Tag Archives: Digital Modes

WRMI to showcase digital modes via analog radio

31-meter-Spectrum (Source: VOA Radiogram via Richard Langley)

WRMI, Radio Miami International, will showcase digital text and images via analog radio in a half-hour special broadcast to be transmitted nine times (at least), beginning Saturday, 13 August.

The broadcast will mostly be in MFSK32 centered on 1500 Hz. There will also be segments in MFSK64, MFSK32 centered on 2200 Hz, and Olivia 64-2000. The program will include MFSK images, examples of non-Latin alphabets, and an Flmsg transmission. You will also hear “co-channel” music.

To decode the modes on the WRMI broadcast, Fldigi software is recommended. Download it fromhttps://sourceforge.net/projects/fldigi/files/fldigi/ . The main Fldigi website is http://www.w1hkj.com.

And you will use the companion program Flmsg. Download it fromhttps://sourceforge.net/projects/fldigi/files/flmsg/ .

To make Flmsg work with Fldigi, in Fldigi: Configure > Misc > NBEMS > under Reception of flmsg files, select Open with flmsg and Open in browser, and below that indicate where your Flmsg.exe file is located – probably somewhere in Program Files(x86).

For correct decoding of the languages with diacritics, or using non-Latin alphabets, in Fldigi: Configure > Colors & Fonts > RxTx > in the Rx/Tx Character set menu, select UTF-8.

For Fldigi to automatically select the mode and the center audio frequency of the mode, select RxID (upper right of the interface) by left clicking. In newer versions of Fldigi, also right click on RxID and select Passband.

You can decode this WRMI special broadcast as it is broadcast, or from your recording.

TRANSMISSION SCHEDULE

Via WRMI’s transmitters at Okeechobee, Florida, except where noted:

Saturday 13 August 0030-0100 UTC on 7730 kHz (285 degrees azimuth)
Saturday 13 August 0730-0800 UTC on 5850 kHz (315 degrees)
Saturday 13 August 1330-1400 UTC on 11580 kHz (44 degrees)
Saturday 13 August 2200-2230 UTC on 5950 kHz (181 degrees)
Sunday 14 August 0230-0300 UTC on 11580 kHz (44 degrees)
Sunday 14 August 2130-2200 UTC on 15770 kHz (44 degrees)*
Sunday 14 August 2330-2330 UTC on 11580 kHz (44 degrees)*
Monday 15 August 2000-2030 UTC on 6070 kHz* **
Tuesday 16 August 2130-2200 UTC on 15770 kHz (44 degrees)

* Preempts DigiDX, usually heard at this time

** Via Channel 292, Germany

Many of these broadcasts will be heard outside their nominal target areas.

Reception reports to Jeff: info (at) wrmi.net

There’s a pattern in that noise!

Digital-Image-VOA-Radiogram

Many thanks to SWLing Post contributor, @K7al_L3afta, who just shared the image (above) and noted, on Twitter:

“I just discovered the noise at the start of [the VOA Radiogram has] a purpose!” 

That’s a brilliant discovery!

Click here to learn about the VOA Radiogram.

Click here to follow @K7al_L3afta on Twitter.

Update: German communications regulator to allow AM digital modes

FLdigi-VOARadiogram

As a follow-up to a previous post, many thanks to several SWLing Post readers who noted this news on the VOA Radiogram website:

The German communications regulator Bundesnetzagentur has changed its mind about allowing digital modes on shortwave broadcast transmitters in Germany. Apparently BNetzA thought that Channel 292 was transmitting the text and images in single sideband (SSB), which is how amateurs, military, etc, transmit the digital modes. Now that they know that the MFSK32 and other modes are sent as program audio on an analogue amplitude-modulation shortwave transmitter, their objections were withdrawn.  (It’s similar to A2A modulated CW.)

BNetzA prefers that the term MFSK32 not be used to describe these broadcasts, but we have to specify the mode so that you can set Fldigi or other decoding software to the correct mode. In any case, the weekly MFSK32 transmission will resume on The Mighty KBC, and DigiDX will return to Channel 292.

Meanwhile, VOA Radiogram this weekend will be all MFSK32 except for the transmission schedule in Olivia 64-2000 under the closing music.                       

German regulators prohibit digital modes on broadcast bands

DigiDX

(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 reports@digidx.uk for this extra broadcast.”

Sources: DigiDX website & FB

How to decode maritime broadcasts in RTTY, Sitor B, and NAVTEX

(Photo Credit: NOAA)

(Photo Credit: NOAA)

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN) for the following guest post:


Maritime Broadcasts in RTTY, Sitor B, and NAVTEX.

By Mario Filippi, N2HUN

(All photos below are courtesy of the author. Click each image to enlarge.)

