Tag Archives: Test

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.

R&S EB500: The Über-SDR

EB500_GUI1

It’s easy to look into the future of hobby receivers: just look on what the professionals are doing! Since the days of AEG-Telefunken’s E-1800, I do follow this advice. Where are the professionals yet better, and what may the amateur world see at their receivers the coming years? Hence, I was glad to test Rohde & Schwarz’ EB500 for some weeks; plus their professional decoder GX430. Even more, as I visited them in Munich and talked with some of their engineers.

Alas, the resulting paper with 15 screenshots is written in German. But surely Google Translator will be your friend.

Wie sieht die Zukunft der Hobby-Empfänger aus? Diese Frage interessiert mich seit den frühen 1980er-Jahren, als ich den damaligen weltbesten Receiver testete, den E-1800 von AEG-Telefunken. In welchen Punkten sind die Profis besser, und was können wir in der Hobbypraxis damit anfangen? Schließlich: Was kommt auf uns in den nächsten Jahren zu? Deshalb freute es mich, den EB500 von Rohde & Schwarz für ein paar Wochen zum Test gehabt zu haben – zusammen mit dem Profi-Decoder GX430. Mehr noch, denn ich konnte einige der Entwickler in München sprechen und so auch einige Hintergründe erfahren.

Das deutschsprachige Manuskript des Tests: hier klicken.