Monitoring: Visualizing with free Tableau Public Software

Part of a multi-channel monitoring of the HFGCS net in ALE on July 14, 2019: the vertikal axis shows the channel, the horizontal axis the time of monitoring.

2019 is the year of groundbreaking Software-defined radios, covering the whole HF range of 30 MHz width and recording it for many hours, e.g. from midnight to midnight. In combination with proper software, this allows for a fresh view onto monitoring.

For the screenshot on the top, I had monitored nine HFGCS channels from 3137 kHz to 23327 kHz in parallel (the 18003 kHz didn’t work, sorry) with Winradio’s SIGMA SDR, running with Simon Brown’s free software SDRC V3 and nine instances of MultiPSK decoder.

After automatic monitoring, I harvested all time-stamped logs stripped them from information not needed, and imported them to free Tableau Public software to visualize activity according to station, time and channel. This gives an overview on the monitoring session, propagation, time sequences of hopping from channel to channel etc. – you might zoom into the screenshot for a clearer look.

Thanks to Tableaus also stunning geospatial features, completely other views of the same log are available. The screenshot below shows the number of logs on all channels of a monitoring session of 12 hours.

Geospatial information of the stations, combined with the number of log entries on all channels.

You may zoom into this OSM[ap], and you may also have a zoomed satellite view (or this or that) which directly hits the feeder point of your antenna … if you know the exact location and this is a part of your log entry – see screenshot below.

Zooming the map above onto JDG at satellite view, directly leads you to the location of the station – here Diega Garcia US Military base.

The most versatile Tableau software also allows to relaize many other ideas to visualize monitoring; some of them already above horizon, others still below. To conclude this entry, I did a visualization of all HF stations/channels of AFAD, the Turkish Disaster and Emergency Management Authority, heard by me over the last 18 months. Each (?) of the 81 Turkish provinces maintains an AFAD base, and all (most?) of them are communicating on HF. As Tableau has many detailed geographical already aboard, a visualization of channels/province being heard is easy.

Analyzing part of a logbook: All Turkish provinces heard with ALE signals of AFAD are colored – the deeper the color, the more channels were received in the last 18 months.

Dream Team: Winradio’s SIGMA and Simon’s Software (1)

All main six GMDSS channels on HF at once: Winradio’s SIGMA with Simon Brown’s software SDRC V3

Some days ago, I wrote about my very first experiences with Winradio’s groundbreaking SIGMA SDR receiver, covering e.g. the whole HF band with 32 MHz width and 16 bit resolution – plus much, much more. SIGMA comes with a fine software, and provides an API.dll for connection to 3rd-party software. Thankfully, Simon Brown, G4ELI, adapted his unique SDRC V3 software to this (and other) Winradio in nearly no time.

This combination has become a real dream team: the best hardware and the best software avalaible. The screenshot at the top shows just one example of others which will follow: I made a 24 hour recording of 0 to 25 MHz (7.85TB) and placed six demodulators on the main GMDSS channels on HF between 2 and 16 MHz. You see each channel in a separate window at the top of the screenshot, showing spectrum and spectrogram with time stamps of the recording. Below those six channels you see spectrum and spectrogram of the whole recorded bandwidth, namely 25 MHz. Eventually, below this spectrogram you see 60 x 24 boxes, one for every minute of the 24 hours recording. Just click into the time you want, and the recording instantaneoulsy to it.

Demodulated audio is guided via VAC1 … VAC6 to six different instances of the free YAND GMDSS decoder – see screenshot at the bottom.

There are great many other applications of this revolutionary combination to which I will come back later.

Parallel reception & decoding of six GMDSS channels at once.

16 bit, SDR: The new Redpitaya!

At last: It works!

The new Redpitaya (RP-16) has arrived here, see photo gallery at the bottom. With now 16 bit and a largely improved input section, it promises to match amateur’s and SWL’s needs for an able SDR transceiver or receiver even better than its predecessors with 12 and 14 bit.

