Hello Markus, VLF, ULF,
Thanks for the todays tests and the good cooperation. Amazing what we
can do meanwhile, watching smaller variations of the signal levels,
which would not be possible from my large INV-L antenna because we
could not get such an SNR in that bandwidth.
These were the transmissions today (+ some more parameters):
T2019-04-05_10:39,+35m: 5170.1 Hz @1130m, I = 2,39 A, P = 461 W, C =
767 nF
T2019-04-05_11:19,+51m: 5170.1 Hz @900m, I = 2,92 A, P = 566 W, C = 867
nF
T2019-04-05_12:14:20,+10m: 970.1 Hz @900m, I= 3.09 A, P = 613 W, C =
10.2 uF
T2019-04-05_12:30,+38m: 970.1 Hz @1130m, I = 2.49 A, P = 500W, C = 7 uF
73, Stefan
Am 05.04.2019 16:36, schrieb Markus Vester:
At DL0AO, we produced spectrograms and plots during the 5.17
kHz test last weekend. During the first session with the shorter
guiderail antenna, signficant fading and a dip occured, most
pronounced on the H-field receive antenna. Another deep dip happened
immediately after Stefan switched to the long antenna, however
that period may perhaps have been affected by a short retuning
interruption at 12:58. Considering around 17 dB SNR in 1.5 x 3.8
mHz, the 6 dB variations seems to be too large to be explained by
random noise alone. Thus we have been speculating about ionospheric
variations or scintillations on a ten-minute timescale. Note
that no solar x-ray or SID event had happened at the time.
Therefore I asked Stefan to repeat the test, which he did today, this
time starting on the long antenna (10:39 - 11:15) and then going
to the short one (11:19 - 12:10). This time the SNR was even better,
and only small variations occured, perfectly within the range of noise
statistics.
Best 73,
Markus (DF6NM)
-----Ursprüngliche Mitteilung-----
Von: DK7FC <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Mi, 3. Apr. 2019 20:26
Betreff: Re: VLF: Ground loop improvements and test carrier...
PS: Earlier that day, the same test was done at 5170.1
Hz. But there,
the antenna current was different:
900m: T2019-03-31_12:31,+19m at I = 2.74 A
1130m: T2019-03-31_12:57,+31m at I = 2.12 A
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