DRM Test to Japan

DRM Test to Japan

On May 24, 25 2013 KTWR did a test DRM broadcast to Japan. Our previous DRM test to India had brought more reception reports from Japan than India. With that much interest we decided to contact a colleague in Japan and have a test block produced in Japanese and see how we could do, with a full stereo broadcast focused directly to Japan.

This was one of the most successful test broadcasts we have had to date. We have currently received 30 reports for this test block. One reason this is most remarkable, is because of some unique broadcast conditions.

Just prior to going on the air, at the test date, we received word that there was a clandestine broadcaster and a jammer using this frequency and spectrum around it. This gave us the worst analog conditions we could ask for. As a result, we didn’t get the coverage area we anticipated.

Mostly in consideration of our target area, Japan, we were encouraged that a number of the reports indicated excellent reception. Fortunately, our signal was well received and robust in many locations , mostly south of Tokyo, but also a listener in the far north wrote in with a very enthusiastic response of how enjoyable the stereo broadcast was.

Some comments from listeners about the content of the test transmission: “Inspiring”/”nostalgic”/”great in stereo sound”/”good”/”fun”

There were also comments about the interference of the strong analog signal that did cause program loss, as noted in a number of reports. Screen shots showed the interference from the analog broadcasters bleeding into our test block. When I think of how an analog transmission on this frequency would have been un-listenable with extremely unpleasant noise, it was encouraging to hear soundbytes of the broadcast this clear and robust. There was even a sound file from Ulaanbaatar, Mongolia that was clear and robust.

We broadcast in robustness mode B, 64 QAM , audio mode – param. stereo.

Conclusive results from a technical standpoint:

1) We can provide a clear powerful stereo broadcast to Japan.

2) The capability of DRM to deal with the worst conditions is remarkably good.

Because of the very encouraging response to this test, it has prompted us to consider we need to provide another test to show what this sounds like on a non-interference frequency! We will be doing another test on 14 and 15 June at 1230-1300 UTC on 12040 kHz.

Stay Tuned.

George Ross
KTWR, Guam
Listen to two sound files recorded in Kobe Japan and Ulaanbaatar Mongolia of the test broadcast.


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