Navtex stations - database problems

That's a pity. I've got a support question in with ICS: I'll add to that the question of picking up messages from stations not in the database & see what they say. If it doesn't in fact matter, then there's no problem. I'll post a reply here when I get an answer.
 
alanwilson said:
No, programming in the stations data doesn't just label the messages by station name: as I understand it, it tells the Navtex what stations to listen for and when, depending on the current GPS position, the positions of the stations programmed and their ranges. So it will filter out messages from stations that it knows you are not in range of. That is to stop messages that happen to be received (by good atmospheric conditions) from far afield. Can anyone confirm whether this is definitely the case?
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I think it's a combination of your understanding and mine :)

There's no setting for station schedules, and all are on the same frequency, so I believe it will receive and store all messages for which the actual radio waves arrive. There is then a filtering system for which ones it will actually show - I have this set to a manual selection (so I went down the list and ticked Niton and a couple of others) but you're right that it can automatically change the selection based on where you are, for which it will need to know the station locations and ranges.

It has a separate screen for defining "When I receive Station X, which name should I associate with it?" - for each letter you choose between the different stations in the database sharing that letter. For most of them I just picked the Metarea I one, but for Station A I chose Corsen in Metarea II as it's closer. I think this again can be manual or GPS-driven.

Pete
 
That seems reasonable: because of the problems with finding authoritative station data, I'd like to be sure that it will receive anything within actual range (not programmed range) and display all stations: that would cope with any errors in the unit's station database. I'll be going from E coast UK to Orkneys, Shetlands, Faroes, Iceland & Greenland this summer, so it's really important to get all the weather info available (no Internet most of the time & none of this expensive satphone stuff!). When I get a definitive answer from ICS I'll post it here.
 
alanwilson said:
Unfortunately weather.gmdss.org lists only 512, not 490; only lists a few of area 4 512, and introduces a further 15 differences between it and other lists (names different, positions different, stations extra or missing and even one that is in a different area altogether to the other lists); it also doesn't show ranges, which are essential for programming the receiver.
Between 3 websites (all of which look authoritative) and a report from the Navtex Panel, I now have a total of 77 differences, just in areas 1, 2 & 4. This is ridiculous! Surely there must be a definitely definitive correct list somewhere, without having to buy ALRS (which, being a paper book, may be out of date as soon as it's published).
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Maybe adding to the confusion (?), anyway, the following link is the official US equivalent of the UK ALRS. All documents from that site are regularly updated.


http://msi.nga.mil/MSISiteContent/StaticFiles/NAV_PUBS/RNA/117chapter3.pdf

regards
 
Excellent!!! That's exactly what I was looking for. I'll compare that list with the other 3 when I have a moment. I note that the full publication is corrected to NM 25 of 2012: no date given, but it can't be more than a year out of date.
Many thanks for that link.
I do like the way the Americans decide that once the taxpayer has paid for a service, eg weather forecasts or nav aids, in their taxes, they then shouldn't have to pay again to get the data.
 
Spoke too soon: that site (US equivalent of ALRS) has less than half the actual number of 490 stations in area 1 and the list of 518 stations introduces yet more differences between it and the other sites. I need to buy a wig, then I could tear my hair out.
 
I mentioned educated guesses above - some of them were educated by looking at actual transmissions collected by a navtex enthusiast's site (can't remember the name now, but it was linked from Frank Singleton's navtex pages). That helped me decide which version of the various lists was correct - if a station had recently broadcasted about gales in the Channel, it was unlikely to be based in Murmansk or the Canary Islands.

Based on my understanding of how the Nav6+ works, if you define a preset with everything manual and everything turned on, it will show you everything it receives. I have one set up like this for curiosity about what's out there, though I wouldn't have it active for normal use. Haven't actually used it yet, as I currently only have the display box (for use as an NMEA repeater), not the decoder one :)

Pete
 
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nigelmercier said:
Does the Nav6+ have an output that you could feed into an external decoder then, such as on a PC?
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No, the decoder feeds into the Nav6+ display. The original design had the antenna and decoder in a funny-shaped curvy fin designed to mount on a rail. There were problems with leaks and destroyed circuit boards reported with those, though, and the current solution has a separate dumb aerial and a below-decks decoder box, the pair of which look like the original fin unit from the point of view of the display.

A forumite recently offered just the display unit for sale, I bought it to use initially as an NMEA repeater, which it's very good at, rather than debug my non-working YAPP display. It's not going to waste though, as I have every intention of buying the decoder box and aerial before next season, and using it as a navtex as well. By getting the screen now, I can lay out my new chart table design without having to leave an odd gap, too.

Pete
 
alanwilson said:
If you get a reply from the ITU, let me know...
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Probably not what you were hoping for, published in 2011...

Please be advised that the latest information is published by the IMO in Annex 7 to their "MASTER PLAN OF SHORE-BASED FACILITIES FOR THE GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM (GMDSS MASTER PLAN)": http://www.imo.org/blast/blastDataHelper.asp?data_id=30623&filename=13.pdf

Please note that this information is also published in the booklet of the ITU Service Publication “List of Coast Stations and Special Service Stations” (List IV), as stipulated in ITU-R Resolution 339.

Regards
_________________
Mr. A. Mohan DAS
Radiocommunication Bureau
International Telecommunication Union (ITU)

I have now emailed the IMO as follows:

Do you have a more up-to-date list of Navtex stations and their schedules than the document linked below? It appears to be two years out of date.
 
