Message-ID: <4BA7D7F3.2060802@freenet.de>
Date: Mon, 22 Mar 2010 21:49:55 +0100
From: =?ISO-8859-15?Q?Wolfgang_B=FCscher?= <dl4yhf@freenet.de>
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To: rsgb_lf_group@blacksheep.org
References: <4BA7B009.7010406@freenet.de> <4BA7B98C.2080104@abelian.org> <4BA7BD7D.3060504@freenet.de> <000401cac9f8$665bb900$6c01a8c0@DELL4>
In-Reply-To: <000401cac9f8$665bb900$6c01a8c0@DELL4>
Subject: Re: VLF: Whistlers again
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Hello Jay,

The whistlers seem to have gone asleep temporarily, but yesterday they=20
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=20
hum is removed by digital processing. It is actually an automatic=20
multi-notch filter, which eliminates any signal with more or less=20
constant frequency. You can see this if you look at the audio spectrum=20
with a large frequency resolution: There are gaps at multiples of 50 Hz,=
=20
up to a few kHz. Since there are no strong whistlers present at the=20
moment, I will turn off the hum filter for say 2 minutes at 21:00 UTC so=
=20
you can hear the difference.

Cheers,
  Wolf .

jrusgrove@comcast.net schrieb:
> Wolf
>
> Listening to your feed now...great whistlers currently. Can you=20
> describe the receiving setup? The absence of hum is impressive.
>
> Jay W1VD  WD2XNS  WE2XGR/2
>
>
> ----- Original Message ----- From: "Wolfgang B=FCscher" <dl4yhf@freenet.=
de>
> To: <rsgb_lf_group@blacksheep.org>
> 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=3Dvlf6&id=3D1269221358
>>>
>>> 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=20
>> temporary disconnection by the DSL provider. I had to shutdown and=20
>> restart winamp/oddcast, then all was ok again. While that happened,=20
>> the soundcard (emu 0202) and hum filter etc kept running, which=20
>> possibly caused some buffer overruns. I noticed this by accident when=
=20
>> the *sending* computer also began to stutter (there is a "monitor"=20
>> audio output in the oddcast plugin, sending the same data to the=20
>> stream and to the soundcard). Will leave it running overnight to see=20
>> if similar sh** happens again around 02 or 03 UTC ..
>>
>> At the moment, some really nice whistlers here going down in=20
>> frequency below 700 Hz.
>>
>> Cheers,
>>  Wolf .
>>
>>
>
>
>
>