Tag Archives: Tutorials

Unlocking Rare DX Treasures with SDR-Console’s Powerful Data File Analyzer Tool

Finding Rare DX with the Data File Analyzer

By Don Moore

Don’s DX traveling stories can be found in his book Tales of a Vagabond DXer

I’ve been a real jack-of-all-trades in my over five decades of DXing. I began with SWBC (shortwave broadcast) but soon branched out to medium wave and voice utility. Later I added longwave beacons and more recently I’ve gotten into digital utility stations. My goal has always been to log lots of different stations from lots of different places. And the rarer they are, the better.

For SWBC and medium wave stations, as well as scheduled utility broadcasts such as marine and aeronautical weather reports, the DXing process is simple. You tune to a frequency at a time when a station is scheduled to be on the air. It’s either there or it’s not there. If it’s not there then maybe propagation isn’t right or maybe your antenna/receiver setup isn’t the best for that frequency band or the station’s power level. You tune away to find something else with plans to try again another day.

But it’s not always that easy. Most utility stations do not have fixed schedules and only come on as needed. The best example of that is two-way marine, aeronautical, and military voice communications.

In eastern North America, tune to 8906 kHz anytime from late afternoon until morning and set your receiver to USB mode. You’ll probably hear empty static at first but it’s unlikely that more than ten or fifteen minutes will pass before you’ve heard some aeronautical traffic. The frequency is assigned for communication on the North Atlantic and is heavily used by aircraft communicating with New York Radio, Gander Radio (Newfoundland, Canada), and Shanwick Radio (Shannon, Ireland). If you keep listening, the frequency will probably be occupied around 25% of the time. Wherever you are in the world, there are a few heavily used air frequencies like 8906 kHz and listening to them can be fascinating. But I want to log more than just a few easily heard stations.

Sticking to aeronautical DX, there are many assigned frequencies for different regions and air routes around the world. But propagation to those distant areas is unpredictable and less-used routes have fewer flights. Fewer flights mean less radio communication and more empty static. The most interesting frequencies may only see traffic a few times a week.

Hearing the rarest voice utility DX requires listening to lots of empty static just to get a brief DX catch. For years my process was simple. I would set my receiver to an interesting frequency and leave the tape recorder running while I sat nearby listening and doing something productive. I got some very good DX over the years that way. But I don’t want to think about how many long hours of empty static I listened to in order to get that DX.

 

SDRs offered some improvement. Instead of audibly monitoring a specific frequency I could now make a spectrum recording that included a band of interest, say the 8815 to 9040 aeronautical band. During playback I could visually monitor the SDR waterfall for interesting signals. That works. But watching an SDR waterfall scroll by for three or four hours gets tedious quickly.

(When I refer to SDRs, I mean ones consisting of a small box that is connected to and controlled from a computer using a software program. None of this applies to models such as the Malachite line or the Icom IC-R8600, which use SDR technology inside but mostly function as a traditional receiver.)

Finding a Better Way

That better way is, I think, one of the most exciting DX tools out there – the Data File Analyzer in the SDR-Console program. Since I learned about it a few years ago, the Analyzer has gotten me all kinds of catches that I probably wouldn’t have gotten otherwise. Let’s start with an overview and then dig into the how-to.

SDR-Console is one of the better-known SDR programs and it works well with most of the common SDR radios on the market, including the Airspy, Elad, Perseus, and SDR-Play models. Here’s what the main window looks like:

The Data File Analyzer is a second window that produces a scrollable waterfall display for the entire length of an SDR spectrum recording. The display is similar to a standard waterfall with frequencies along the bottom and times along the side. However, there is also a scroll bar on the right side for browsing through the entire length of the recording. Instead of watching a four-hour spectrum recording slowly roll by in real time, I can scroll through the window looking for DX.

And this is what makes the Data Analyzer really useful. When I spot an interesting signal, I click on it and that causes the main window to start playing at that time and frequency. Now going through a four-hour spectrum recording takes from a few minutes to around half an hour, depending on how much DX I find.

