Black Cat GMDSS-DSC

A full featured program that decodes and displays Global Maritime Distress and Safety System (GMDSS) / Digital selective calling (DSC) transmissions, available for macOS and Windows.

Tune your HF / shortwave radio or SDR to a GMDSS/DSC frequency and feed the audio into your computer's sound card input, and start receiving and displaying GMDSS/DSC transmissions in minutes.

Works great with SDR software and virtual audio cables! Run up to 8 GMDSS decoders in parallel at the same time, each tuned to a different frequency.

You can change the color scheme and font type/size to your preferences.

Black Cat GMDSS is available for download and trial prior to purchase, so you can make sure it works correctly with your setup. It's available for Windows 8 and 10 (Windows 7 is not supported) as well as macOS.

Nils Schiffhauer (DK8OK) has a review with usage tips that may be helpful.

The main window displays recently received messages along with a convenient and thoughtfully arranged user interface (click on any image below for a full sized version) with decodes from each frequency both separately shown as well as combined into one view:

Messages from coastal stations are also separately broken out into their own display, with a concise and easy to read single line format"

Another window displays a table summary of all received transmissions from coastal stations, on a per frequency and total basis. This information is stored on disk and retained from run to run:

Coastal stations with messages are also displayed on a map, which can be panned and zoomed as desired, along with the total number of messages from each station:

There's also a database of all received messages, which can be searched and sorted based on all the possible parameters:

Buy Your Copy of Black Cat GMDSS Today

Start decoding GMDSS transmissions in just minutes!

$29.99 Registration code sent by email, software download

Black Cat GMDSS is only $29.99 (Introductory pricing). Purchase also entitles you to all updates and new versions released over the next full year, free of charge, which of course you can continue to use forever.

Free To Try!

Not sure you're ready to buy Black Cat GMDSS? You can download a fully featured copy to try out, before you buy it.


Beta Versions:

Preliminary beta versions. Likely to have bugs. Features/appearance/operation will evolve, perhaps substantially, over time. As updates can always break things, or change program features/operation, please be sure to keep a copy of your existing version when download a new version. I have noticed an issue with the Windows version crashing after several hours of use, I am investigating this.

Black Cat GMDSS 0.7.2b1 for Windows - Windows 8 / Windows 10 - 4 December 2021


Black Cat GMDSS 0.7.2b1 for Mac OS X - Mac OS X 10.10 to Big Sur - 4 December 2021


A virtual audio cable/driver is required for use with SDR programs. We have a list of third party programs here.

GMDSS Frequencies: 2187.5 kHz, 4207.5 kHz, 6312 kHz, 8414.5 kHz, 12577 kHz, 16804.5 kHz.

These are the transmit center frequencies, if you set the center frequency in Black Cat GMDSS to 2000 Hz, then tune 2 kHz lower.


Email your comments and questions to info@blackcatsystems.com

Last modified December 4, 2021