Live NAVTEX messages

Today's messages
Map of today's messages


NAVTEX decoder (PC)
NAVTEX decoder (Java)


PC quick start guide
Java quick start guide

Technical information

SSB modulation
NAVTEX data format

Tools & resources

NAVTEX message encoder

NAVTEX Decoder PC version

Quick start guide
  1. Download, install and run the program.
  2. Connect your radio to your computer as described here.
  3. For 518kHz NAVTEX, tune your radio to 516kHz USB and the NAVTEX signal will appear at about 2kHz in the tuning window. For 425kHz NAVTEX-J tune to 423kHz USB and so on.
  4. Don't forget to register your copy of the program. This will let you upload your messages to this site and be kept informed of updates and bug fixes.
  5. Take a look at the new features list as it doubles as the instruction manual that I haven't written yet.

New features in version 2.1.2

Improved message browser GUI

Messages are now displayed by date to prevent the message list window from becoming too crowded.

Large messages can now be uploaded

A bug in version 2.1.1 prevented messages larger than about 2000 characters from being uploaded. This has now been corrected.

New features in version 2.1.1

Reliable uploading

Messages are queued in the case of network failure, then resubmitted to the server when the connection is re-established.

Improved GUI

The decoder GUI is now resizeable and the data and message log panes are also resizeable. The columns of the message log pane can be sorted by clicking on the column headings.

Improved decoding

The decoder can now recover messages from higher levels of noise.

Comprehensive logging

Received messages and raw logs of all received data are saved in a subdirectory of the main application directory called 'logs'. This will be "C:\Program Files\Frisnit\NAVTEX Decoder\logs" unless you changed the default option during the installation process. The raw log file is tab delimited so you can open it in Excel if you want to.

Minimise to tray

The app can be minimised to the system tray so it's out of your way while you do other things

New features in version 2.1.0

Automatic message upload

From version 2.1.0, the decoder can now upload messages to the online database. Now you can leave your decoder running continuously and share your messages with the world. You will also be able to view your messages on the interactive map. To enable uploading, you must enter your registration code which can be obtained here.

Multiple soundcard support

If your PC has several sound devices connected you can select which you want to use from the 'Sound source' menu.


The SmartTune option automatically locks the decoder to the NAVTEX transmission so the decoder can operate unattended and not be affected by receiver drift. Uncheck this option to prevent the decoder from auto tuning.

Strict FEC decoding

This option forces the decoder to reject characters that have been corrupted by errors. This ensures that the received messages are as error-free as possible, but can also result in very weak messages being lost. By unchecking this option the decoder will attempt to decode all characters, allowing noisy messages to be viewed. This is useful when using the decoder to try to receive very distant stations.

Invert option

The invert option will invert the sense of the received data. All binary 1's will become 0's and vice versa. This can be useful to check if you've tuned in on the wrong sideband.