Telex Azedit, Software Manual

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Telex Communications 105
Inter-panel Dim Tables
An Inter-panel Dim Table is simply a list of two or more keypanels that are located in close proximity to one another.
Dim is placed on the talk key as a second level function. When entered, the Dim invokes the processor to search all
the dim tables whenever the talk key is pressed. In this situation, if the keypanels are using a speaker/microphone
combination, feedback could occur if two keypanels have keys activated to communicate with the same destination,
or if one keypanel has a key activated to talk to the destination and the other is receiving audio from the destination.
By using an inter-panel dim table, the intercom system automatically mutes, or dims, one or both keypanel speaker
outputs while this situation exists. When you configure a dim table, you can also define the amount of speaker
dimming. For example, suppose you and I are seated near each other in a VTR room (video tape recorder room in a
broadcast studio). We each have a talk key assigned to talk to the director. Suppose I am currently listening to the
director (either the director is talking to me, or I have a listen key activated). At this moment, you press your talk key
to the director, and feedback is immediately noted in the keypanel speakers. This is because your audio enters your
mic, then comes out the director's speaker, then re-enters the director's mic, then comes out my speaker, then re-
enters your mic to create a continuous feedback loop.
To eliminate the feedback, we set up a DIM table with you and I as members, and we set the dim value to -9dB. We
then assign the DIM function on Talk Level 2 of our keys that talk to the director. Now suppose the director is talking
to me, and your talk key to the director is off. I will hear the director at the normal level. However, when you press
your talk key to the director, you activate the DIM function (via the talk level 2 assignment on your talk key). The
master controller searches for any DIM tables in which you are a member, then dims the volume from the director to
all other members of the same DIM table by the dim amount specified in that DIM table. In this case, there is only one
DIM table, with you and I as members, and with a dim amount of -9dB. So, when you press your talk key, the volume
from the director to me is dimmed by 9dB, which should hopefully reduce or eliminate the feedback. If I were to then
press my talk key to the director, the volume from the director to you would also be dimmed by 9dB.
Suppose there are three of us in the VTR room (Ralph is on your right and I am on your left). We all have talk keys
assigned to the director. Suppose that there is a feedback problem between you and I, and between you and Ralph,
but Ralph and I can talk and listen to the director without feedback occurring. In this instance we create two DIM
tables, one with you and I as members, and one with you and Ralph as members. When you then press your talk key
to the director, both of the DIM tables with you as member become active. If I am listening to the director, the listen
volume from the director to me is dimmed by the amount specified in the DIM table where you and I are members. If
Ralph is also listening to the director, the volume from the director to Ralph is dimmed by the amount specified in the
DIM table where you and Ralph are members.
If there were a feedback problem between Ralph and me, we could use one DIM table with all three of us as
members (with only one dim amount). Or, we could use a third DIM table with Ralph and me as members (say with
only -6db dimming since we sit further apart).