Trying to Pick Up NAVTEX

[mfn002]

I recently acquired a Furuno NX-500 NAVTEX receiver on eBay. I haven't received it yet and was trying to check signal reception using an SDR connected to an MLA 30+ Active Loop Antenna. I was trying to monitor the transmission from New Orleans on 518 kHz (the official published frequency) since it is geographically the closest to my location but got nothing. I recall being able to get the signal several years ago using another NAVTEX receiver connected to a different antenna setup. Unfortunately, I couldn't get that receiver to decode the signal. It was a type that allowed you to listen to the signal, which, when I listened, came in VERY strong at the time. It didn't show what frequency it was receiving it on, though.

I would try decoding software, but I can't for some reason get any package to work with my SDR.

In case anyone is wondering why I got the Furuno before I checked if I could get the signal, it was because I recalled what I got with the other receiver years ago.

 

[ka3jjz]

Where is this 'official published frequency'?

I see they have a listing here, under NAVAREA IV SOUTH. They are on at specific times; 518 khz is rather like a graveyard MW station in that it has many stations on that frequency that share it.

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

and it largely agrees with

Marine Weather Broadcasts from the USCG

Are you listening at the correct times?

Which decoding software did you try? Did you have a virtual cable to route the audio to the software? Thee are MANY packages that can copy SITOR-B (SITOR-B and NAVTEX are virtually the same protocol). It does take a bit of setup to get it to work. Which SDR are you using?

Mike

 

[ka3jjz]

You might want to also try a Kiwi SDR in your neck of the woods. Remember to listen in USB and use an offset to get the correct pitch.

Mike

 

[ka3jjz]

I almost forgot to point out that loops are directional down this low- if it's not pointed in the right direction, you might not hear it at all, or very weakly

And of course, there's the possibility that NMG is off the air....Mike

 

[mfn002]

I was listening at 2100 UTC exactly, which was one of the NMG scheduled times. I got the information from weather.gov as well as the ITU website and the Klingenfuss 2023/2024 Guide to Utility Radio Stations.

As for decoding software, I tried fldigi, SORCERER and MULTIPSK with a virtual audio cable. I have a whole thread on this issue in the SDR forum.

I'll try to reposition my loop antenna, which is currently facing southeast.

As for the SDR, I am using a BlogV4 with SDR Sharp.

It appears the nearest KiwiSDR location is in Austin, which probably will have worse luck getting it then I do here.