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Old 14-05-2014, 10:12   #1
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Join Date: Dec 2012
Location: Beauvais France JN19BL
Posts: 631
Starting process of DRM TX

I suppose it is automated.
Could it give us information on the type of equipment ?
For example REE on 15585Khz first radiates a carrier with 2 side bands that
I believe are in quadrature as I don't hear them in AM mode
I'll try to wath more care fully and edit this post.
PS Today's starting process looked different and quicker
So maybe it is not automated.
Propagation was worse too.
And shame on me I forgot to record the process

Last edited by F1BJB : 15-05-2014 at 10:02.
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Old 17-05-2014, 10:03   #2
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Join Date: Aug 2012
Location: New Zealand
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Most would be automated and use commercial DRM modulators. RNZI is automated including frequency changes, the building is normally visited every 3 months only for checks. I havent been there but work with the techs who do that site, its about 200 km from the cities and studios, just sheep around the fields they surely stay warm at night. I think the AM service is on the other transmitter so the DRM is probably not changing modulations during the day, just the frequencies and antennas are swapping over on schedule.

You might be hearing a tuning carrier for before DRM transmission starts, some systems need to radiate a low power test tone to trim the transmitter circuits.
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Old 17-05-2014, 17:02   #3
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Thanks for the info.
SW transmitters seems to be quite special because of their frequent
frequency and aerial change.
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Old 18-05-2014, 11:37   #4
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Location: Stockholm - Sweden
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I know that my good old friend xfielder (R.I.P) used an Excel sheet with a special macro that controlled the SW transmitters of Radio Sweden. Hence it changed frequency and also curtain anenna. They had no control of the incoming audio, from Stockholm. That's why the program could end abruptly, because they had to change frequency or/and rotate a log periodic antenna, which took some time.
73's Per - SM0ITS
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