My initial idea was to get a nice, fool-proof, competetive SDR with up to 30 MHz bandwidth for just around 450$. However, from start, the RP-16 seems to test more me than vice versa. First, me and a most capable friend didn’t get it going at all. Here, secondly, Joerg, DD8JM, stepped in and did wonders with the Micro card from which the RP-16 has to read its software after sniffing power. It turned out that the card had two partitions and three software versions on the card – which you cannot see with Windows od Mac OS, but with Linux only. And RP didn’t liked that. Thankfully, Jörg tided up the card, and it worked – at least over a router.

The only SDR software available at early July 2019 seems to be openHPSDR. So, over a modem it all worked in general, see screenshot at top. But there were annoying audio drops and occasional overdrive from strong signals – despite an extra 30 MHz low-pass filter from Heros and bright daytime.

Despite having worked on this for many hours, I am still not quite sure who is testing whom. At least so far, my test of the new Redpitaya was disappointing. Maybe it will live up to my expectations under another software, namely Simon Brown’s (G4ELI) SDRC. I will see, because with 69g only, it doesn’t make an ideal paperweight …

If you made different experiences, tell me!
I would be more than pleased to jump in and spread such welcomed news.

Winradio’s SIGMA: “… the Killer speaking!”

Winradio’s Sigma is here covering the whole HF range from 0 to 32 MHz (top left, spectrogram), with brodcaster CRI on 15’410 kHz demodulated (top right, spectrum) and the complete range of 0 to 88 MHz (bottom, spectrum).

When I saw the late Chuck Berry in concert with Jerry Lee Lewis, the latter was announced as: “… the killer speaking!” Having switched on Winradio’s WR-G65DDCe, or ‘Excalibur Sigma’, the also breathtaking show of this receiver reminds me to that concert: The Sigma is also kind of a killer to all other software-defined radio (SDRs) for which it now defines the benchmark in nearly all aspects.

It comes as the top model of a highly respected line of SDRs from Winradio in Australia, which pioneered the market of high performance receivers defining the state of the art. For hobbyists, the Winradios often define the utmost price tag they want to pay. Whereas professionals, in opposite, are happy to get an excellent peformance at modest costs. Yes, buying the Sigma will set you back nearly 7’000 Euros, but: “Madame, there is no second.”

What makes the Sigma unique? First, it is its covering up to 64 MHz with 16 bit resolution flawlessly over an USB3.0 connection, resulting in a spurious-free dynamic range of 111 dB (2 dB lighter with pre-amplifier). You may record this full range even onto external hard disk without loosing a bit. Then you may play back and tune it as live from the hard disk, offline and flawlessly. The whole HF range from 0 to 32 MHz needs about 155 MB/s with even some headroom when doubling the range to even 64 MHz. Winradio says, the Sigma will run from a quad core, and they are right: I have it running from a laptop Dell Inspiro 5770 with i7 8550U @1.8 GH, 4 cores, 16 GB RAM, 2TB hard disk. CPU usage during recording a 32 MHz wide range was never over around 12%.

From start, Winradio has built up a solid reputation to combine professional hardware delivering top performance with intuitive software, resulting in a nearly unsurpassed user experience. As you can rely on the published data, I want to concentrate on Sigma’s practice. This will be a work in progress as it should include some time-consuming recordings and comparisons.

P.S. UK’s „Radiouser“ and Germany‘s „Funkamateur“ will publish an in-depth article on the Sigma in their September issues. Stay tuned.

ALE [MIL-STD-188-141A]: Which one is the best Decoder?

This is an update from my post two days ago. I have expanded the number of test signals and added some hints.

Does your decoder read this track? Buried in noise and plagued by multipath fading, the recordings below will separate the wheat from the whaff.

Often I am asked – and sometimes even asking myself! – “Which one is the best decoder for ALE?” This means: Which one delivers the best decoding under demanding conditions?

To test this, I made a recording of twelve stations “on the air” plus one weak signal, buried in Additive White Gaussian Noise, AWGN. All signals are correctly tuned, no one invers. All were read by at leastby one of my decoders “in a row”.

To test your decoders, you should download this WAV file of 131 seconds length and play it. It can be either directly opened by some decoder, or feed it via virtual audio cable (VAC) into a decoder. I used Audacity for this.

I am as interested in the results as you are – so please drop me a line to dk8ok [at] gmx.net. I like to encourage you to try all ALE decoders you have at hand – the more, the better.

