[AG-TECH] Transmission feeback

Mike Daw mike.daw at man.ac.uk
Fri May 25 10:47:43 CDT 2001

Dear all,

I was wondering what part of the Access Grid coped with "mix minus one"
audio, because, apparently, the AP400 does not do this. Without it (I am
told), there is a problem with "transmission feedback" (i.e. awful howl!)
when there are more than 2 sites communicating. I guess this can't be a
problem with so many sites up and running, so how is it done?

This question was asked by our suppliers of the AP400. (In case you were
wondering how such an obvious novice came to be asking such a technical
question when our kit has not even arrived...!)

This supplier has literally just emailed me and added:
"We have had problems dialling older American 'mulitpoint Bridges" as in
America the technology has been around longer and in the old days the
endpoint had the "mix Minus 1". In England our systems assume the Multipoint
bridge has the "Mix minus 1". This means if you try to "multipoint" several
English endpoints without this facility in your "node" you will get "all
manner of problems". "!"

Any comments...?

Mike Daw
Computer Services for Academic Research (CSAR)
Manchester Computing, University of Manchester
Manchester M13 9PL, UK
Tel: +44 (0)161 275 7026 Fax: +44 (0)161 275 6800
Email: mike.daw at man.ac.uk

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