Tag Archives: Software

GMDSS & Display Launcher: Monitoring seven Channels in parallel

DiplayLauncher_4

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.

DXAtlas_5

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

DXAtlas_6

… those with a focus onto Europe.

TDoA Direction Finding: First Experiences on the KiwiSDR Net

6465_5

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.

SDR Console V3: New and indispensable Software

V3_Dimtsi

“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).

All

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
6pane

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

 

1520

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!

4800

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.

 

7435kHz

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.

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.

Offset/SNR: Some Ideas for Medium Wave DXing

Offset_5

Offset-DXing “on the fly” shows four different stations (spectrogram) on one nominal channel, namely 801 kHz. The window is baout 30 Hz wide and shows the carrier on HF level.

Although I use Simon Brown’s excellent software SDR Console V3 for years, I only now discovered a feature, being most valuable for medium wave DX.

Nearly each medium wave channel is populated by a couple of stations which mostly have a slight difference from each other, called offset. This often is specific to specific stations. It even reveals stations too weak to be heard. Software V3 will show these carriers of HF level during normal listening, being live or from an HF recording.

Read MW-Notes, to get some information on “how-to” on 6 pages, with 12 screenshots. There you will find also a hint for a method with even much more resolution (but: not “on the fly”) plus some information on how to measure signal strength and estimate/calculate the SNR of speech/music, rather than that of just the carrier.

You have to distinguish between absolute and relative frequency accuracy; the first is best achieved with a GPS-disciplined oscillator, the letter the normal case.

P.S. I started with these things back in 1997 with an evaluation board from Motorola, followed by sound card & software on audio level (“Soundtechnology zeigt Signale: Sieh’, wie es klingt!”, funk magazine 6/1998), to be continued on HF level from 2006, first with RFSpace’s groundbreaking SDR-14. Three years later, I published a survey of each and every 9- and 10-kHz-channel on medium wave by this method. After Apple closed their web service, these pages had gone astray, and the information is now not up-to-date anymore. State-of-the-Art now is the method described in the paper.

GRAVES: Reflections out of the blue

A GRAVES reflection from a meteor trail, August 21st, 2017 at 10:51 UTC. Received with FDM-S2 from Elad, a discone antenna and software V3 from Simon Brown

Undoubtly, a Graves is a fine French wine from the Bordeaux region in western France. So it is so surprise that also GRAVES is an extraordinary Radar station. It was built to detect and follow satellites and their debris. They sequentially cover from 90° to 270° azimut in five big sectors A to D, and change from sector to sector each 19,2 seconds. Each of this sector is further divided into 6 segments of 7,5° width, covered for 3,2 seconds each.

They are transmitting on 143,050 MHz. If you are in Europe and tune into 143.049,0 kHz USB, you probably will hear/see some reflections of meteors, airplanes and even spacecraft. The distance between the transmitter and my location is about 630 km, and for their southly directed transmissions, there most of the time is no direct reception.

So, if you tune into 143.049,0 kHz, you will see just a blue spectrogram: noise. If you wait for a while, some signals will appear out of this blue; see screenshot on the top. With Simon Brown’s free software Version 3 you may also take a level diagram in smallest time steps of just 50 milliseconds:

A level diagram of the meteor trail reflection from the spectrogram at the top, visualized qith QtiPlot.

This level diagram shows the big advantage of SDRs, working on the signals on HF level, rather than of audio level as with legacy radios. The latter additionally introduce e.g. noise and phase errors. Of course, you may also listen to this signal:

From this audio, in turn, you may do an audio spectrogram, possibly revealing further details of e.g. of the trilling sound like that from a ricocheting bullet: The Searchers (the 1956’er Western film by John Ford, not the British boy group from 1960 …) on VHF.

Audio spectrogram of the sound, revealing “packets” of sound which result in the trilling audio. At start, these packet show a width of about 42 milliseconds to be reduced to 37 milliseconds.

P.S. If you want to donate: my favourite Graves is from Domaine de Chevalier, blanc …

SDR Console V3: Signal History and six RX Panes!

