Tag Archives: Digital Message

German regulators prohibit digital modes on broadcast bands

(Source: Kim Elliott via Richard Langley)

VOA Radiogram, 2-3 April 2016: BNetzA sagt nein!

New this weekend is the elimination of the digital text modes from shortwave transmitters in Germany.

The German regulator Bundesnetzagentur has ruled that the digital modes are not allowed in the broadcast bands. Because of this, there will be no MFSK32 on The Mighty KBC this weekend, because it uses a transmitter in Nauen, Germany. And, for the time being, there will be no DigiDX MFSK broadcasts on Channel 292, 6070 kHz, and Radio 700, 3985 kHz.

Listeners in Germany might want to note these arguments for the digital modes on the shortwave broadcast bands:
1) It is broadcasting, not point-to-point communication.
2) It can be received on any shortwave radio, even inexpensive portables with no SSB capability. (Software is required to decode the text and images, but this can be included in future shortwave radios.)
3) DRM is legal on the shortwave broadcast bands, and DRM can transmit text and images.
4) Text and images via analog radio requires less spectrum (bandwidth) than DRM.
5) Text and images via analog radio are a useful new application for underutilized shortwave transmitters and frequencies.
6) Text and images via analog radio extend the range of a shortwave transmitter, resulting in accurate content in conditions where voice transmissions may be unintelligible.
7) Digital modes via shortwave can be a useful alternative when the Internet is not available due to disasters or to net censorship by dictators.

On the same note, SWLing Post contributor, Harald Kuhl, also comments with a news release from DigiDX:

“DigiDX transmissions via Channel 292 (6070kHz) and suspended until further notice. This is due to action by the German regulator Bundesnetzagentur against digital mode transmissions and is beyond our control. Broadcasts via WRMI will continue and we hope to find another outlet to use for transmissions to Europe.”

[later:]·

“Good news – Thanks to Jeff White we have another frequency for this Sunday’s broadcast which should be better for Europe. 15770kHz at 2130. Please can anyone in Europe, North America and elsewhere please send reception reports to [email protected] for this extra broadcast.”

Sources: DigiDX website & FB

Spread the radio love

VOA Radiogram this weekend

How to decode WBCQ’s digital message

6 Replies

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.

Spread the radio love