Non-voice high seas weather broadcasts and safety messages to mariners can be found by spinning your VFO dial to 8.472 MHz USB courtesy of WLO from Mobile, AL, which provides these transmissions continuously. Here on the East Coast it is received with regularity due to it’s strong signal.

Those of you who are neophytes to RTTY or just want to dabble then this is the place to be to try your hand at an old and venerable digital mode. The RTTY (RadioTeleTYpe) parameters used by WLO transmissions are 45.45 bauds, 170Hz shift. These are most commonly used by amateur radio ops too. If you’ve roamed the bands for RTTY signals you’ll find that most are encrypted with a few exceptions, one of which is WLO which is transmitting continuously.

Tabletop SW radio set to WLO; SignaLink USB links radio to computer for decoding.

Tabletop SW radio set to WLO; SignaLink USB links radio to computer for decoding.

On 8.472 MHz you’ll receive weather information from different latitude/longitudes, along with other pertinent information to mariners such as high seas pirates (not radio pirates!) and naval maneuver areas that are important for ships to avoid. It makes for interesting copy.

To decode RTTY signals you’ll need a shortwave receiver with a BFO (Beat Frequency Oscillator), a way to pipe your radio’s audio into your computer’s sound card, and decoding software. There are several RTTY software packages out there, free, and my favorite is MMTTY. More info on MMTTY is at: http://hamsoft.ca/pages/mmtty.php . Old timers will find this software a snap to use, but newcomers will have to fiddle with the controls to get the decoding going. Below is a snapshot of MMTTY decoding a typical weather broadcast.

MMTTY dashboard with WX info. Cross-like indicator on upper right aids in tuning signal.

MMTTY dashboard with WX info. Cross-like indicator on upper right aids in tuning signal.

Another software available for decoding RTTY is Fldigi. Again, you’ll have to input the correct RTTY parameters such as baud rate and shift into the program along with adjusting your VFO carefully. It takes practice, but when the decoding is successful you’ll see Fldigi doing it’s thing as shown below. Both MMTTY and Fldigi have waterfalls displaying a visual image of the received signal. With practice you’ll be able to distinguish the different common RTTY shifts just by looking at the waterfall.

Fldigi in action with split screen; RTTY text above, waterfall below.

Fldigi in action with split screen; RTTY text above, waterfall below.

Now to Sitor B (Simplex Teletype Over Radio Mode B), another non-voice mode we can use to decode WLO transmissions. Sitor B sounds a lot like RTTY to the human ear, but requires different decoding software. WLO transmits weather information via Sitor B immediately after RTTY transmissions, switching back and forth, which makes for even more fun! Software that decodes Sitor B is available on the ‘Net as free downloads. One is MultiPSK, the other is YaND.

I like YaND (Yet another Navtex Decoder) which is used to decode NAVTEX (Navigational Telex) transmissions commonly found on 490 KHz and 518 KHz, but it works well for decoding Sitor B. There is a difference in the way messages are processed in NAVTEX versus Sitor B and for further information perform a Google search. But the fastest and easiest way to decode Sitor B transmissions from WLO is to fire up YaND. Below is a recent NAVTEX HF broadcast capture.

WLO HF WX broadcast for NE Gulf on 1/18/16 .

WLO HF WX broadcast for NE Gulf on 1/18/16 .

Well, hopefully some of you will be inspired to check out maritime weather/safety information found on WLO using RTTY/Sitor B/NAVTEX software. However, RTTY can also be found on the ham bands and on shortwave frequencies. Several RTTY stations from Germany are found on frequencies such as 11.039MHz and 14.467MHz. Their weather information format is quite different and will give you an idea of European weather conditions and allow you to practice your German. When not sending weather info they run a RTTY message loop below at 50bauds/425Hz shift.

German RTTY station with message loop. Deciphered via MultiPSK.

German RTTY station with message loop. Deciphered via MultiPSK.

In closing, make sure to also check out the NAVTEX broadcasts found just below the AM broadcast band on 490 and 518 KHz; using YaND or MultiPSK you’ll be able to receive these transmissions, but remember you’re not on HF, you are on MW (medium wave), where signal distances are shorter and present a greater reception challenge. YaND software has a NAVTEX broadcast schedule built in as seen below; you have to identify your specific NAVAREA or navigational area, then look at the times and frequencies to determine when to listen in. My QTH is in NAVAREA 4. Lots of interesting information is passed in these NAVTEX transmissions so listen in and have fun!

YaND NAVTEX schedule for various NAVAREAS.

YaND NAVTEX schedule for various NAVAREAS.

NAVTEX on 518 KHz from station VAR-9, New Brunswick, CAN. Messages begin with “ZCZC.”

NAVTEX on 518 KHz from station VAR-9, New Brunswick, CAN. Messages begin with “ZCZC.

Mario Filippi (N2HUN), is the author of this post and a regular contributor to the SWLing Post. Click here to read Mario’s guest posts.