Here’s a closeup of part of that same screen of spectrum recording made on 24 October 2024 at a DXpedition in western Pennsylvania, USA.

“A” marks a short exchange between an aircraft and Ndjamena Radio in Chad on 8894 kHz. “B” is Niamey Radio in Niger on 8903 kHz. “C” is Gander Radio on 8891 kHz. Just to the left of that is a string of digital signals. “D” is New York Radio on 8918 kHz. Again, there is a string of digital signals just to the left. Finally, “E” is communication from Dakar Radio in Senegal and Sal Radio in the Cape Verde Islands on 8861 kHz. I caught four African aero stations in just four-and-a-half minutes. I could also show you long stretches of time when there was nothing interesting coming in. With the Data File Analyzer I was able to visually find and focus on the DX and not waste my time with the empty static.

Here’s another image taken at the same DXpedition. Notice the three transmissions between 8820 to 8845 that seem to be mirroring one other.

That turned out to be Flightwatch Brisbane, the Australian regional aeronautical network. It uses multiple transmitter sites on 8822, 8831, and 8843 kHz to cover the entire country. I had never logged it before and I doubt I would have found it if DXing in the traditional manner.

The How-To

Here I’m going to assume that you already have SDR-Console installed and know the basics of how to use it, including making spectrum recordings. (If not, see the links at the end.) This article was written using version 3.4 of SDR-Console. Some of the functionalities described are not in earlier versions, so upgrade if you are not up to date. And I should point out that while you can do this on a single monitor, it works more smoothly if you have a dual monitor setup and can put each window on a different screen. Continue reading

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The SDRplay RSP2 on Linux: a step-by-step guide

The SDRplay RSP2

Many thanks to Jon Hudson with SDRplay who recently shared the following video by Kevin Loughin which details the installation and operation of of the RSP2 on Linux. Kevin has written scripts that make the installation process more accessible to those not as familiar with Linux.

According to Kevin, this will run on Ubuntu 16.04 and other Debian-based Linux distributions.

Check out Kevin’s video below (or on YouTube). Kevin also published a step-by-step guide on his blog.

Click here to view on YouTube.

Click here to read step-by-step instructions on Kevin’s blog.

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Running SoniqWare SG-1 on a Windows PC

sg1-gui-fordocRecently, I posted a video showing how @LondonShortwave uses the GarageBand plugin, SoniqWare SG-1, for noise reduction. Since GarageBand is an Apple application, I didn’t believe SoniqWare SG-1 would work on a Windows PC, but SWLing Post reader Jeff Benedict (KB7AIL) writes:

“I run Mac OSX and GarageBand so it’s not really a concern of mine but, according to the documentation, SG-1 is compatible with Windows sound processing applications.
Here’s the documentation from SoniqWare:

From:  http://www.soniqware.com/pdf/SoniqWare-SG-1.pdf
p. 17

System Requirements
• Microsoft Windows XP/Vista,
• Mac OS X 10.5/10.6,
• 512 MB RAM,
• VST, VST3, or AU compatible host software

An explanation of the VST and a list of applications for Windows which are compatable with VST plug-ins:

http://en.wikipedia.org/wiki/Virtual_Studio_Technology

Of course, this comes with the caveat that I do not run any version of Windows or any of these sound processing applications so YMMV.

A short explanation of the different formats for sound processing plug-ins:

http://support.pluginboutique.com/knowledgebase/articles/51119-interface-types-explained-vst-rtas-au-etc-

Many thanks, Jeff, for the tip!

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Shortwave noise reduction via GarageBand plugin

sg1-gui-fordocMany thanks to @LondonShortwave, on Twitter, who made a video showing how to use a GarageBand plugin to filter noise out of shortwave audio in real time. He describes this on his YouTube channel:

“I recently discovered a Mac AudioUnit plugin called Soniqware SG-1 that allows real-time noise filtering based on a brief noise sample (sometimes referred to as the “noise profile” or the “noise fingerprint”). This video shows it being applied to shortwave radio signals, which I believe is a first, as I have been unable to find anyone else who has already done it. In a number of cases, it turns laborious DXing into armchair listening.

