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[Linrad] Re: Quartet Soundcard and Linrad and Windows


Do you think this applies to other drivers as well?  After playing with some SB drivers, windows started behaving this way with Rocky and all sound cards.  

Windows may have a mode where it does this and a mode where it doesn't.  I would like to know how to switch that mode back.

Jeff, wa1hco
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-----Original Message-----
From: w3sz <73w3sz@xxxxxxxxx>

Date: Mon, 26 Jan 2009 23:35:31 
To: linrad@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Subject: [Linrad] Quartet Soundcard and Linrad and Windows

Hi All,

I already relayed this information to Leif, but I think it will be 
useful to the list as well.  This description applies to Windows XP.

I did the experiment of running Linrad03-01 at sampling speeds of
48 kHz, 96 kHz, and 192 kHz with WAVEFORMATEXTENSIBLE set to 'y' or 'n'.

With it set to 'y', both 96 kHz and 192 kHz sampling speeds had the 
useful signal bandwidth reduced to 48 kHz; outside of the central 48 kHz 
of spectrum the signal was reduced to zero.  With it set to 'n', both 
sampling speeds had the useful signal width at full value: 96kHz or 192 
kHz respectively, as selected.

With 48 kHz sampling speed, the full 48 kHz is seen with either 'y' or 

With WAVEFORMATEXTENSIBLE set to 'n' there is no choice between 16 and
24 bits, but only 16 bits is permitted regardless of sampling speed chosen.

So, although one selects 96 or 192 kHz with WAVEFORMATEXTENSIBLE, 
Windows decides to do something else.  It gives the appearance of 
applying a low pass filter limiting signal to +/- 24 kHz of zero, but it 
may really be a resampling effect.  While I knew that cheap 'on board' 
sound was subject to resampling under Windows, I am surprised to find a 
quality sound card treated this way by Windows!

The solution for me is to run with WAVEFORMATEXTENSIBLE = 'n' and thus 
use 16 bits.  Then the sampling is as desired.


Roger Rehr

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