RECEIVING RADIOGRAM SIGNALS ON SHORTWAVE

radiogram signals

Receiving Radiogram signals on Shortwave.

Shortwave Radiogram transmits digital text and images on shortwave using a standard analogue shortwave transmitter. These signals can be received and decoded using a simple AM shortwave radio and either a computer or Android phone using free decoding software.

Currently, Radiogram transmissions are made on:

Shortwave Radiogram Program Schedule
Friday0630-0700 AEST7780 kHz
5950 kHz
MFSK32
MFSK64
50 Kw WRMI Florida
Saturday0200-0230 AEST9400 kHzMFSK32
MFSK64
100Kw Space Line, Bulgaria
Sunday0930-1000 AEST7780 kHzMFSK32
MFSK64
50 Kw WRMI Florida
Monday1800-1830 AEST7730 kHz
5850 kHz
MFSK32
MFSK64
50Kw WRMI Florida

There are several steps required to get ready to receive radiogram signals.

The decoding software for Radiogram transmissions is called FLdigi (other programs can also be used). This can be downloaded from: sourceforge.net/projects/fldigi/files/. Select fldigi.exe and download to your computer. The software was developed by and American amateur radio operator W1HKJ and is free to use. Anroid devices require free decoding software called TIVAR.

Its important not to miss the beginning of a radiogram broadcast. The RSID instruction (it forces FLdigi to the correct decoding mode automatically) is transmitted the begining of the broadcast and also whenever the mode is changed. For this to work correctly the RRXiD button in the top right hand corner of the FLdigi screen must be selected (turns green when activated).

Android Phone:

For those using an Android phone, TIVAR is all that is required. Simply tune to the Radiogram frequency at the appropriate time, start the TIVAR application and place your phone near the receiver speaker. Images and text should be decoded if you can receive the signal.

Computer:

In order to couple the receiver audio into your computer (via the line input socket on the soundcard and the line output or speaker socket on the receiver), you will need to download a free “Virtual Audio Cable”. This is simply an electronic software connection inside the computer to connect the receiver audio to the decoding software.

If using a laptop, simple “acoustic” coupling is all that is required, using laptop microphone.

If your receiver doesn’t have a line output socket, you can still use the speaker output but you wont be able to listen to the radio signal, unless you use a Y cable or adaptor. These are normally sold as a 3.5mm stereo plug to 2 mono RCA sockets or plugs. Electronic parts suppliers such as Jaycar sell such items (cat # WA7014, WA7404, PA3580 and PA3582 are amongst suitable adaptors.

You can down load a virtual audio cable from: https://www.vb-audio.com/Cable/. This software is not freeware and all support contributions by way of donation, are accepted. Simply download the zipped folder to anywhere on your computer and select : VBCABLE_Setup_x64.exe. For older computers (32 bit) select: VBCABLE_Setup.exe

When receiving a Radiogram signal, select “VB Audio Virtual Cable” from your computer speaker selection.

Remote receivers:

If you don’t have a shortwave receiver, or you live where no shortwave reception is possible, its also possible to enjoy receiving radiogram signals via an on line SDR. Simply logon to the SDR ( go to https://sdr.hu/ for a worldwide list), select an SDR located close to the transmission source (either Florida or Bulgaria in this case), select AM mode and the desired frequency. Then select the Virtual Audio Cable in your computer speaker selection) and open FLdigi.

FLdigi has a function that can automatically optimise all parameters for the incoming signal. Just click on RxID in the upper right hand corner of the screen, before the broadcast starts.

You should begin receiving text and images (there is a schedule available at swradiogram.net/) during the 30 minute broadcast duration.

These images were decoded from the Tecsunradios.com.au SDR from a broadcast on June 18, by a listener in the UDSA.
print shortwave radio tecsun 310et
print shortwave radio tecsun 310et