Navtex Question ?

[BOBRR]

Hello,

If I leave the radio on all night with hopes of recording Navtex, what's
the best bet for how to tune:

a. a "bit" below the quoted frequency and use USB mode ? (one or two Hz below ? which ?)

b. the quoted frequency, and am ? (what filter width would be best ?)

c. or ?

Any hints and suggested would be most welcome.

Thanks,
Bob

 

[trentbob]

Hello,

If I leave the radio on all night with hopes of recording Navtex, what's
the best bet for how to tune:

a. a "bit" below the quoted frequency and use USB mode ? (one or two Hz below ? which ?)

b. the quoted frequency, and am ? (what filter width would be best ?)

c. or ?

Any hints and suggested would be most welcome.

Thanks,
Bob

I noticed that nobody's responding Bob but I remember navtext as being a weather information, maybe automated, at 518 megahertz for ships at sea?

I'd have to do some investigating on the internet, do you have Google? I'm not sure what the status of this is because it might have been in the '80s??

I think it's still mandatory for ships over a certain tonnage but my knowledge is limited and I'd rather see you researching. Try putting it in Google in in several different ways.

 

[nd5y]

NAVTEX is on 518 kHz. That's the center frequency in between the two FSK carriers. The exact frequency you need to tune to depends on what kind of receiver and decoder you are using.

 

[WB5UOM]

per google....

NAVTEX Maritime Safety Broadcasts | Navigation Center

 

[ka3jjz]

Oh there's LOTS more than that...

https://www.dxinfocentre.com/navtex.htm

Bob it would be most helpful if you would say what SDR or radio you are using and which software. Did you know that there's a reflector devoted just to 518 khz listening? Looks like a very busy place

navtexdx groups.io Group

This group is for those interested in Navtex Dxing. We monitor long distance transmissions on both the MF and HF Bands. NAVTEX transmissions are navigational and meteorological warnings and forecasts, as well as urgent marine safety information to ships, and made at either regular scheduled...

groups.io

Of course you could simply try tuning in a signal in the early evening using whatever setup you're using. You won't damage anything by mis tuning something and not decoding properly. Just sayin'....Mike

 

[BOBRR]

Hello All,

Much thanks for the thoughts and comments.
Most appreciated.

To answer some of the questions:

Have an Icom R8600 radio.
Would like to decode to a mac.
Trying with the BlackCat Navtex decoder. (are there any other "mac" Navtex decoders ?)

Another Question:

Do I want to tune the radio to the basic center frequeny, like 518 KHz, and set the
mode in the radio to FSK ? Or, ?

Wide Filter width ? e.g., ?

Thanks again.
Great hobby for my Sr. years, but can be a bit
frustrating at times.

Regards,
Bob

 

[ka3jjz]

There are 2 others that can copy SITOR-B. Note that NAVTEX is built on a SITOR-B engine so if the software copies SITOR-B it will also handle NAVTEX

https://www.w7ay.net/site/Applications/cocoaModem/index.html

MultiMode - CW RTTY SSTV FAX MORSE PSK31 ACARS SITOR AMTOR ALE DTMF FFT ASCII Decoding Software for the Macintosh

MultiMode is a sharewareware digital modes software package for the Macintosh, transmitting and receiving CW,RTTY,SITOR,FAX,SSTV,ACARS,PSK31 and more!

www.blackcatsystems.com

I don't have a R8600 but if it were me, I'd simply tune 518 khz in USB, wide filter for now, and if it doesn't work, tune down - you may need a 1.7 or 1.8 khz offset to get the right tones. It depends greatly on how the 8600 handles a FSK signal and passes the tones. It will take some experimentation to get this right.

There is a pretty active R8600 reflector on groups.io, viz

ic-r8600 groups.io Group

Icom IC-R8600 Wideband SDR Receiver This group has been created to provide information and a discussion forum for the new Icom IC-R8600 Wideband Receiver. The IC-R8600 is based on the IC-7300 SDR technology, and features a touch-screen. It covers multiple bands and modes up to 3 GHz. Spam...

groups.io

Mike

 

[Saint]

Take a look at these video's I did and see if they help you.
Saint.

Decoding Navtex Message with Multipsk Software
Multipsk decoding Navtex message
Navtex Decoding with Multipsk software 8415 KHZ USB

 

[BOBRR]

Hi,

The following list was from a Post by "Saint"quite a few years ago.

If Saint is still monitoring, or anybody else, what are they ?
They are Not Navtex, are they ?

"All these frequencies work for me down hear in Fort Erie Ontario Canada, hope they help you.
KHZ
6312000
8414000
8415500
12578000
16804500
16804000
16806000
Good Luck. Saint"

 

[Saint]

Hi,

The following list was from a Post by "Saint"quite a few years ago.

If Saint is still monitoring, or anybody else, what are they ?
They are Not Navtex, are they ?

"All these frequencies work for me down hear in Fort Erie Ontario Canada, hope they help you.
KHZ
6312000
8414000
8415500
12578000
16804500
16804000
16806000
Good Luck. Saint"

These are GMDSS, DSC frequencies that I pick up Navtex on from time to time. I can confirm I received navtex on them also.
Saint

 

[ka3jjz]

Bob I would advise sticking to one problem at a time. Use the reflectors I suggested, as they will be the best place to go for help with NAVTEX. Any reflector that is devoted to a receiver is likely to have some pretty sharp folks there.

If you do decide to go into DSC decoding there is yet another reflector devoted to that topic

dsc-list groups.io Group

*WELCOME TO THE DSC LIST:* This is a specialist group for enthusiasts of the 'DSC' Mode (Digital Selective Calling), and users of programs like 'YaDD', 'DSCdecoder' and 'Multipsk'. Membership is open to anyone with an interest in the DSC modes, but because this is a private group all...

groups.io

And of course, don't forget the Utility DXers Forum reflector, too. Lots of sources for information

Mike

 

[BOBRR]

Hi,

Lots of really very good info. for me to digest today.
Sure is a lot (for me) to learn.

Just want to sy. quick thanks to everyone.
Help and suggestions are truly most appreciated.

Thanks again, Best regards,
Bob