Polycom EF2241 manual Set Up The Phone Interface, Build Your Echo Canceller Reference

INTEGRATING THE EF2241 INTO YOUR SYSTEM

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.

SET UP THE PHONE INTERFACE

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.

BUILD YOUR ECHO CANCELLER REFERENCE

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,

If your system has 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.

•Do NOT mix your room microphones into the reference, but include all other audio (program audio, remote audio, phone audio, etc.).

ECHO CANCELLER REFERENCE FOR MULTIPLE VORTEX DEVICES

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

© Polycom, Inc. 17 VORTEX EF2241 Reference Manual