Friday, March 22, 2013

Digital Radiograms Gaining Popularity With Shortwave Broadcasters

Taking the lead of the amateur radio community, shortwave stations, WRMI in Miami, Florida; KBC; and VOA with their "VOA Radiogram", and PCJ Radio, are discovering the powerful and robust communications that can be accomplished with modes like Olivia, MFSK64, RTTY, and PSK.

Had we looked back down the road even a decade ago, there is no way anyone would have guessed that shortwave stations would even give amateur radio digital modes a first glance, much less start using digital modes.

Jan Oosterveen of KBC says: "Olivia is a robust digital text mode. It can overcome all types of noise. But can Olivia 8-1000, reduced by 24 dB, be decoded under the amazing voice of country singer Suzy Bogguss? We will find out 24 March 2013 at about 0130 UTC, with the mode centered on 2500 Hz. This will be during The Mighty KBC broadcast to North America, 0000-0200 UTC on 7375 kHz. And at just before 0200 UTC, MT63-1000 (long interleave) in Flmsg format will be centered on 1500 Hz, and an MFSK32 image centered on 2500 Hz." Jan says "Listen between 00.00-02.UTC on 7.375 kHz beamed to North America."

The following joint press release from VOA and WRMI has this useful information:

While it will be strictly one mode at a time this weekend on VOA Radiogram, WRMI, Radio Miami International, will fill its channel (9955 kHz) with multiple instances of digital text.
On Saturday, 23 March 2013, 0400 UTC to 0400 UTC Sunday (midnight to midnight EDT), WRMI IDs will be in BPSK63F, centered on 900, 1300, 1700, 2100, 2500, and 2900 Hertz. (The RSID will guide you to 2500 Hz.)

On Sunday 0400 to Monday 0400 UTC, PSKR250 will be centered on 900, 1700, 2500 (RSID will be 2500 Hz), and PSKR125 on 1300, 2100, and 2900 Hz

The WRMI IDs are generally at the top of the hour and sometimes also at 30 minutes past the hour. Don ‘t let low signal level and noise on the channel discourage you from trying to decode these.
Taiwan-based PCJ Radio International will transmit a message in MFSK32 via WRMI at 0227 UTC on 31 March 2013. 

(End press release) 

Now, since DRM turned out to be dead in the water; this should become interesting since the equipment and software to decode digital modes is easily available, or CAN be accessed by most people even if they have to ask a friend or family member to do it, the wider audience will definitely take interest for the reason that those regions of the globe who have been victimized by China's malicious interference would still be able to decode quite easily since the job of separating interference from digital communications is actually easier than separating it from the spoken voice.

This could very well go beyond an experimental stage to become a trend if stations turn out to like this sort of efficiency. The only real drawback is that digital modes are full duty cycle that can add to wear and tear on transmitters. However, there is a chance that the digital traffic might be pre-recorded, therefore saving the transmitters from the dreadful effects of full duty cycle work.
Here's an interesting thought as this article closes: It would be neat to find out later on down the road that China's choice to use digital modes for malicious interference was the impetus for this trend of experimentation! The next thought to go with it is that it would be interesting if entire programs start to be conducted in digital modes.