Monthly Archives: July 2019

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.