[AG-TECH] New install -- planning for mics

Terry Disz disz at mcs.anl.gov
Fri Aug 10 17:20:08 CDT 2001


The number of mic's is not a big deal, the requirement is that you use as
many mics as you need to be able to hear people in the room clearly. In most
cases that is more than two mics. I understand that the pzm mic should be
able to do a good job in a room of the size that you are talking about, but
we haven't ever had that kind of luck. Ours have always picked up too much
background noise - in fact we can't use them in any of our rooms.

I suggest you just try it and see, and be prepared to add a few more if

I think you can switch the mic from the gentner to the polycom when the
gentner is not in use, but to switch it when the gentner is working would
confuse it. Your understanding is correct.



-----Original Message-----
From: owner-ag-tech at mcs.anl.gov [mailto:owner-ag-tech at mcs.anl.gov]On
Behalf Of David E. Bernholdt
Sent: Friday, August 10, 2001 5:03 PM
To: ag-tech at mcs.anl.gov
Cc: bernholdtde at ornl.gov
Subject: [AG-TECH] New install -- planning for mics

We're about to install an AG node and some Polycom H.323 equipment in
the same room.  Looking at another room on site with the Polycom
equipment, I noticed that they were using only two microphones in a
large room, probably at least 20' x 30'.

They had the Polycom-supplied mic on the front wall, immediately below
the screen and a PZM mic on the ceiling just behind the projector.
The PZM was installed in a plexiglass shield, which keeps it from
picking up projector noise, and presumably helps funnel sound from the
rest of the room a little.

They say that get excellent results from this setup.  In fact,
collaborators are apparently able to hear side conversations carried
out near the back of the room!

So I wonder as to the motivation behind using so many mics in AG (the
hardware spec says that every speaker should be within 2-5' of a mic),
and whether anyone has tried in AG a setup like I described?

Also, the spec says that all mics have to be plugged directly into the
Gentner.  I can understand not mixing mics in different physical
locations into a single input because that could screw up the echo
cancellation algorithm.  But does that mean I can't even put a simple
switch in the line, which would allow me to share a mic between the AG
and the Polycom?  If this is a problem too, can someone please explain

Thanks, David
David E. Bernholdt                   |   Email: bernholdtde at ornl.gov
Oak Ridge National Laboratory        |   Phone: +1 (865) 574 3147
http://www.csm.ornl.gov/~bernhold/   |   Fax:   +1 (865) 574 0680

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