Tag Archives: Test

SDR-Netz des DARC e.V.: Rauschende Ergebnisse

R2T2_Braunschweig_ANT1

Einfach vergleichen: Oben CHU 14.670 kHz an einem Remote-Standort des DARC e.V., unten zur selben Zeit an einem durchschnittlichen Standort.

Aus den Mitteln seiner “Mitgliedschaft Pro” bestellte der DARC e.V. im Jahre 2014 sein Web-SDR-Transceivernetz. Es soll seinen Mitgliedern “weltweiten Funkbetrieb aus dem heimischen Shack ermöglichen”. Jeder der über 1.000 DARC-Ortsvereine war aufgerufen, sich als einer der zwölf Standorte zu bewerben. Gesucht waren solche Locations, die vor allem einen störungsarmen Empfang und gute Antennenmöglichkeiten bieten – was der Funkamateur in der Stadt eben nicht hat.

Obwohl die R2T2 genannten Geräte für über 25.000 Euro längst ausgeliefert wurden, ist es bedauerlicherweise merkwürdig still um dieses schöne Projekt geworden; auch die zugehörige Yahoo-Newsgroup scheint nicht mehr ansprechbar zu sein.

Wie also ist der von außen (ich bin kein Mitglied des DARC e.V., begrüße aber dieses Vorhaben uneingeschränkt!) sichtbare Stand des Projektes?

Um das zu erkunden, habe ich am 20.12.2017 alle verfügbaren Remote-Standorte (sechs, und die auch lediglich empfangsseitg ansprechbar) mit dem Empfang “im heimischen Shack” – leider einer ziemlich durchschnittlichen Location – verglichen.

Die ersten Ergebnisse habe ich in einem PDF zusammengefasst, das ihr hier unter R2T2 herunterladen könnt.

Diese Versuche wurden zur Vervollständigung des Bildes fortgesetzt – siehe unten. So nahm ich am  21.12. um 07:45 UTC einen Vergleich auf 17.950 kHz vor, wo bei mir der Rundfunksender China Radio International/Kashgar mit einem SNR von gut 31 dB einfiel: bis auf ein sehr schwaches und praktisch unverständliches Signal vom Remote-Standort Wiblishauserhof war auf den anderen Remote-SDRs des DARC so gut wie nichts zu hören, zum Teil wegen (lokaler?) Störungen. Unten der Vergleich meiner Station (unten)  mit dem bayerischen Remote-SDR (oben).

r2t2_Bayern_17950

Vergleich China Radio International, 17.950 kHz: oben der bayerische SDR des DARC-Remote-Netzes, unten dieselbe Station zur selben Zeit am Standort DK8OK.

Einen weiteren Test unternahm ich am 26.12.2017 gegen 12:30 UTC auf 1.521 kHz (CRI/Kashgar, Nähe zum 160-m-Band) und auf 4.800 kHz (China National Radio 1/Golmud). Diesmal erfolgte der Vergleich an einer Aktivantenne (statt der Quadloop)  meinerseits, die bei beiden Stationen eine Empfangsqualität von SIO 253 bot.
In beiden Fällen war das Ergebnis ähnlich: von den sechs verfügbaren Remote-SDRs konnte drei die Stationen überhaupt nicht empfangen. Eine weitere lag knapp über der Hörschwelle, Schöppingen zog fast gleichauf, während Wiblishauserhof in etwa Gleichstand mit meiner Anlage bot – als einzige Station von zwölf bezahlten/geplanten. Für gut drei Jahre Bauzeit und über 25.000 Euro Investment ein Befund mit durchaus Luft nach oben.

Eine Fortsetzung derartiger Vergleiche scheint daher solange sinnlos, wie das DARC-Netz nicht erweitert bzw. Standort/Antennen/SDRs entscheidend geändert werden.

Was hingegen engagierte Hobbyhörer ehrenamtlich und mit allein privatem Geld im Gegensatz zum “Bundesverband für den Amateurfunkdienst” der staatlich geprüften Hobbyfunker zustande bringen, zeigt – ebenfalls mit 14-Bit-SDRs – das leistungsstarke Kiwi-Netz.

