Author Archives: DK8OK

CIS Time Signals on VLF

Locations, callsigns and starting times of the received VLF time signal stations, 25 kHz

On January 10, 2020, I did a round-up of VLF time stations from the Commonwealth of Independant States (CIS). They are controlled by the Russian Navy and start their main transmission on 25.0kHz. Then they change to a couple of four other VLF channels. See here for some detailed information in Russian. The diagram below shows a panorama of all received station (Khabarovsk in the Far East missing, as they skip transmission on the 10., 20. and 30. each month) on all frequencies versus time and signal level.

Five locations, six transmissions, five frequencies – this diagram puts it all together.

The diagram features a time resolution of 1s and has a resolution bandwidth of about 0.12 Hz. It is part of a 24h session, made with Winradio’s Excalibur Sigma SDR, active dipole MD300DX (2x5m) and Simon Brown’s software SDRC V3. This software delivers also the values for level over time, which were visualized and combined with QtiPlot software.

Only seemingly, Vileyka and Krasnodar are transmitting on two channels at the same time (from 07:06 UTC/11:06 UTC). This is not the case, but their transmitters show a bit wider signal in their first part of the transmission. Thus, the much weaker (ca. -30dB) “signal” at the same time, but 100Hz up, is some kind of sideband, but not the carrier!

You will see some variation of the carrier power, especially following sign on, but also during the transmission. This can bee seen with tenfold time resolution (i.e. 100ms) and magnifying the dB-scale, see diagram at the bottom as just one example. Fading can be largely excluded for several reasons, artificial characteristic of changes and VLF propagation during short periods among them.

Under the microscope: This rise of 1.5dB of the carrier is part of the workflow of switching on/tuning the transmitter. There are many such details, and they may differ from transmitter, location and performance. Such details might be used for “fingerprinting”.

P.S. The map at the top was made with free software Tableau Public. The locations are geo-referenced, and a satellite map as background will you lead directly to the antennas. Please try this here.

FAX from Shanghai: Pacific Pressures

This FAX broadcast was new to me and received on December 16, 2019 at 08:20 UTC on 16557,1 kHz. It was transmitted via Shanghai Coastal Radio, presumably directed into the Pacific, of which it shows the 48h surface pressure.

It was demodulated from a 25 MHz wide HF recording over 24 hours. This recording was made with Winradio’s G65DDCe Sigma SDR, connected to an active vertical MegaDipol MD300DX (2 x 5 m), and decoded with Wavecom’s W-Code. The recording was scheduled with software SDRC V3 by Simon Brown, and directed via USB3.1 to a 20TB hard disk, WD Duo Book. The resulting one file was 8TB, format WAV RF64.

It was also played back from this hard disk, also via USB3.1. Doing so, it is most remarkable that this setup worked smoothly without any glitches which would promptly have been seen at such a time-critical mode like this FAX., 120/576. So, this reception is also a proof that one can work smoothly with such ‘big data’ even on a hard disk – and not only on expensive SSDs. A FAX transmission is that sensitive that you even see a very weak echo (best seen of the big vertical black stripe at the right which echoes from around 115° East). This originates from a mixed short/long path reception. The strong short path’ flight time is 28.7ms, whereas the weak long path needed 104.7ms. As one FAX line covers 500ms, you can easily measure the delay of roughly 80ms, almost exactly matching the difference of long and short path.

The screenshot has been left un-retouched.

DARC: Rauswurf von DK8OK “satzungswidrig”

Im Jahre 1992 warf mich der Deutsche Amateur Radio Club e.v. (DARC) in überaus hinterhältiger Weise und ohne jede Vorwarnung aus seinen Reihen. Angeblich, so die Halluzination des damaligen Distriktsvorsitzenden in Niedersachsen, hätte ich dem Verein “geschadet”. Nichts weniger als das – und weder er, noch im weiteren Verlauf des Verfahrens der damalige 1. Vorsitzende des DARC konnten auf Vorhalt selbst vor Gericht auch nur einen einzigen Schaden benennen: alles wirre Gesichte. Denn es waren, im Gegenteil, genau auch diese Leute, die dem Verein und dem Amateurfunk massiv schaden sollten. Er verlor seitdem auch deshalb annähernd die Hälfte seiner Mitglieder und stopfte schon bisher rund eine Million Euro in die Taschen von Spitzenfunktionären. Hier allerdings wurde, natürlich, kein Schaden festgestellt.

Dennoch unterblieb eine immer wieder geforderte Rehabilitierung meiner Person. Der heutige Distriktsvorsitzende Niedersachsen zieht sich darauf zurück, dass “eigentlich” ja der DARC-Gesamtvorstand mich rausgeworfen hätte. Der aber reagiert auf dieses Ersuchen nicht. Seit Jahrzehnten nicht.

Das nun aber tat Dr. Erhard Blersch, DB2TU, als Vorsitzender des DARC-Distriktes Württemberg in seinem Rundspruch vom 22.12.2019. Demnach sei dieser Rauswurf eine (und bei weitem nicht die einzige!) “Leiche im Keller des DARC”. Und, konsequent: “Zeit wird es auch, Nils Schiffhauer, DK8OK, zu rehabilitieren.” Ich hätte “in den letzten Jahren und Jahrzehnten sehr viel Positives für den Amateurfunk geleistet.” DB2TU fasst klipp und klar zusammen:
“Der Ausschluss von Nils war satzungswidrig.”