KPL

NEW: The Receivers’ Pane on top covers spectrum and spectrogram of up to six demodulators – look at different modes and bandwidths. Also new: “Signal History” at the bottom.

Simon Brown, G4ELI, has further developed his software SDR Console which has become THE platform for a real bunch of very different SDRs. The new public preview has two more exciting features:

  • “Signal History” takes the signal strength of the given bandwidth each 50 milliseconds, which can be saved in a CSV file. It is also shown in three different speeds on a display.
  • “Receivers’ Pane” shows up to six combos of spectrum/spectrogram of the complete up to 24 parallel demodulators (they additionally can be shown in the Matrix, as in former versions).

See screenshot on at the top.

“Signal History” offers many applications, to name just three:

  • analyze fading and its structure with an unsurpassed time resolution of 50 ms
  • document fade-in and fade out
  • measure signal-to-noise ratio of signals

As an First Aid, I have written a PDF of 19 pages with 36 instructive Figures. There you find a step-by-step introduction plus numerous example on how to use this valuable tool in practice. Please download it here. (Another tab opens, where you have to double-click “SDR_COM_Marker” to start download.)

Surely, I will come back to these most welcomed features in more detail. For now only some screenshot examples regarding “Signal History”, which have been realized by analyzing the CSV files with QtiPlot:

With some statistics applied on the CSV file of Signal History, you’ll get a deep inisght into fading structures. Top: original data (black), averaged (yellow), median (read line). Bottom: box diagram, histogram, 3D-band. See following screenshots for some examples.

 

… and this is just the beginning! [Receiver: Elad FDM-S2 & AirSpy with SpyVerter]

AirSpy: How to listen to DAB+ Broadcast

It’s pure fun to listen to N-Joy, a North-German broadcaster, in DAB+. This digital mode should replace all classical FM broadcast, and has already done this in some countries where others offer both – like Germany.

DAB+ takes place in former TV bands. Several stations are bundled in a bouqet. In Germany, one usually is in comfortable reach of at least one of these bunches, see footprint on a map, with stations around my location:

map

Footprint of DAB+ broadcasts in Germany. Pin = my location. In the list you see the stations plus the channel (“bouquet”), here 5C omnidirectional from Hannover with 10 kW and 6C, also from Hannover, but pointed to the east, with 8 kW.

As AirSpy is covering also these frequencies with high sensitivity and a decent dynamic range, I gave it a try.

First software used is called Welle (English: wave) by a team around Albrecht Lohofener. I use it on a PC/W10. It’s easy to install, and then start it by the usual double-click. An MS-DOS windows opens, starting a routine for searching and opening the AirsSpy connected to your PC. This window informs you on all steps the software is doing.

Then the graphical user interface starts. First you have to scan the bands: click “Sendersuchlauf -> Start” (the software detects on what country code your OS is running and switches automatically to e.g. English), see screenshot:

Welle

The scan is running, 13 stations have been found so far. With expert mode (“Expertenmodus”) activated, you see the spectrum of the frequncy set being scanned.

From the spectrum (right), you might see if HF gain ius ok, or that you should go from automatic (“Auto HF-Verstärkung”) to manual gain control (“Manuelle Versätrkung”) to either imporve sensitivity or to avoid distortion due to strong transmitters nearby. With me, “Auto” drives fine.

After finishing the scan, “Welle”  comes down with the bouquets in reach:

Sputnik

Just click your station from the list on the left, and the station will be heard. Many of them provice additonal information, as here MDR Sputnik with weather. On the right you again see the spectrum of the whole bouquet (6B, 183,648 MHz) plus additional information an the quality.

Secondly, a more technical approach is offered by Jan van Katwijk with also free Qt-DAB. I also use it on my PC/W10. After downloading the suite, containing also other intersting software, just start “qt-dab-0.999”. An MS-DOS windows opens, followed after some seconds by the GUI. Here you have to define the receiver from a drop-down list, choose the boquet (5C, in this case), and scanning serves you the stations’ list. You may have up to five different windows open – from the MS-DOS window to more detailed technical data, including a QPSK phase window, right from the spectrum.