Already the first results were surprising. This concerned both, the decoding ability of the decoders and the repeatability of the test. So far, the following decoders had participated: go2monitor, Krypto500, MARS-ALE, MultiPSK, Sorcerer, and W-Code. Steve, N2CKH, had written some valuable hints to optimize his MARS-ALE software for SIGINT purposes – please see his comment.


This WAV file contains the calls of thirteen ALE stations. Download and save this file (point to the icon, press right mouse button …). Then feed it to your decoders. Copy the results and send them to me. Have fun!

Ghosts in the Air Glow: HAARP on March 26th, 2019

Just after the spring equinox, interdisciplinary artist Amanda Dawn Christie did another performance of her ionospheric transmission art project “Ghosts in the Air Glow” via the High Frequency Active Auroral Project HAARP near Gakona/Alaska. I took an HF recording of a range, covering all frequencies and times scheduled – see here. At my location, on March 26th, 2019, reception was possible only on 5.100 kHz (best), 6.900 kHz, 7.900 kHz and 8.000 kHz. Signal strength was too low to hear any modulation, but the characteristics of the signals did exactly match the schedule – see screenshots and captions below.

Receiver: Elad’s FDM-S2, Antenna: Active Dipole MD-300DX (2 x 2.5 m), Software: V3 from Simon Brown


5.100 kHz, 01:16 to 01:26 UTC, West beam, gave the best signal.
The signal on 6.900 kHz on the East beam from 01:16 to 01:26 UTC was considerably lower.
On 7.900 kHz, the signal was transmitted by an electronically rotated beam, one rotation per minute, from 01:03 to 01:09 UTC on the West beam. This is clearly seen on the the Signal window below the spectrogram.
On 7.900 kHz, the signal was transmitted by an electronically rotated beam, two rotations per minute, from 01:09:30 to 01:15:30 UTC on the West beam. This is clearly seen on the the Signal window below the spectrogram.
On 8.000 kHz, the signal was transmitted by an electronically rotated beam, one rotation per minute, from 01:03 to 01:09 UTC on the East beam. This is clearly seen on the the Signal window below the spectrogram.
On 8.000 kHz, the signal was transmitted by an electronically rotated beam, two rotations per minute, from 01:09:30 to 01:15:30 UTC on the East beam. This is clearly seen on the the Signal window below the spectrogram.

Visualizing HF Networks

G-VIFT

A flight of G-VFIT from Atlanta to Heathrow, and its HFDL communications – visualized by GEPHI.

Gephi does it

Each communications has a structure. Visualization reveals this structure. This is also valid for HF communications with its networks with different stations, (even moving) locations, hierarchy …

Recently, I made my first steps with free visualization software GEPHI to get a deeper look into some aeronautical networks. The graph at the top shows the gephi’ed result of 125+ HFDL messages, transmitted by a flight of G-VFIT from Atlanta to Heathrow. I monitored six HFDL channels in parallel, one channel from New York, two from Shannon, and three from Reykjavik.

Each point represents a message, tagged by its time in UTC. The positions of the points are geo-referenced, as I used HFDL messages containing these information.

Wheras the longitude’s positions are to scale, their latitude’s positions had been spread for better reading.

This visualization shows that Reykjavik on 6.712 kHz did the main work. But it is surprising that the first contact just leaving the U.S. coast was made with Shannon, and not with nearby New York.

GEPHI also helps in visualizing the hiearchy of networks, see screenshot below:


In the Russian Aero Net on 4.712 kHz, Rostov plays a pivotal role.

Here the strength of the connecting lines and the position of the city’s names represents to hierarchy of this network, i.e. who is calling whom, and how often. There are several strongholds like Rostov, Yekaterinburg and Samara, but also some mere outposts like Novosibirsk and Syktyvkar.

This picture isn’t geo-, but social-referenced, to say so: you know that e.g. Chelyabinsk on the left is geographically situated east of Rostov. You may also geo-reference these data, turn it into a kml file and see it in Google Maps of Open Street Map. If the co-ordinates are correct, zooming will take you exactly to the feeding point of each of their Nadenenko dipole, see below …

The above visualized hierarchy has been changed here into a geo-referenced kml file, opened in Google Earth.

There are many more applications of such a great tool for visualization which will further enrich monitoring.

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