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Date: Sat, 08 Jul 2017 14:31:46 +0200
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: LF: Octo-soundcard for the Raspi, another question
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Status: RO

...another test on all 6 inputs. I generated 3 wav files of each channel 
pair and played them in SpecLab. BTW the signal generator is my DDS VFO 
that i used in the first VLF kite experiments.
http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/ch1...6.png
Looks like CH2 and CH6 are the best ones, at least here. CH3 and CH4 is 
quite the same.
Paul, if you can't find the reason (e.g. an error on my side), i.e. if 
the effect is genuine and hardware based, i would simply tend to use CH2 
and CH6 for the input signal and CH4 for PPS. Eventually i decide to 
build a 3 channel RX for 2x H +1x E and use CH3 as the 3rd input.
Curious about the analysis results...

73, Stefan

Am 08.07.2017 12:58, schrieb DK7FC:
> Hi Paul,
>
> Meanwhile i did more tests:
>
> Used two audio isolation transformers to DC-separate the inputs: No 
> difference.
>
> Am 07.07.2017 20:02, schrieb Paul Nicholson:
>> Can you send or put on the web a short .vt file of ch1 and ch2,
>> (after vttime, vtresample) long enough to contain at least one
>> or two good glitches?
> http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/record.tar
> A fresh 2 channel file, with a tone at 1 kHz on both channels. I also 
> added the log files.
> (some day i will have my own Raspi-based webserver, but there are 
> still to many open projects already).
>
> It looks like the effect is even more expressed at 1 kHz relative to 
> 500 Hz.
>
> In the attachment you can see how it looks in SpecLab.
> First the attachment size was 294 kB. The mail didn't arrive on the 
> reflector. Now it is resized to 238 kB. Let's see if it comes through 
> now :-)
>
> 73, Stefan