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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 -----
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
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