Polycom EF2201 Brochure & Specs page 13

How do I access it?
The processing is most easily accessed via RS-232 commands. Conference Composer simplifies the process of enabling
the processing and configuring the necessary parameters. The user can also design the filters by setting the appropriate
frequencies, bandwidths, and attenuation/gain values.
Where can I apply it?
The input equalization can be used to compensate for varying characteristics of microphones or input room conditions.
The AGC can help compensate for loud or soft talkers. The noise cancellation can help remove background noise.
What is a parametric EQ? Why would I use it? How do I use it?
Parametric equalization is a technique for applying filters where you need them with arbitrary gains and center
frequencies. This differs from graphic equalizers where the filters have fixed bandwidth and center frequencies. You
might use this to compensate for different microphone frequency characteristics, to compensate for some background
noise such as a 60Hz hum, or to remove some of the room effects.
When would I use a high/low pass filter? How does it work?
You might use a highpass filter to remove some low frequencies such as some boominess in a room. A lowpass filter
could be used to remove high frequency background noise (as well as any desired signal in the same frequency band).
When using InstantDesigner, a 80 Hz highpass filter will be enabled on each microphone input signal to reduce the room
boominess.
Bussing Questions
The EF Bus is used to send high-speed data and control between Vortexes devices.
How does the bussing work?
Within the EF bus there are five busses: the P, W, X, Y, and Z busses. Each of these busses contains up to 8 signals (one
from each linked Vortex). Each Vortex can place an output signal on each of the P, W, X, Y, and Z busses. The P bus
output is only found on the telephony devices and is typically used to transmit the phone signal ('P' for phone) between
devices. Since there can be 8 Vortexes linked, this means there are a total of 32 signals on the EF bus at any given time
and each linked Vortex can get any of these signals off the bus. With the addition of the P bus on the telephony
products, up to 8 EF2280's and 8 EF2201's can be linked together for a total of 16 devices. The W, X, Y, and Z busses
include NOM information and are most often used to link microphones between devices, but can also be used to share
line level sources between devices.
What is the sub-matrix? And how many are there?
The sub-matrix is a smaller matrix that feeds the main matrix. The inputs to the sub-matrix are the bus signals from all
the other devices that are linked. In the Vortex there are five sub-matrices, one for each of the P, W, X, Y, and Z busses.
Each sub-matrix has 7 inputs (the maximum number of devices that can be linked to any given device). Since a device's
bus cannot be linked to itself, there are only 7 inputs, not 8 to each sub-matrix. In the Vortex, each sub-matrix for the W,
X, Y, and Z busses has 3 outputs and the sub-matrix for the P bus has 2 outputs, which become inputs to the main matrix.
Any of the three outputs from each sub-matrix can have arbitrary cross points applied to them so you can weight the
signals from other devices to enable arbitrary zoning or mute some of them to extract just the signals from the bus that
you want.
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