navtex reception question

[roam]

i am having probs with navtex reception.
i am currently in la rochelle and since we have left UK i can clearly get UK and NL broadcasts on 518, but get rubbish from the french Cross Corsen station which the navtex won't save. most of the time i even get the firing info (j messages), but never the weather (E), which is my primary concern! i have tried moving the aerial, but getting no better results.
any suggestions out there?

thanks

 

[davidbains]

If you can receive UK and NL then it's probably a reception problem
with the CROSS just in you present location.
It may work at sea!!
We have the same trouble in the Ionian with the Corfu transmitter. Can receive
Split and the Aegean but not the nearest one!!
In fact last year in the Adriatic I used RTTY on a Nasa Weatherman.
It gives a longer outlook.

 

[david_bagshaw]

I donrt know if this helps but on the nasa navetex we have the stainless corrodes in the bronze holder & both need a good scrape every other year.

 

[charles_reed]

You'll find navtex reception frequently deteriorates in harbour, but improves once you're at sea.

If in la Rochelle there is always an up to date forecast at les Minimes capitainerie, or invest in a Weatherman.

 

[affinite]

Ive just got back from taking my boat to Greece.
I also found trouble picking up some stations on my Clipper Navtext but discovered that moving my kedge anchor (Strapped to the pushpit rail) seemed to improve reception.
Having said that although Im based just 70 miles from Corfu, I get fewer errors from the transmission from Israel than I do from Corfu !!

 

[davidbains]

Corfu is a very poor station. It was instrumental in persuading me to get RTTY
a Nasa Weatherman. However now we're up at Trieste. My old Nasa navtex
died last year. I ordered a Furuno navtex from Cactus at 4.00pm yesterday
and it arrived at 10.30am today!!

 

[Oldhand]

Corsen weather transmissions were recieved fine in Brittany on our ICS Nav6A over the last few weeks and is usaully fine from the Solent as well.

Difficult to understand why you can receive the "J" messages and not the "E" messages other than to say you could have locally generated interference on the boat. In my tests, just about anything with a microproccessor will cause a degree of EMI at Navtex frequencies, try switching everything else off on the boat to see if makes any difference - if you haven't already done that. Fridges also cause a lot of EMI but unless its running all the time you would be rather unlucky to have it running for all "E" messages and not for "J" messages! EMI is more likely to be a problem if the received signal strength is already weak, which could be the case in your location.

 

[MedMan]

You don't say what type of Navtex receiver you have. If you have a paper print-out model there is an issue that can prevent you receiving some messages.

To enable you to read the messages whilst the paper is still on the machine, print-out models print out the last line first followed by the penultimate line etc and finally the first line. To do that they must commit the entire message to memory before they can start printing. Before they will print out a message the following
conditions must be satisfied:

1. The Message must start with ZCZC
2. The Transmitter Code must match the user-selected list of Transmitters
3. The Message Code must match the user-selected list of Messages or be
an emergency message that cannot be deselected.
4. The message must end with NNNN

It is the fourth condition that can cause the trouble. If the
forecast over-runs its time allocation and an adjacent station starts
transmitting over it, the NNNN can be lost. On my print-out machine,
that means I get nothing.

By contrast, some Navtex machines with screens appear to only require
conditions 1-3 to be satisfied and they will start to display the
information in real time as it comes in. Moored next to a friend with
such a machine he often received messages when I did not with his
messages clearly showing *45$& and other such goggledy gook just before
the end. Two minutes later I could receive a different type of message
from the same transmitter showing that it was not an installation
problem. The specific problem I have had this year is an over-run of the Iraklion
weather being over-transmitted by one of the Turkish transmitters -
Izmir I think.

From time to time I received what my Navtex believed was a single message starting with ZCZC and ending with NNNN. In fact, it was the start of the Iraklion forecast cut into by the Turkish forecast and ending with its NNNN. Provided the *&%$ goggledy gook destroys the new message headers my machine treats the two messages as one and prints it out but if it detects a ZCZC it discards
all previous information from memory and starts again.

This may not apply to you at all, but it may explain some of the problems experienced by owners of print-out machines.