Airspy HF+: What you hear, is what you get

 

 

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It has been dubbed “game changer” and indeed, the Airspy HF+ is a completely other animal of software-defined radio, or SDR. Developed by Youssef Touil plus team and produced by ITEAD, it sells for just US-$ 199 right from factory at Shenzhen, China. This is considered the middle class of SDRs, starting with cheap USB sticks under 10 US-$ and scratching the mark of nearly US-$ 5.000 with Winradio’s WR-G39DDC. This one also marks the transition zone from what even an engaged hobbyist allows himself to spend to the truly professional receivers of e.g. Rohde & Schwarz and Plath. To make it clear: You may achieve professional results at each price tag, even from an RTL & its clones, as Carl Laufer’s excellent blog shows almost daily.

The Serious HF-DXers in mind

Airspy HF+ has been developed with the serious HF (shortwave) listener in mind. In this field it sets new standards regarding sensitivity, dynamic range and noise. Its stunning performance is achieved by a revolutionary approach and a careful layout of the hardware, housed in a sturdy metal case.

I don’t want to add another explanation of this concept (my test report will appear in 1Q/2018 in “Funkamateur“) but just offering the pure stuff. Some first twelve audio examples should give you a truly hands-on impression to answer the one and only question: How loud does this animal roar?
Therefore, I compared about 100 often vastly different situations on HF between Elad’s FDM-S2 (US-$ 525) and Airspy HF+. From this collection, I carefully selected some first twelve examples to cover the needs of the casual listener as well as the hard-core DXer.

All audio clips were recorded in parallel with a 20 m quad loop as antenna, feeding a professional 1:2 HF splitter by Heros. Software used was free SDR-Console V3 by Simon Brown – thanks.

Dare to make use of your own understanding

First, you read a description of the case, followed by a recording with FSM-S2 and then by Airspy HF+. Each of both examples has been recorded with exactly the same bandwidth, mode, AGC etc. which had been optimized for that situation. You must listen to these audio clips with headphones to scrutinize the mostly very small differences. Aim you ear towards fading, noise and intelligibility.
This is not a traditional test, where the master of ceremonies masticates the results for you. It’s for the truly demanding DXer, “to make use of your own understanding” (Kant, 1784). Just a hint: weak stations make the difference!

Fasten your Headphones: The Examples

The audio examples are roughly sorted from easy to difficult signals. They were made in the first week of December, 2017.

Radio Sultanate of Oman, Seeb/Oman
15.140 kHz, 100 kW, AM, 5.350 km, 14:10 UTC, strong/free channel, SAM, 10 kHz bandwidth. Keep an ear on noise and slight fading!

 

Xinjiang People Broadcasting Station, ÜrümqiChina
4.500 kHz, 50 kW, AM, 5.500 km, 14:24 UTC, fair to good/free channel, SAM, 9 kHz bandwidth.

 

Bangla Desh Betar, Savar/Bangladesh
4.750 kHz, 100 kW, AM, 7.300 km, 14:29 UTC, fair/free channel, SAM, 9 kHz bandwidth.

 

Xizang People’s Broadcasting Station, “Holy Tibet”, Lhasa/China
6.025 kHz, 100 kW, AM, 6.850 km, 16:00 UTC, fair/strong broadcaster 5 kHz up, ECSS-L, 2,8 kHz.

 

Bangkok VOLMET, Bangkok/Thailand
6.676 kHz, 10 kW, USB, 8.800 km, 16:10 UTC, fair/free channel, USB, 3 kHz bandwidth.

 

Gander VOLMET, Gander/Newfoundland Canada
10.051 kHz, 10 kW [?], USB, 4.400 km, 15:20 UTC, weak to fair at fade-in/free channel, USB, 2,8 kHz bandwidth.

 

Myanma Radio, Yangoon/Myanmar
5.985 kHz, 50 kW, AM, 8.250 km, 01:00 UTC, weak to fair/interference from upper channel, ECSS-L, 5,5 kHz bandwidth.

 

Radio Aparecida, Aparecida/Brazil
6.135 kHz, 10 kW, AM, 9.900 km, 00:30 UTC, fair/free channel, SAM, 3,5 kHz bandwidth.

 

Time Signal Station CHU, Barrhaven/Ontario Canada
3.330 kHz, 3 kW, USB with carrier, 5.900 km, 06:00 UTC, fair/fsome interference from digital station above, USB, 3 kHz bandwidth.

 

Time Signal Station BPM, Shaanxi/China
15.000 kHz, 20 kW, AM, 7.750 km, 09:00 UTC, weak/free channel, SAM, 5 kHz bandwidth. Occasionally echo from mixing short/long path, some CW echo (long path) is running into the next via short path.

