DK8KW Longwave Information
I recorded the background noise at my QTH for
24 hours to see what the best window for a sked might be. I wake up early
anyhow, so 04.00 UTC is the best time, but also the time up to 10.00
UTC is fine. After that time, the noise level is too high. I have no idea
what causes that high noise, but especially the sharp noise decrease just
before 04.00 UTC is a clear evidence for man-made noise.
I used a simple multimeter with RS-232 output (Voltcraft/METEX M-3850)
and measured the s-meter level output of my MV61
(0-2 Volt). One datapoint every 2 1/2 minutes was recorded, which results
in about 600 datapoints over 24 hours. The data where then imported into
Excel and the voltage (0 to 2 Volt) converted into dBu
(75). The frequency 137.400 kHz was selected, because this is a frequency
that is relatively free, bandwidth was 100 Hz.
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