Author Archives: DK8OK

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.

TDoA Direction Finding: First Experiences on the KiwiSDR Net


With some iteration, as described in the PDF, the former unknown site of a CIS-12 transmission on 6.465 kHz has been disclosed as the Russian Navy from Baltysk, Kaliningrad.

The stunning direction finding tool on the KiwiSDR net has hit the community. Most people are enthusiastic about the new horizons, some some smart people had opened for free.

A few people, however, reported some disappointment as they couldn’t pinpoint each and every transmitter with expected high precision.

To avoid this disappointment, you have to know what you are doing. The TDoA tool for direction finding indeed delivers automatically stunning results. But you have to think a bit about the setup, and also do some iteration.

I wrapped up my first experiences with TDoA in this PDF. You may simply download it by double-clicking the link, and open it in a PDF reader. It consists of 22 pages and 37 instructive figures. I greatly stressed the practical part of direction finding with this tool – with 13 explicit case studies from 2,6 MHz to 15,6 MHz.

The idea is to have more fun by getting the most reliable results.

TDoA on KiwSDR Net: Direction Finding for All!


Four receivers are nailing Saissac as transmitter site of STANAG 4285 transmission on 12.666,5 kHz on July 16th, 2018, 15:45 UTC.

A dream has become true: direction finding (DF) in the range of 0 to 30 MHz for all! The method is “time difference of arrival”. This is a speaking term, and it works exactly like it says: measuring the different times of arrival of a signal at at least three different receivers and calculating the position of the transmitter.

Base is the net of KiwiSDRs. If connected to GPS, each of this SDRs is able to deliver an I/Q stream with time stamps of a very high resolution. If you compare the recordings of different receivers tuned to the same station at the same time, you will find as slight time difference from receiver to receiver. This is due to the “time of flight” from transmitter to receiver. HF is traveling 300 km per 1 millisecond – so time is distance.

However, you don’t know the absolute transmitting time on transmitters other than time signal stations. So “Time Difference on Arrival”, or TDoA, measures the time differences of arrival. The first step is to compare the I/Q streams to find at which time difference their content does correlate. From these time differences, there are calculated curves onto a map. They cross in that region, where most likely the transmitter is located – see the screenshot at the top which I did to locate the STANAG 4285 transmitter on 12.666,5 kHz.

Due to concept, most reliable results (and, hence: sharp regions where the curves meet) are achieved only with the same propagation mode prevailing at all receiving stations. This is most strictly the case on VLF and long wave, where we mostly have one and stable waveguide-like propagation. But you can achieve also stunning results on HF if you carefully choose the SDRs – see next picture.


Here the broadcast station at Issoudun on 15.320 kHz has been pinpointed by G0EVX, OE5EAN and OZ1BFM receivers at 08:35 UTC. The tip of the arrow points to the actual location, just one kilometer south of the RDoA result [see scale!].

As soon as we approach skywave propagation, you must care for more or less the same propagation mode, of which a one-hop propagation (e.g. 1 x F2) should be preferred. Often even a bit bigger heat map of correlation gives a significant clue from where the transmitter is operating  see next picture.


An even weak and fading CIS12 signal 11.836 kHz (spectrogram at the bottom) has been reliably located on Crimea, Sevastopol area. Hence, it is most likely associated with the Russian Navy there.

The software has been developed by some smart people around Christoph Mayer who also provides detailed information on the concept of this approach on his website. It quickly has become an extension of the KiwiSDR net. This makes it very comfortable to use – if you take care of what is said above.


SDR Console V3: New and indispensable Software


“Living Sonagram”: On the right window, you see a part of a 24 h recording at 6,1 MHz bandwidth (ca. 2 TB) with 1 line/second. Tagged is the sign on of Dimtsi Hafash which is received by the undocked “Receive” panel of V3’s GUI. At the bottom: signal strength on 7180 kHz over 24 hours reveals e.g. s/on, s/off and fade in.

Just a small note on a real real big event: Simon Brown, G4ELI, has published V3 of his indispensable SDR Console software on June 18th, 2018 – after three and a half years of heavy coding. Download it here and donate. Or vice versa.

V3 is a quite universal software for most SDRs on the market. For all, it provides the same graphical user interface (GUI) and the same functions (plus those specific to some devices).


DXer’s delight: On top the sonagram to visually catch signals (here: JDG from Diego Garcia; tagged). Bottom, from left to right: receive GUI for fine tuning, decoder W-Code showing “JDG”, below this “Playback” panel for controlling the recording (back/forward, e.g.), and on the right a database.

There are many unique functions and modules which will take DXing with SDRs to the next step. For now, let me mention just two of them:

  • 24 parallel demodulators within the SDR’s bandwidth – fully independent in e.g. mode, bandwidth and AGC to receive, record and decode 24 signals/channels in parallel.
  • a sophisticated File Analyser  which presents a recorded band as “living sonagram” – whre you see and click to a signal which then is played via the basic GUI

Up to six parallel demodulators can be seen on the main screen (from up to 24 possible).



