Date: Sun, 28 Feb 2010 21:53:05 +0000 (GMT)
From: "Alexander S. Yurkov" <fitec@omskcity.com>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <CDD8913BA26C4C4BAA031227912ECF60@Black>
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Subject: Re: LF: Re: 9kHz noise level
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MNI TNX Markus.

Thus noise level on 9 kHz can be expected abt 1.3*SQRT(1/0.063) = 5.2 uV/m
in 1 Hz by this data. Essentually less then Jim mesured. Thus Stefans sigs
with 20 kV on kite ANT should be detectable at 100 km (2.5 uV/m) at least
in qrss90. Another way of calculation yelds the samilar result: Stefan's power
expected abt 1 mW. 1000 times more then your 1 uW. Then distance should be
SQRT(1000)=30 times more. 6km * 30 = 180 km. Certanly at 100 km there
should be some influence of ionosphere. But seems it is not very strong
yet. Besides good fact is that ionosphere should increase sigs not
decrease. It is pity Stefan can not radiate today. But let's look forward.



On Sun, 28 Feb 2010, Markus Vester wrote:

> Date: Sun, 28 Feb 2010 14:06:35 +0100
> From: Markus Vester <markusvester@aol.com>
> Reply-To: rsgb_lf_group@blacksheep.org
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: LF: Re: 9kHz noise level
> 
> Dear Alexander, LF,
> 
> the frequency rulers of the modified Argo are actually correct, and you can see how I reduced the bandwidth when going further away. The minimum setting was 90 second dots, giving 0.042 Hz FFT resolution when running at 4x normal samplerate (ie. 0.063 Hz noise BW) .
> 
> The marginal "T" trace at 6 km was probably no more than 0 dB SNR. Thus the noise level (including spherics) would have been on the order of 15 dBuV/m/sqrtHz.
> 
> Best 73,
> Markus, DF6NM
>   ----- Original Message ----- 
>   From: Alexander S. Yurkov 
>   To: rsgb_lf_group@blacksheep.org 
>   Sent: Sunday, February 28, 2010 6:33 PM
>   Subject: Re: LF: Re: 9kHz noise level
> 
> 
>   On Sat, 27 Feb 2010, Markus Vester wrote:
>   > In April 2003, I attempted to transmitt an 8.97 kHz carrier, radiating 
>   > about 1 microwatt from my normal LF antenna (220 pF at ~ 9m eff.
>   > height). I drove around and stopped in different places, putting up a 6m
>   > fishing pole with a wire, connected to a resonant circuit and the laptop
>   > soundcard. Each time I took a short Spectrogram full-band screenshot,
>   > along with a narrowband capture from a special Argo version, patched for
>   > 22 kHz samplerate. An assembly of the screenshots is at
>   > http://freenet-homepage.de/df6nm/8970_ALL.gif. Maximum detection range
>   > was 6 km, just marginally outside the reactive nearfield. No
>   > noiseblanking was attempted at the time.
> 
>   Dear Markus,
>   In what qrss mode (FFT-bandwith) you resived such a signal? P=1uW D=6km
>   yelds E=1.3uV/m It seems to be usefull to estimate noise level. But we
>   should normalyze this to bandwith.
> 
>   Regards,
>   Alexander/RA9MB
> 
> 
> 
> 


Regards,
Alexander