 

China Radio International, Ürümqi/China
1.521 kHz, 500 kW, AM, 5.500 km, 13:00 UTC, weak at fade-in/free channel, SAM, 6 kHz bandwidth.

 

Auckland VOLMET, Auckland/New Zealand
6.679 kHz, 5 kW, USB, 25.800 km (long path!), 07:20 UTC, very weak/free channel, USB, 3,6 kHz bandwidth. Here headphones are a must!

 

 

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!

 

Steckt sie alle in die Tasche: Reuters “Pocket”

Reuter_Pocket

Burkhard Reuter mit seinem “Pocket”: Eine Entwicklung, auf die er stolz sein kann

Wo eigentlich bleiben die Weltempfänger? Die Spitzenklasse kommt heute nicht aus Japan und schon gar nicht mehr aus den USA oder aus Fürth, sondern aus: Dessau. Dort hat Burkhard Reuter unter anderem seinen Pocket entwickelt. Das ist ein Taschenempfänger, den es auch mit Sendeteil gibt. Seine Leistung ist absolute Spitzenklasse. Sein Konzept folgt einem ab initio selbst entwickelten und “Spectrum Based Signal Processing” genannten Algorithmus. Alles an diesem Gerät ist schlichtweg außergewöhnlich: von der Leistung über die Wertigkeit bis zum Preis. Für die Titelgeschichte der Mai-Ausgabe 2017 der Fachzeitschrift FUNKAMATEUR habe ich Burkhard Reuter in seiner Werkstatt besucht, mir seinen Weg und sein Konzept erläutern lassen sowie seinen Receiver auf Herz und Nieren getestet.

Where have all the world band radios gone? The most recent one – and probably the best ever produced – emerged out of the workshop of Burkhard Reuter (pictured above) from Dessau/Germany, the city of Bauhaus fame. For the cover story (May, 2017) of the German FUNKAMATEUR magazine, I visited him and did an in-depth test of this smart receiver, following his unique “Spectrum Based Signal Processing” algorithm. His Pocket turned out to surpass reception quality of each and every world band radio before, scratching the performance of even professional table top receivers. Some versions of it also include a ham radio transmitter (QRP). Already another modern classics from the Bauhaus city …

 

Airspy & SpyVerter: An Excellent Performer on HF

24ch

24 broadcast channels demodulated in parallel on shortwave – and Airspy plus SpyVerter do need just a quarter of PC’s power!

Always being interested in SDRs with remarkable HF performance, Airspy and the matching up-converter, namely SpyVerter, attracted me. It is a 10-bit SDR, covering 24 MHz to 1.800 MHz (just Airspy) plus 1 kHz to 60 MHz by help of SpyVerter (+120 MHz). Both come in solid metal cases.

I did test this combo in detail on HF, i.e. under 30 MHz. It proofs to be a sensitive setup with a surprisingly dynamic range, ending up in clear recpetion of up to a nearly 10 MHz wide band. This may be recorded and eventually played “as live”.

The test has been published on 19 pages plus 25 instructive illustrations, and the PDF can be dowloaded here. It is a real hands-on test in real practice. This includes also weak signal reception of data, demodulating and decoding of 24 HFDL airband channels in parallel, DRM and FAX decoding (KVM70/Honolulu) and reception of Auckland VOLMET von 6.679 kHz via long path.

The result ist simply stunning: if you are in search for a “low cost, high perfomance SDR”, that’s exactly is it. Yes – Youssef and his team advertise it with this claim, but it is one of the rare cases where such a claim meets reality. Be surprised, become convinced!

French version: Bernard Malet was so kind to translate the paper into French, merci!
Téléchargez ici, s’il vous plait.

Titan_SDR: New Approach in SDR, 40 Channels at once

DSC_night

With it’s TitanSDR, Italy-based company Enablia has a new approach in SDRs: This receiver delivers up to 40 demodulated channels in different HF bands.

Applications are numerous, e.g. checking GMDSS channels in different maritime bands (see above), monitoring many ALE channels at once, control broadcasters with all their parallel frequencies etc.

This paper delivers on 26 pages and with 44 illustrations a detailed hands-on explanation of this new approach. It is enriched with some audio clips. It shows real-world example of receiving brodcast, amateur radio and utility stations. And it assists you in setting up a couple of decoders at once to monitor many channels in parallel.

Caveat: Embedded multimedia content will only work with the most recent version of Adobe`s Acrobat Reader. And you have to save the PDF on your device (hard disk/stick), to make use of these multi-media.

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