1520 kHz from 18:00 to 05:00 UTC (local SR/SS: 19:43/02:58 UTC) with 100 Hz bandwidth and 0,0031 Hz resolution (= +65 dB over 10 kHz!) reveals at least 27 stations and their offsets.

Each of these just two features mentioned will open new worlds for DXing and even serious professional monitoring. I will be happy to come back to some applications of V3 in more detail.

Thank you very much, Simon, for providing this excellent tool for free!


4’800 kHz: First CNR1 with sign on at 20:15 UTC and fade out, then AIR Hyderabad with the same, but s/on around 00:06 UTC.



You may export levels over time on one frequency or level over frequencies at a given time. This graph visualizes the activity on 7435 kHz with 86’400 levels (on per second over 24 h). The data had been exported to QtiPlot for further investigation.

DARC: 25 Jahre “vereinsschädigendes Verhalten”

Innerhalb von nur 25 Jahren hat sich die Mitgliederschaft des DARC beinahe halbiert, seine technische Kompetenz – siehe SDR-Transceivernetz – ist allenfalls  diskutabel, sein Verhältnis zu Behörden erodiert, und statt klassischem Ham Spirit finden sich Denunziation sowie Diskriminierung. Was ist da passiert?

Bis in die 1990er-Jahre hinein hatte sich die Mitgliederzahl des DARC e.V. positiv entwickelt. Dann jedoch schlugen seine Funktionäre sehenden Auges eine Politik ein, mit der sie  den “Bundesverband” auf praktisch allen Ebenen massiv schädigten.

Den Wendepunkt markiert das Jahr 1993. Es ging damals u.a. um die Frage, ob Funkamateuren der Kurzwellenbetrieb ohne den Nachweis von Morsekenntnissen (CW) erlaubt werden sollte. Interessanterweise kam dieser Vorstoß aus dem damals hierzu zuständigen Ministerium. Also nicht etwa vom “Bundesverband für den Amateurfunk”, wie der DARC e.V. sich gerne nennt.
Der DARC lehnte den Verzicht auf die Morseprüfung jedoch nicht nur ab, sondern ließ mit seinem “CW-Statement” jene Funkamateure, die sich der CW-Prüfung nicht unterziehen mochten, wie lernfaule Charakterschweine aussehen.

Angst vor innovativer Technik

Ich allerdings hatte im Gegenteil den Verzicht auf die CW-Prüfung und zur Förderung des Amateurfunks schon lange vordem vertreten: der Abschaffung der CW-Pflicht sollte man eine ideelle Unterstützung zum Erhalt der liebenswerten Betriebsart zur Seite stellen – was ich u.a. durch die Vorstellung vieler Morsetasten und ihrer Eigenheiten in der Fachzeitschrift “funk” tatkräftig, öffentlichkeitswirksam und weithin einzigartig unternahm.
Im Gegenzug zum Verzicht auf die CW-Prüfung wäre der Amateurfunk attraktiv für die sich damals bereits abzeichnenden Digimodes geworden, deren Entwicklung und Betrieb ganz andere Fähigkeit als die Beherrschung der Tastkunst erfordert – und ohne, dass man deren Freunde verliert.

Funktionäre können nun kräftig feiern!

Der DARC-Vorstand jedoch setzte sich in der darauf folgenden Auseinandersetzung in objektiv vereinsschädigender Weise durch: die jeweiligen Vorstände schickten mit ihrer Politik die Zahl der Mitglieder des DARC in einen nachhaltigen Sinkflug: von 60.000 im Jahre 1993 auf rund 34.000 im Jahre 2018. Die aktuelle Zahl ist geschätzt, der DARC gibt [auch?] Außenstehenden zu diesem Niedergang offenbar keine Auskünfte.

2018 also können so manche Vorstände des DARC und so manches Ehrenmitglied miteinander “25 Jahre objektiv vereinsschädigendes Verhalten” feiern. Zum Verlust fast der Hälfte der Mitglieder schädigten sie den Verein überdies um weitere, oft sechsstellige Summen. Etwa durch ihre laienhafte Personalpolitik. Aber wenigstens eines ist kräftig gewachsen: ihr Spesenbudget.

Das falsche Schwein geschlachtet

25 Jahre auch ist es her, dass der DARC ausgerechnet mich wegen “vereinsschädigenden Verhaltens” ausschloss. Darauf ist er bis heute so stolz, dass selbst aktuelle Vorstände gerne bei jeder sich bietenden Gelegenheit darauf erneut aufmerksam machen.

Neben dem “Silberjubiläum” ein Grund mehr darauf hinzuweisen, dass sich mein angeblich “vereinsschädigendes Verhalten” ausschließlich in der Phantasie der Funktionäre abspielte – im Gegensatz zu deren Verhalten, das den Verein bis heute ganz konkret und Monat um Monat, Jahr um Jahr schädigt.