Das nun lag zwar seit fast 30 Jahren auf selbst der flachsten Stirn. Diese Selbstverständlichkeit aber endlich mal öffentlich eingestanden zu haben, ist innerhalb des DARC nicht nur mutig (Erhard wurde ja nicht nur dafür gemobbt, sondern überhaupt für seinen Einsatz für einen transparenten, modernen und diskriminierungsfreien DARC), sondern könnte auch wieder Bewegung in den “Fall DK8OK” bringen, der eigentlich ein “Fall DARC” ist.

Dass man die damals Verantwortlichen, so sie noch im DARC Mitglied oder gar Ehrenmitglied sind, hierfür mit der “Goldenen Deppenraute mit Brillanten und Antennen” auszeichnen will, ist freilich erst nur ein Gerücht …

Looking at Things: Elad FDM-S3 [beta]

The new FDM-S3. Made in Italy, by ELAD.
19.7 MHz alias-free for receiving, recording and playing

As seen from now, ELAD’s FDM-S3 is still to come. It features a 16 bit SDR with up to 24 MHz bandwidth (19.7 MHz alias-free) for receiving, recording and playback. It will become the great brother of the renowned FDM-S2 of also 16 bit, but with just 5 MHz alias-free bandwidth which was State-of-the-Art when this radio hit the market. Still, this remarkable FDM-S2 sets the standard in its price class.

The file format of the S3 is the same as with the S2, so Simon Brown’s software SDRC V3 works on S3 files also (see screenshot at the bottom). This opens V3’s File Analyzer plus up to 24 demodulators when playbacking files. SDRC V3 will support also live reception when the radio will be more widely available.

Simon Brown’s software SDRC V3 is reading FDM-S3’s files also.
The FDM-S3 cover the whole FM band. Here shown with receiving six stations in parallel, including demodulation and RDS deocding. The lower half of the the spectrogram shows the performance without pre-amplifier, the upper part with pre-amplifier switched in.

Airspy HF+ Discovery & Spurious Signals – Much Ado about Nothing

Worst case: Those very few and low-level spurious signals of the “Discovery” disappear completely in the atmospheric noise after you connect an antenna – leaving even faintest stations in the clear.

There had been some discussion about the “real” performance of the brand new Airspy HF+ “Discovery”. It is not only my experience that this great little SDR is a perfect performer at a ridiculous low price.

The discussion focuses on “spurious signals”. I measured them with the Winradio SIGMA as spectrum analyzer, compared it to the two past Airspy HF+ models, plus Discovery, and did some work on how this effect might touch reception.

The result is clear: this discussion in the Ivory Tower is “Much Ado about Nothing”. You may read more about method & findings, with many diagrams, in this PDF.

3 x CW: Kagoshima Fishery Radio, JFX

Parallel DXing: JFX on 6421,5 kHz, 8690 kHz and 12704,5 kHz

Morse Code or CW has become rare among professionals (in the West). But there is a busy net of small Japanese Fishery Stations literally pounding the brass. One of them is Kagoshima Radio, JFX. They are not daily heard in Europe, but a combination of receiver Winradio Sigma, active antenna MD300DX (2×2.5 m, vertical) and SDRC V3 software did the trick even under this grim summer propagation. See screenshot above, from 24 hours’ recording of 25 MHz HF. All channels clearly readable – as far as the expressive handwriting (see detailed screenshot at the bottom) of their CW allows for … Yeah: CQ CQ DE JFX JFX QRU QSX 6 / 8 /12 MHz K

First part of the CQ call of JFX in good ol’ hand-made CW … from 12704.5 kHz

New Dimensions: Airspy HF+ Discovery

A big achievement: The new Airspy HF+ “Discovery” is even smaller than the Airspy HF+.

From start, Airspy SDRs with their unique block diagram received an overwhelming reputation in the challenging HF bands. They feature a high dynamic range in a small case – and even match a small wallet, too. Now their new “Discovery” enters new dimensions in every respect. The photo on top shows the small black beauty in the foreground compared to the already known Airspy HF+ in the background.

It is already running here with e.g. SDR# and SDRC V3 software, see below. The very first impression is that of an SDR with an exceptionally low noise level and, thanks to its tracking filters, a matching dynamic range. Alas, being a bit short in time these days, I hope to come back with some more solid comments in due time.-

A first look onto the 19m broadcast band shows the low noise level plus the high sensitivity, resulting in a great SNR.

Specified to receive already from 0.5 kHz, it is a true performer also on VLF – see screenshot below with reception of US Navy Cutler/Maine on 24 kHz, about 35 dB down of Germany powerhouse DHO38 just 600 Hz below. Reception: August 2nd, 2019, 14:38 UTC in Germany with vertical active dipole (2×2.5 m) MD300DX.

Fine VLF reception of MSK signal MIL-STD-188-140 from US Navy in Cutler/Maine on 24 kHz. Horizontal lines are from thunderstorms, and the “hill” peaking near 34.5 kHz is local noise.

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.

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