|Subject:||Re: ULF: Ground loop night transmission 3.0|
|From:||Markus Vester <[email protected]>|
|Date:||Mon, 15 Apr 2019 20:02:52 +0000 (UTC)|
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> Do you have an idea why the E-W cardioid result is worse than from the E field alone?
Looking at https://vlf.u01.de/VLFgrabber/vlf9.jpg we find that the noise grew much more on the earth loop (top) than on the E-field (bottom). One reason may be that our earth antennas pick up more 50 Hz harmonics - these won't interfere with your QRG directly but may raise the noise blanker threshold and make spherics blanking less effective. We could also speculate about spherics with steep incidence angle, albeit you were more or less in the middle between 1st and 2nd vertical tweek resonances (1.65 and 3.3 kHz). Anyway the SNR ratio between H to E seems to be similar to your receivers.
Of course skywave components may also have a direct effect on your signal but I don't know whether that would have been positive or negative, or in which way to extrapolate downwards. I'm very curious what would come out of a 1.65 kHz transmission during a quiet night.
> Which carrier S/N do you get from the E field?
Decoder output "carrier S/N 24.31 dB in 128.6 uHz" - should be related to carrier Eb/N0 by adding 10 log (ncharacters * 5.7).
Von: DK7FC <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Mo, 15. Apr. 2019 10:32
Betreff: Re: ULF: Ground loop night transmission 3.0
Hello Markus, ULF,
Very well. Thanks for your decodes and for sharing the night :-)
Do you have an idea why the E-W cardioid result is worse than from the E field alone?
Which carrier S/N do you get from the E field? I'm getting carrier S/N: 40.62 dB in 128.6 uHz, 1.71 dB in 1Hz
The difference of our carrier Eb/N0 is 16.3 dB. But as Paul mentioned, camparing carrier S/N may be more accurate in that spectrum range.
It could be interesting to compare the SNR difference between our locations over some frequencies. If that value is reasonable constant, in the far field, then we could estimate what we can expect at 970 Hz...
My results from all 3 antennas are still looking good at that frequency:
E field: carrier S/N: 40.62 dB in 128.6 uHz
N-S loop: carrier S/N: 28.38 dB in 128.6 uHz
E-W loop: carrier S/N: 30.47 dB in 128.6 uHz
Am 15.04.2019 01:33, schrieb Markus Vester:
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