The antenna used in these experiments is a Wellbrook ALA1530SP-1 and is positioned indoors. More information is contained in the first few seconds of the video.”

Click here to watch the video on YouTube.

Note that GarageBand is an application only available on the Mac OS X platform. Fortunately, it comes free with every new Apple computer purchase. You can find the Soniqware SG-1 spectral noise gate plugin by clicking here.

Be sure to follow @LondonShortwave on Twitter: http://twitter.com/LondonShortwave

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How to decode WBCQ’s digital message

Last night, WBCQ’s sent a digital message about ten minutes before the end of the Allan Weiner Worldwide show. If you missed the broadcast, no worries; we recorded the show, and you can download the audio (below) to try decoding the message for yourself.

The digital message can be decoded using a variety of free software packages. The package we used–and which we use for many other digital modes–is FLDIGI, which can be found at http://www.w1hkj.com/Fldigi.html.

Downloading and installing FLDIGI is straightforward. But although this is a simple program, there is a slight learning curve involved.  Below, we explain how to use FLDIGI to decode the message.

1. Download the mp3 recording by clicking here (right-click, then save file).

2. Download and install FLDIGI.

Screenshot of digital mode being selected in FLDIGI. Click image to enlarge.

3. Launch FLDIGI and tell it that you wish to decode the digital format MFSK-64. Do this by selecting the menu items “Op Mode” –> “MFSK” –> “MFSK-64.”

4. Play the audio so FLDIGI can decode the message.

There are a few simple ways to play the audio:

  • If your computer has a built-in microphone, simply play the pre-recorded audio file from an mp3 player with a built-in (or amplified) speaker. Hold the speaker near the computer’s microphone. FLDIGI can decode the digital signal from the computer’s buit-in microphone if the mp3 player volume and microphone gain are adequate. FLDIGI is reasonably forgiving, but you should try this in a low-noise environment.
  • Better yet, if you have a way to feed the audio directly from your mp3 player into the line-in (or microphone input) on your computer–say, with a shielded audio patch-cord–this will insure a clean signal into FLDIGI. Note that you should lower the volume of your mp3 player to do this. In some cases, you can actually damage your sound card if you feed it audio at a high volume.
  • Another method would be to play the mp3 file on your computer and use a program such as Virtual Audio Cable to link the audio to FLDIGI.

FLDIGI capturing the digital message and decoding. Note the solid block of color in the waterfall display. Use your pointer to click in the middle of this block in order to tell FLDIGI where to decode. Click image to enlarge screen capture.

Note that in our recording we include several seconds of normal audio before and after the digital message. When you watch the “waterfall” display on FLDIGI, you will see a solid block of coloring indicating the digital message when it begins (see screenshot on right). When the hosts are talking, this block will not be visible.

5. When the digital message begins, use your pointer to click in the middle of the block of color that represents the digital message in the waterfall display of FLDIGI. This tells FLDIGI where to find the digital message in the audio.

6. Your decoded message will appear in the text area of FLDIGI (as in the screenshot).

Image of decoded message as an HTML page. Note that copy was excellent, save one small error in the text. These minor errors are fairly normal in a digital broadcast. Click to enlarge.

7. Copy the decoded text to your PC’s clipboard, and paste into Notepad (or Word, OpenOffice, etc) and save the file as HTML by giving it a “.htm” or “.html” file extension.

Now the message should appear.

See, that wasn’t so difficult! This digital message could be decoded without purchasing any special software or other accessories. Most of us have everything we need to decode the bulk of the digital messages on the shortwave bands–and there are many, many more out there.

Please leave a comment if you successfully decoded this message, or if you have any other tips for decoding it.

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