Polycom EF2241 - Manual (Page 19)

I
NTEGRATING THE
EF2241 I
NTO
Y
OUR
S
YSTEM
© Polycom, Inc. 17 V ORTEX EF2241 Reference Manual
Customize
Setting for Your
Particular
Application
The following sections will describe customizing parameters on the EF2241 for your
particular application if you are not using Preset 0.
S
ET UP THE
P
HONE
I
NTERFACE
The echo canceller reference of the EF2241 is by default set up with the phone input
already assigned to it.
By default the phone interface will be disabled until you select a country code for the
telephony interface. This can either be done with the front panel LCD menu, or the
RS-232 interface. The country code only needs to be selected the first time or when
the country of the installation is changed.
Send audio from the phone to the outputs on the same device by unmuting the cross-
point of Input T on that output. Send audio from the phone to other linked devices by
using the P bus output in the EF Bus. The linked devices can take the phone signal
off the bus from the P Bus input.
B
UILD
Y
OUR
E
CHO
C
ANCELLER
R
EFERENCE
The acoustic echo canceller (AEC) reference should generally contain exactly the
same audio signals as what is coming out of your loudspeaker(s), since the signal out-
put from the loudspeaker is what is then picked up by the room’s microphones caus-
ing acoustic echo. Note that this statement is a general statement. Conditions for this
being true follow:
If your system
does NOT have
sound
reinforcement,
• The AEC reference should contain exactly the same audio as the loudspeaker
output: all far end audio, audio from the phone add, program audio, etc.
• If your system contains stereo inputs and outputs, the reference must contain a
mix of both stereo inputs. For example, if your VCR audio is in stereo, the refer-
ence should contain both the left and right signals each attenuated by 3 dB, as
well as any other audio that is going to your loudspeaker.
• If you are using crosspoint gains in the loudspeaker mix, apply the same gains to
the signals in your reference.
If your system
has sound
reinforcement,
• Do NOT mix your room microphones into the reference, but include all other
audio (program audio, remote audio, phone audio, etc.).
E
CHO
C
ANCELLER
R
EFERENCE FOR
M
ULTIPLE
V
ORTEX
D
EVICES
In a system with multiple devices, we recommend that one device be designated as
the unit that provides the EF bus reference for the acoustic echo cancellers. This unit
takes one of its reference signals (either Ref 1 or Ref 2) and places it on the EF bus.
All other units that are linked together may use the EF bus reference as the reference