Propagation Day by Day: CRI Kashi, 15.260 kHz

Signal strengths of CRI/Kashi, day by day, from 08:58 UTC to 09:58 UTC on the nine consecutive days March 15 to March 23, 2020; see text.

Propagation on HF differs from day to day. The nine diagrams at the top show the signal strengths of China Radio International’s Kashi transmitter, 500 kW, beaming to Romania; 08:58 UTC to 09:58 UTC from March 15 to March 23. The basic resolution (black grey points in the background) is 100 milliseconds, whereas the blue line marks the moving average with 601 points. The “moving average” can be best understood as a lowpass filter, revealing possible trends on a coarser scale. In this case, you cannot see such a trend.

If you compare a part of each transmission on a much finer scale, you even see sheer chaos, as the Figure below is showing:

All nine signal levels drawn together into one diagram (top), and a small part of it zoomed (bottom) reveals sheer chaos.

There seems to be no visible correlation on any scale in this case. There are other cases where, however, some correlation can be found – to which I will come back in some future entries.

The last diagram at the bottom of this pages shows a much more forgiving picture of the signal: the average level changes not more than ±4 dB between best and worst days. This so-called box diagram illustrates best the actual receiving quality of the broadcast, demodulated with an synchronous detector to largely avoid severe distortion by selective fading. The difference of deciles 90% and 10% marks the fading range, a key figure in describing the quality of reception – see “Ionospheric Radio” by Kenneth Davies [London, 1990/96, pp. 232].

The box plot shows very similar signal strengths, day by day. You should concentrate on their each center of gravity. You will also see that the distribution of the signals strengths relative to the center is not symmetrically, with a clearly visible advantage to the percentalge below the average strengths. THis will be covered in some future entry.

Analyzing signal strenghts, is an interesting tool to get to know more about propagation. I will continue this topic – stay tuned!

Receiver: Winradio’s Excalibur Sigma
Antenna: active vertical dipole (2 x 5 m) MD300DX
Software: V3 by Simon Brown, G4ELI, QtiPlot

Greyline enhancement

Signal level on 4750 kHz, observed over some hours: After s/off of Bangladesh Betar, People’s Broadcasting Station at Hulun Buir emerged, showing a peak just after their local sunrise

Today’s SDRs plus able software allow for some new insights into propagation. The figure at the top shows but one example: greyline enhancement. It follows the signal levels on 4750 kHz with a resolution of one second. Smoothing this cloud of points, reveals the more general course of signal level. Here we see, after sign off of Bangladesh Betar, the 10 kW transmitter of People’s Broadcasting Station at Hulun Buir coming up. Most interesting is its short-living enhancement just after sunrise at Hailar in China’s Inner Mongolia, squeezed at their borders to Russia and Mongolia.

This greyline enhancement can be observed regularily on frequencies under, say, 10 MHz: at sunrise at the transmitter’s site, first the F2 layer of the ionosphere is building up, being responsible of the signal of, here, about 5 dB. The lower and attenuating D-layer needs a bit more time to build up, leaving a short-living window for an enhanced signal.

This is to encourage also other HF aficionados to to use this technique.

Receiver: Winradio’s Excalibur Sigma
Antenna: active vertical dipole (2 x 5 m) MD300DX
Software: V3 by Simon Brown, G4ELI, QtiPlot and DX Atlas

1993: "Die Grenzen des Amateurfunks"

Ein freundlicher Leser stöberte in alten Heften der längst von zwei DARC-Leuten absichtsvoll zerstörten Fachzeitschrift “funk”. Er stieß dabei auf ein Editorial, das ich im Juli 1993 dort über “Die Grenzen des Amateurfunks” veröffentlichte. Ihr könnt es ihr hier nachlesen.

Diese Grenzen verortete ich schon damals hauptsächlich in der Betriebstechnik der Funkamateure sowie in falschen Schwerpunkten bei der Auswahl von Gerätschaften und Modulationsarten. An diesem Befund hat sich leider auch eine Generation später wenig geändert. Nur die Störungen, die uns damals schon das Leben etwas schwerer also notwendig machten, die sind nochmals stark angestiegen.

Bedauern kann man überdies, dass es heute keine Funk-Fachpresse mehr gibt, die in gleicher Weise wie die “funk” begeisternd und anregend über technische Innovationen berichtete, sie durchaus kritisch prüfte, Hintergründen – auch bei Besuchen der Hersteller bis hin in Tokio und Osaka – nachspürte, darüber professionell informierte und Monat für Monat lebhaft Werbung für unser Hobby auch unter jenen machte, die zunächst nur lose am Thema “Funk” interessiert waren. Viele von ihnen legten daraufhin ihre Prüfung erfolgreich ab, während nach erfolgreicher Zerstörung der “funk” die “Teilnehmerzahlen am Amateurfunkdienst”, wie der Begriff in aller offizieller Umständlichkeit lautet, kräftig gesunken ist. Unbedingt ein weiterer Erfolg, den sich der DARC ans Revers heften kann – gleich neben die Goldene Deppenraute mit Antenne und Brillanten 😉

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.
« Older Entries