Ich hingegen bin – auch und gerade öffentlich – immer für einen starken DARC und dessen kräftiges Wachstum eingetreten. Das ist in unzähligen Zeitschriften- und Zeitungsartikeln dokumentiert.

Bis heute nix gelernt

Die für den DARC offenbar auch nach 25 Jahren weiterhin hochaktuellen Ereignisse (meine vielfältigen Versuche, auch mit Rückenwind von Distriktsvorständen, dem Verein wieder beizutreten, scheiterten bis heute am Bundesvorstand – sie haben offenbar nix gelernt) hatte ich zum Anlass genommen, der Fachzeitschrift “Funktelegramm” ein Interview zu diesem Thema zu geben. Ihr könnt es hier nachlesen. Zugleich stelle ich hier meine Rede zur Verfügung, die ich 1994 auf der Hauptversammlung in Cottbus gehalten hatte.

Dr. Ellgerings Weitsicht: “Fernere Zukunft”

Der damalige DARC-Vorsitzende Dr. Horst Ellgering, der den Verein, aber auch den Amateurfunk insgesamt mit knatternden Fahnen in diesen Schlamassel führte, erklärte am 7. November 1993 in einem seiner diffamierenden “Offenen Briefe” ausgerechnet mir gegenüber:
“Was Deine Aktivitaeten fuer den Amateurfunk bedeuten, mag jeder fuer sich beurteilen. Endgueltigen Aufschluss bringt hierueber erst eine fernere Zukunft.
Nun ist ein Vierteljahrhundert rum. Was seine Aktivitäten und die seiner Nachfolger brachten, wissen wir langsam. Und natürlich kam das heutige “Ehrenmitglied” des DARC niemals auf seine Bemerkung zurück.

Einführung SDR: Kompakt, praxisnah, verständlich

Wer eine konzentrierte, praxisnahe und verständliche Einführung in die Technik Software-definierter Empfänger (SDR) sucht, der findet alles dazu in einem 28-seitigen und deutschsprachigen PDF von Hayati Ayguen.

Nach der spannenden Lektüre kennt man die Chancen ebenso wie die Grenzen von SDRs, kann die Prospektdaten und vollmundigen Werbeversprechen vor allem der großen Hersteller von Amateurfunkgeräten besser einordnen und lernt somit auch die Leistung sowie den Funktionsumfang der Produkte kleinerer Hersteller noch stärker schätzen.

Einen ersten Überblick bietet Hayati auch auf Folien.

INMARSAT: Decoding 12 Aero-channels in parallel


Action: Free software allows for decoding twelve INMARSAT in parallel

A recent post in Carl’s rtl-sdr-blog informed about the ebay-lability of some surplus Outernet patch antennas for just – see here. For just 29 US-$, I got this small antenna with integrated SAW filter (1525 – 1559 MHz) plus LNA. A real bait for me to jump over the limit of 30 MHz reception! Soon I fired up my AirSpy R2 receiver, providing the LNA with power supply (Bias-Tee). It worked fine, and I received a whole bunch of excellent signals by this setup.

As I wanted to receive some aircraft information, so I downloaded free JAERO decoder of Jonathan “Jonti” Olds, also from New Zealand. This fine software can be opened in many instances. In combination with the up to 24 decoders of SDR-Console V3 of Simon Brown, this modest setup turned into a multi-channel satellite reception post.


Here 12 decoders had been assigned – one on each INMARSAT channel. You see also quite good SNRs from the Outernet patch antenna.

Next steps worked as usual with the mutli-channel approach:

  • make up 12 channels in SDR-Console and tune each channel to a different signal. Mode must be USB, and as bandwidth I choose 1200 Hz for 600 bps and 2400 Hz for 1200 bps channels. That’s a bit wider than necessary, but doing so there is some room for the AFC in JAERO decoder always to stick to the signal even if the SDR should drift a bit over 24 h or so
  • The output of each channel is then routed to a different Virtual Audio Cable, or VAC 1-12.
  • Then you have to install twelve instances of JAERO software in different folders, e.g. JAERO 1-12. You should name each JAERO.exe file accordingly, e.g. JAERO_1.exe to JAERO12.exe.
  • Open JAERO_1.exe, assign its input to VAC 1, and set the matching speed of the signal. If all is ok, you will be rewarded by a sharp phase constellation, and soon decoding will start.
  • Repeat the above steps until you have reached JAERO_12.exe, connected to VAC 12.

The “Matrix” of SDR-Console V3 shows the twelve channels with different signal strengths and width, depending on the data rate (600bps/narrow, 1200bps/wide).

The result can bee seen from the screenshot at the top of this page. The whole setup ran stable and unattended for hours.

Thanks for all smart people having developed the smart software and hardware!

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