QT_2

Qt-DAB presents you with up to five windows: MS-DOS on top; gain control main window and technical data below, and spectrum plus QPSK phase constellation at the bottom. “Klassik Radio” on 173,352 MHz playing Bach: “What God does that is done well”. Not to talk of what the authors of the DAB software had done …

Thanks to both, Albrecht and Jan, to have developed this fine piece to software, free of charge!

iZotope RX6 – A Miracle in restoring Audio

If you still desparately looking for a software to restore your recorded DX audio clips, iZotope’s RX6 offers an alomost perfect solution. While the de-crackling tool automatically removes all of these annoying statics, the near-unbelievable tool “Spectral de-noise” is doing wonders in extracting e.g. formants of speech out of noise, thus greatly enhancing intelligibility.

I did a convincing test with a clip of CKZN, New Foundland’s shortwave station still transmitting on 6.170 kHz with 1 kW; received June 1st, 2017 at around 02:00 UTC. The original recording is heard like this:

It looks like this, when opened in RX6, with spectrogram in the background:

CKZN_1

First step was to automatically get rid of most of the static by “de-crackling”. RX6 offers you the chance to see also the garbage, e.g. what has been subtracted from the signal, see screenshot below with a focus on the identified crackles:

CKZN_6_2

After this first step, the audio sounds like this:

Second step is the tool “Spectral D-noise”. Most comfortable is the “adpative mode”, where you see the audio much more clearly than in the original recording:

CKZN_6_denoise

And that’s the way, it sounds, with 12 dB attenuation of noise (default):

Another mode is the “learning mode”, where you teach the software what it has to consider as noise in the recording, and then clean it up. First, I did it with the strongest value of 40 dB reduction:

Sounds quite artifical – but drop your ear onto the last part, how clean the jingle sounds!

With some right, default is 12 dB, listen here:

This may be reduced to even 6 dB – you have to find the right balance by yourself:

To restore audio of DX MP3 clips, is not where this software is really adressed to. But even for this purpose, it’s strong algorithms perform better than any other device/software, I’ve seen in the last 50 years. And there are a lot more functions to tweak a signal further. Not really cheap, but unique. There’s simply nothing better!

 

PC-HFDL Display: Receive, decode and analyze the biggest net on HF!

HFDL is a net for data communications between airplanes and ground. The results can be shown on Google Earth . This screenshot shows a part of 29.000+ entries, received and processed on August 15th, 2016.

HFDL is a net for data communications between airplanes and ground. The results can be shown on Google Earth. This screenshot shows a part of 29.000+ entries, received and processed on August 15th, 2016.

 

Communications between air and ground is mostly done on VHF, UHF and SHF. But if an aircraft is out of reach of a ground station station due to the limited “radio horizon” of these bands, it has to maintain communications by either satellite or HF. This HFDL net is in fact the most massive professional user of HF right now. Within 24 hours, I get more than 40.000 live messages with a modest equipment.

With his software Display Launcher, Mike Simpson from Australia provides a most valuable tool to analyze up to nine channels in parallel. His software also draws positions and routes onto Google Earth. Mike has spent much energy on coping with many inconsistencies of transmitted data before it all really goes smoothly.

This free software is the vital part of a monitoring project to receive, demodulate and analyze live up to nine HFDL channels in parallel. Other ingredients you need is a software-defined radio (SDR), nine virtual audio cables (in fact, a piece of software) and a decoder software. Don’t forget an antenna and a PC …

This setup comprises a semi-professional monitoring station which will allow you to receive and track many of the nearly 3.000 airplanes using HFDL. This also covers the military, business jets, helicopters and some other delicate users. It maybe used as an important complement to Flightradar24’s web service, whenever their VHF/UHF/SHF-based net is out of range of the aircraft. This is particularly true over vast water masses like oceans and sparsely populated land masses. Furthermore, Flightradar24 erases some sensible flights from the raw material before publication on their website. This is clearly no “censorship”, but some thoughtfulness in regard to those countries where reception and publication of HFDL data is more tolerated than explicitly encouraged by the government.

In a 9-page PDF, I published a step-by-step recipe on how to set up such an HF monitoring station for up to nine parallel HFDL channel. You can download it here.

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