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nigelmercier said:
I have now emailed the IMO as follows:

Do you have a more up-to-date list of Navtex stations and their schedules than the document linked below? It appears to be two years out of date.
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Their reply:

Dear Sir,
Please find attached the latest version of Circular GMDSS 1 (v. 14), which also can be found on the IMO website, on IMODOCS:
http://docs.imo.org/Category.aspx?cid=133
I stay at your disposal for further details if needed.
Best regards.

Olivier Busson

Unfortunately, even after registering to gain access, the latest version was not there. I assume this is an oversight, so I have asked permission to upload a copy of the attachment here: http://www.dolcetto.org.uk/download...y System (Gmdss Mast... (Secretariat) (1).pdf
 
Nigel
thanks for that: I've just replied to an email from Olivier Busson of the IMO, sending him details of the different "authorities" and the (now 77) differences between them in areas 1, 2 & 4. I'll post what he says.
Alan
 
Olivier Busson of the IMO has been kind enough to send me the latest GMDSS Masterplan, which includes full details of all Navtex stations. I have added these to a comparison table showing the IMO data and the data on the ICS, DX and NGA websites: appallingly, overall only 10% of the stations show correct data across all the sites; ie 90% of stations are incorrect on at least one site! Most differences are minor (a few degrees out in position, although why there should be any doubt where a station is baffles me, unless it is on an iceberg), but major differences include two stations having their ID letters transposed, longitude being shown as E instead of W or vice versa and one station shown in locations 1824NM apart!

I've tried but failed to upload my data comparison document to this forum, so anyone interested in comparing Navtex station data in areas 1, 2 & 4 (my areas of sailing this summer) can email me at alwil42 at gmail.com for a copy. It includes statistics on the correctness of the four sources of data.

I also asked the UK Hydrographic Office for sources of official data: they have not had the courtesy to reply.

I'm also still trying to get definitive information from ICS (the manufacturer of my Navtex receiver) as to what happens when the station database information in the receiver is incorrect: when I get any more information I'll post it here.

Alan Wilson
 
ICS have responded: they are taking the data discrepancy very seriously and investigating with ALRS and IMO: they will keep me posted. The vital question of what happens if the internal station database in an ICS Navtex receiver is incorrect is being addressed: when I find the answer I'll post it here.
 
alanwilson said:
Spoke too soon: that site (US equivalent of ALRS) has less than half the actual number of 490 stations in area 1 and the list of 518 stations introduces yet more differences between it and the other sites. I need to buy a wig, then I could tear my hair out.
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You may have to buy a big big wig as it would appear that ALRS is the accepted Oracle on this matter with other administrations trying to play catchup. Unfortunately we are expected to pay to access :)
 
alanwilson said:
I've tried but failed to upload my data comparison document to this forum, so anyone interested in comparing Navtex station data in areas 1, 2 & 4 (my areas of sailing this summer) can email me at alwil42 at gmail.com for a copy...
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Email sent. Would you like me to upload it somewhere for you?

The forum limits for attachments are pitiful.
 
But as I understand it, ALRS gets its data from the Navtex subcommittee of the IMO, so actually IMO should be the oracle. However, the IMO gets its information from the countries that are responsible for Navtex in their areas: if they are slow in forwarding changes to IMO, then the IMO data may be out of date. Meanwhile, countries may promulgate changes locally (eg via NMs), so their own published data may actually be more correct than the official IMO data. All good fun.
 
alanwilson said:
Olivier Busson of the IMO has been kind enough to send me the latest GMDSS Masterplan, which includes full details of all Navtex stations. I have added these to a comparison table showing the IMO data and the data on the ICS, DX and NGA websites: appallingly, overall only 10% of the stations show correct data across all the sites; ie 90% of stations are incorrect on at least one site! Most differences are minor (a few degrees out in position, although why there should be any doubt where a station is baffles me, unless it is on an iceberg), but major differences include two stations having their ID letters transposed, longitude being shown as E instead of W or vice versa and one station shown in locations 1824NM apart!

I've tried but failed to upload my data comparison document to this forum, so anyone interested in comparing Navtex station data in areas 1, 2 & 4 (my areas of sailing this summer) can email me at alwil42 at gmail.com for a copy. It includes statistics on the correctness of the four sources of data.

I also asked the UK Hydrographic Office for sources of official data: they have not had the courtesy to reply.

I'm also still trying to get definitive information from ICS (the manufacturer of my Navtex receiver) as to what happens when the station database information in the receiver is incorrect: when I get any more information I'll post it here.

Alan Wilson
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Circular 14 Masterplan is the latest updated version of the list and it appears that it is from this Masterplan that other Authorities derive their versions. This latest Circular is fresh of the press so many of the other data bases you have visited may be based on lists drawn up one or more years ago.

Thanks to you pointing out this situation it has been discussed elsewhere and a few overseas authorities seem to be taking action to improve the
accuracy of their lists. The USCG should be replacing circular 13 with circular 14 soon at this web address.

http://www.navcen.uscg.gov/?pageName=gmdssReference

I would think ICS can provide Firmeware updates as their installed data bases will inherently become inaccurate over time and so affect
the reliability of the auto station selection by GPS.
 
Bilgediver said:
I would think ICS can provide Firmeware updates as their installed data bases will inherently become inaccurate over time and so affect the reliability of the auto station selection by GPS.
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I don't know about a firmware update, but there is the facility to manually edit the database - that's where we started :)

Pete
 
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