From: Praveen Kumar (pkk7_at_y...)
Date: 2001-05-14 17:44:33
Hi everyone,
I checked the group mail after a while a was
pleasantly surprised to see
that discussion on sound card has gained momentum. I
wish to set aside the
apprehension of Eric regrading the quality. Quality
will not be
compromised as its the proven hardware. Rest will be
determined by
software. Rob Sacks and Jiva have given good links
which can help in
development of software. I'm going to look at it as I
send this message.
Most of the discussion is centred around the low pas
cutoff frequency.
First we should freeze what freq are we looking for.
There are two possible
solutions:
1. As suggested by a member earlier, Changing the
input capacitor.
(or)
2. Amplified input analog signal can modulate a VCO
which are cheap and
readily available. I've designed my own for my work
and can be made
available to the group. Due to high sampling frequency
of the sound card,
the modulated signal can be easily acquired. Another
advantage of this
method is the signal can traverse long distance if
the patient is much away
from PC. However, the domdulation will have to be
done by PC based software
(don't know how to do it). The frequency response
down to DC (or anyother
low cutoff freq) is possible with this method.
Let us focus on the some more (if any) grey areas
before we commit ourselves
in the implementation.
Cheer,
Praveen
India
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This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:29 BST