Author Archives: DK8OK

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 …

2,5+ million of Field Strength Data from ITU

Tehran-Norddeich_1983-1989_15K1MHz_3D1

Seven years of hourly field strength data of a transmitter in Tehran/Iran, received at Norddeich/Northern Germany. You clearly see the influence of time, day, season and solar activity.

 

The International Telecommunications Union recently published many information for free, which had been locked for years behind an often impressive cash house or had been available just for a few blessed.

Among these information is a bonanza of 2,5+ million of normalized field strength data from the years 1969 to 1993. This time covers two solar cycles and by far doesn’t provide insights of only historical interest: You e.g. may visualize some circuits to see the influence of day, time and solar activity at a glance. And you may use this data to analyze some dependence between field strength and solar/geomagnetic activity.

As these data so far hasn’t attracted any interest of ham radio magazines, we are just at the beginning to make use of it. Join in!

The diagram at the top has been made with QtiPlot software. The same software has been used to visualize solar and geomagnetic WDC data, obtained from GFZ Potsdam – see diagram at the bottom.

Kp_vs-Flux_2

Solar flux (F10,7) vs. geomagnetic activity (Kp index), 1969-1993.

 

SDR-Transceiver-Netz des DARC e.V.?

Weiter gibt es Ungereimtheiten beim seit einigen Jahren groß angekündigten Remote-Transceiver-Netz des DARC e.V., das seine Fördermitglieder schon mit jeder Menge Geld vorfinanziert haben. Offenbar wird es nur von zwei Personen getragen, wobei man für die komplette Software sogar auf ein Nicht-Mitglied des “Bundesverbandes für den Amateurfunkdienst” zurückgreifen musste – der somit einem Kreis entstammt, der das Netz nach dem Willen des Vorstandes nicht einmal wird nutzen dürfen …

Den Stand der Dinge habe ich nach öffentlich zugänglichen Informationen in der Juli-Ausgabe der Fachzeitschrift “Funktelegramm” zusammengefasst. DARC-Noch-Mitglied DL7AG hat diesen Text mit Erlaubnis von Joachim Kraft, Herausgeber und Chefredakteur des “Funktelegramm”, auf seine Website gestellt.

Wie inzwischen weiter bekannt wurde, hat allein das DARC-Mitglied des Entwickler-Duos, Helmut Goebkes, für das Projekt 25.382,70 Euro erhalten. Der Auftrag wurde ihm freihändig und ohne Ausschreibung vom DARC-Vorstand zugeschoben. Der Software-Entwickler Stefan Görg – kein DARC-Mitglied – ging hingegen leer aus. Er hatte auch niemals Geld verlangt.

Überdies nehmen die Ungereimtheiten innerhalb des DARC darüber zu, wer dieses Netz eines Tages überhaupt wird benutzen dürfen: nur DARC-Mitglieder oder jeder Funkamateur? Der DARC-Vorstand möchte es exklusiv seinen zahlenden Mitgliedern zur Verfügung stellen – wobei der Zutritt zum Verein nicht diskriminierungsfrei ist. Viele andere Funkamateure – darunter sogar Betreiber des Netzes! – teilen jedoch diese restriktive Sicht des DARC-Vorstandes nicht und setzen sich für einen wahren Ham Spirit ein: „Die Ausbreitungsbedingungen sowie die eigene Aussendung können mit der neuen Technologie von Funkamateuren aus der ganzen Welt beobachtet werden. Die intensive, ja wissenschaftliche Auseinandersetzung mit einem großen Frequenzspektrum ist damit jedermann möglich“, heißt es etwa von den Betreibern aus Bad Honnef, die sich im Gegensatz zu ihrem Vereinsvorstand ein für alle Funkamateure weltweit offenes System wünschen.

Noch aber ist es nicht so weit. Denn, so Hardware-Mann Helmut Goebkes: “Der Aufbau der Infrastruktur eines solchen Vorhabens erfordert schon noch ein bisserl mehr als nur irgendwo eine Hardware ins Netz zu stellen.”

Beispielsweise erfordert es eine Klärung der amateurfunk-genehmlichen Rechtslage, die der DARC auch im vierten Projektjahr immer noch nicht erreichen konnte. Der erhoffte sich übrigens für seinen Verlagsableger ein Geschäft mit der Hardware und warb mit großer Tröte dafür, dass die Transceiver über die DARC GmbH beziehbar sein werden. Auch das hat sich trotz vollmundiger Ankündigungen noch nicht materialisiert.

Haken soll die Inbetriebnahme des Transceiver-Netzes zudem noch daran, so DARC-Mann Goebkes, dass “entsprechende sendefähige Breitbandantennen (!) am Aufstellort vorhanden sein” müssten. Aber nur schwer vorstellbar, dass dem nach einer langen Bewerbungsphase für die 15, 18 oder 19 Standorte nicht ist. Denn, so der DARC, diese mussten sich ja in einem Bewerbungsverfahren unter den mehr als 1.000 Ortsvereinen “durchsetzen”. Und selbstverständlich wird eine der Bedingungen für den ersehnten Zuschlag gewesen sein, für die entsprechende Infrastruktur zu sorgen – wie sie im übrigen schon an vielen Standorten vorhanden ist.

 

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]

Murmansk FAX: 6.328,5 kHz, new Frequency

Murmansk_6328k5_120_576_1kShift_20170609_0450

Tune into 6330,4 kHz LSB, to get the right black/white frequencies, centered at 1.900 Hz. Shift 1.000 Hz, so 1.400 Hz = white, 2.400 Hz = black. 120 RPM/576 IOC, no APT! Received on June 9th, 2017, at 04:50 UTC.

Reports of the death of Murmansk FAX had been slightly exaggerated … After having searched for it in vain in 1Q/17, it now popped up on 6.328,5 kHz from former 6.445,5 kHz with an irregular schedule, namely at 03:30 UTC at one day and 04:50 UTC another day.

Just fair quality of both, conditions and transmitter, made it very difficult  to read the text in the upper part of this weather chart in Cyrillic, with just: Прогноз … 21 час [Prognosis … 21 hour …]. Receiver AirSPy & SpyVerter, decoder Wavecom W-Code.

Also received on June 1st, 2017, but starting at 03:30 UTC – same area, first half of the transmission heavily distorted by an RTTY signal, see below:

Murmansk_6328k5_120_576_1kShift_20170501_0330

Reception on June 1st, 2017, from 03:30 UTC on 6.328,5 kHz.

Iceberg Prognosis has been received on scheduled 8.444,1 kHz at 20:00 UTC on June 8th, 2017; see below:

8444k1_Murmansk_20170608_2000

Murmansk FAX with Iceberg Prognosis  on 8.444,1 kHz at 20:00 UTC on June 8th, 2017. Cyrillic texts not quite readable. Also received on May, 31st, 2017, same frequency, same time.

Not a trace on/near also listed 7908,8 kHz. It seems that otherwise commendable NOAA publication Worldwide Marine Radiofacsimile Broadcast Schedules is outdated regarding this station.

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!

 

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