course, flags may have made their own instructions to vessels on their register and I am aware that some countries have requested SOLAS vessels while in their waters to maintain a watch on CH16.

I think the critical thing out of that is that I frankly would not rely on nor expect a SOLAS vessel to be listening on CH16.

John
 
Well said.

I concede that I normally do not watch CH16 unless I have some particularly special reason to do so.

John
 
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