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Date: Sat, 20 Jun 2015 21:04:22 +0200
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Subject: LF: VLF vorbis stream, Question
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Hi all,

There are vorbis streams available on VLF by Paul Nicholson and 
Wolf/DL4YHF and a few more known people from the scene. As far as i know 
these are in vorbis format, like my MF/VLF stream.
What i found yesterday, the data rate depends slightly on the volume level.

Now i'm asking myselfe if there is a 'quality' loss when using a low mic 
volume level ??

To become more precise: The usual method is to check where the noise 
level of the soundcard can be found, e.g. in Speclab it shows -120 dB 
for example. Then, if one connects the RX, it may rise to -118 dB (in 
what ever FFT bin width and Mic gain level). Then, connecting the 
antenna to the RX may let the (daytime!) noise level rise to -100 dB. 
Then one knows that the daytime band noise level is 18 dB above the 
noise level of soundcard+RX and _*everything is fine*_ and the dynamic 
range is somewhere near 100 dB or maybe just 90 dB but at least it is 
high enough...
*Can this method or thinking be applied when SpecLab is getting its data 
via a vorbis stream???*
I can detect the noise level without an antenna connected and prove that 
it is about 20 dB lower as when the antenna is connected. So i assumed 
that everything is all right. But when playing with the mic gain level, 
i can see that the data rate rises about 10% when adding another 20 dB. 
So is there a loss of data, resulting in a lower SNR of incoming signals 
when using a low mic level, although it is still well enough above the 
soundcard+RX noise?? (Of course i want to keep the mic level as low as 
possible without a quality loss, to have a dynamic range as high as 
possible)
I just noticed that effect last night and now i'm aksing if there are 
unwanted losses.

73, Stefan

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Hi all, <br>
<br>
There are vorbis streams available on VLF by Paul Nicholson and
Wolf/DL4YHF and a few more known people from the scene. As far as i
know these are in vorbis format, like my MF/VLF stream.<br>
What i found yesterday, the data rate depends slightly on the volume
level. <br>
<br>
Now i'm asking myselfe if there is a 'quality' loss when using a low
mic volume level ??<br>
<br>
To become more precise: The usual method is to check where the noise
level of the soundcard can be found, e.g. in Speclab it shows -120 dB
for example. Then, if one connects the RX, it may rise to -118 dB (in
what ever FFT bin width and Mic gain level). Then, connecting the
antenna to the RX may let the (daytime!) noise level rise to -100 dB.
Then one knows that the daytime band noise level is 18 dB above the
noise level of soundcard+RX and <u><b>everything is fine</b></u> and
the dynamic range is somewhere near 100 dB or maybe just 90 dB but at
least it is high enough...<br>
<b>Can this method or thinking be applied when SpecLab is getting its
data via a vorbis stream???</b><br>
I can detect the noise level without an antenna connected and prove
that it is about 20 dB lower as when the antenna is connected. So i
assumed that everything is all right. But when playing with the mic
gain level, i can see that the data rate rises about 10% when adding
another 20 dB. So is there a loss of data, resulting in a lower SNR of
incoming signals when using a low mic level, although it is still well
enough above the soundcard+RX noise?? (Of course i want to keep the mic
level as low as possible without a quality loss, to have a dynamic
range as high as possible)<br>
I just noticed that effect last night and now i'm aksing if there are
unwanted losses.<br>
<br>
73, Stefan<br>
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