Category Archives: Maritime

GMDSS & Display Launcher: Monitoring seven Channels in parallel


GMDSS-Display reading decoded data streams from seven MultiPSK’s instances in parallel, presenting all information neatly in one database.

GMDSS is a system of ship-coast and coast-ship digital communications on six main HF channels. At an average location in Germany, you will receive about 5000 messages altogether during 24 hours.

In the past, I mostly used the excellent and free YaDD software to decode all channels in parallel (yes, YaDD can be opened in multi instances, each one in a separate folder).

During HFDL monitoring, I came across Mike Simpson’s free software Display Launcher which neatly collects now up to 24 different data streams, coming from up to 24 HFDL channels in a clear database format.
Mike’s software also contains a module called “GMDSS-Display” which now works similar in collecting datastream from up to seven GMDSS data streams, decoded by MultiPSK software.

Yes, also MultiPSK can be opened in many instances, each one in a sperate folder. By this way, it accepts e.g. the audio input of seven different GMDSS channels from an SDR via each different VACs, and decodes each of them.
To do so, the decoded data of each MultiSPK instance has to be backed up regularly:
Configuration -> Regular back-up -> 20 sec
Then, decoded data is automatically written into the appropriate QSO.txt file. This, in turn, is read by GMDSS-Display. Of course you first have to set the paths to guide the software to the appropriate sources.

It takes a bit time of setting it all up, but then you may run this combination until a Windows’ update forces the PC to re-boot 😉

With Mike’s development, you have a unique and mighty tool at hand for a 360° view now also in the field of GMDSS – thank you very much!

Please find below the results of a 24 hours’ session on all seven GMDSS HF channels – coast stations only, automatically drawn onto DX Atlas. All stations received in Germany with SDR FDM-S2 and MD300DX, an active vertical Megadipole of just 2 x 2.5 m of stunning performance.


Received coastal stations on all GMDSS channel/HF during 24 hours in Germany world-wide and …


… those with a focus onto Europe.

Utility DX: Some (actually: 1.000+) Logs, June, 2016

Part of the EXCEL list

Part of the EXCEL list

“HF for the pros is stone-dead, isn’t it?” This rather verdict than question is often heard even by hams. If you are telling them how busy the bands really are (as they cannot read about that in their magazines), they are doubting: “But you need professional equipment plus decoding software, worth my Mercedes Benz?”, they are upset by the answer: “Absolutely bullshit. A software-defined radio at 500 US-$ plus some free software will produce thousands of logs!”

Still don’t believe that? Well, here is the first thousand, caught just in the first half of June, 2016. Received with an FDM-S2 receiver at a quadloop of 20 m of circumference. I mostly concentrated on fixed (rather than: mobile) stations and of modes which can be decoded with free software – if they are not even outright SSB or CW.

You can download this log: Logs_EXCEL from where it may easily be opened not only by EXCEL, but also e.g. free LibreOffice.
If I find time, even more logs from the same HF recordings will be added.

I am greatly indebted to the busy and resourceful friends of UDXF for their work, thanks.

20 MHz HF: “HackRF One” on Shortwave

world Kopie

The world is full of software-defined radio (SDR), but HackRF One has a rather unique position – thanks to its vast maximum bandwidth of 20 MHz. With an up-converter, this combination covers more than 70 percent of the whole HF range from 3 to 30 MHz. Even better: with proper software you can record and play this enormous band!

However, this stunning bandwidth is achieved by a moderate resolution of 8 bit, resulting in a dynamic range of just nearly 50 dB. Or the half of SDRs like Elad’s FDM-S2.

Anyway. I wanted to know in practice what you can actually do with such a set at a budget price plus mostly free software. The results surprised even me: Properly used, this combination convinced as a quite decent performer on HF! The world map above shows some of the stations received with the set (see insert bottom left) to test its performance.

I laid down my experiences and recommendations for best reception in a paper of 17 multi-media pages full of examples – including 55 screenshots, 21 audio clips and one video. The PDF shows how to optimize reception of broadcast, utility and amateur radio stations. It covers many examples on how to analyze recordings, to decode data transmission with free software plus live decoding of 14 channels in parallel. It also gives some examples of combining HF reception with the internet, e.g. regarding the reception of signals from airplanes (ARINC, HFDL) and vessels (GMDSS).

My experiences really left me enthusiastic about this set.

You may share this enthusiasm and download the PDF of 43 MB here. Save it on your hard disk or USB stick, and open it with a most recent Adobe Reader. Otherwise, the multimedia content will not work.
[Einen deutschsprachigen Test  habe ich jeweils als Titelgeschichte in der April- Ausgabe 2017 der Fachzeitschrift  Radio-Kurier – weltweit hören und in der Mai-Ausgabe der Fachzeitschrift Funktelegramm veröffentlicht.]