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

David E. Bernholdt bernhold at jumby.csm.ornl.gov
Fri Aug 10 17:03:03 CDT 2001

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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