Hello Jay,
The whistlers seem to have gone asleep temporarily, but yesterday they
returned around European midnight..
There is a short description of the RX setup here:
http://www.qsl.net/dl4yhf/vlf_reception/VLF_Receivers.html
For the VLF stream (sent to Paul Nicholson's stream server), remaining
hum is removed by digital processing. It is actually an automatic
multi-notch filter, which eliminates any signal with more or less
constant frequency. You can see this if you look at the audio spectrum
with a large frequency resolution: There are gaps at multiples of 50 Hz,
up to a few kHz. Since there are no strong whistlers present at the
moment, I will turn off the hum filter for say 2 minutes at 21:00 UTC so
you can hear the difference.
Cheers,
Wolf .
[email protected] schrieb:
Wolf
Listening to your feed now...great whistlers currently. Can you
describe the receiving setup? The absence of hum is impressive.
Jay W1VD WD2XNS WE2XGR/2
----- Original Message ----- From: "Wolfgang Büscher" <[email protected]>
To: <[email protected]>
Sent: Monday, March 22, 2010 2:57 PM
Subject: Re: VLF: Whistlers again
Hi Paul,
Paul wrote:
Short interruption to the downlink here Wolf?
http://abelian.org/vlf/event.php?stream=vlf6&id=1269221358
No I think it is odd, the signal is there but at a
different sample rate? Computer glitch?
Obviously the winamp/oddcast combination had a problem with the
temporary disconnection by the DSL provider. I had to shutdown and
restart winamp/oddcast, then all was ok again. While that happened,
the soundcard (emu 0202) and hum filter etc kept running, which
possibly caused some buffer overruns. I noticed this by accident when
the *sending* computer also began to stutter (there is a "monitor"
audio output in the oddcast plugin, sending the same data to the
stream and to the soundcard). Will leave it running overnight to see
if similar sh** happens again around 02 or 03 UTC ..
At the moment, some really nice whistlers here going down in
frequency below 700 Hz.
Cheers,
Wolf .
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