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RE: [Discuss-gnuradio] Parallel Port Interface

From: Joseph DiVerdi
Subject: RE: [Discuss-gnuradio] Parallel Port Interface
Date: Mon, 20 Jan 2003 15:15:03 -0700

Dear Matt,

At 2:03 PM -0800 1/20/2003, Ettus, Matt wrote:
>> Do 96ksample/s cards have 48kHz of actual bandwidth or will 
>> some analog filters need to be disabled?
>They're pretty close.  I've seen 44 to 46 kHz quoted.  Leif Asbrink gets 90+
>kHz total.  Some cards might have narrower filters in front, but the
>majority don't.
>> How wide of a hole surrounding 48kHz will this scheme have?
>Most sound cards go down to about 10 or 20 Hz, so you would have a 20 to 40
>Hz hole.  You might be able to remove the DC block, but it isn't worth the
>> Can the sampling clock for a sound card be derived externally?
>On some of them.  Why do you need that?

Part of the project is the measurement of the phase of the incoming signal and 
an absolute reference (relatively speaking) is required. This clock will be 
derived from measurements of WWV's 10MHz carrier.

>> Your scheme gives me another idea to use the sound card: use 
>> a pair of track/hold devices to sample the raw analog 
>> voltages, one at a time, at 192kHz and offer these 
>> alternating time points to the two channels of the sound card 
>> at 96kHz, generating the timing externally as I already have 
>> as a requirement.
>I don't see the point of this, and I doubt it would perform better.

It wouldn't perform any worse. :) It wouldn't have a hole at 48kHz and there 
might be other benefits.


Best regards,
Joseph A. DiVerdi, Ph.D., M.B.A.          
http://diverditech.com/           970.980.5868 (voice) 
http://xtrsystems.com/            970.224.3723 (fax)
PGP Key ID: 0xD50A9E33

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