Polycom Vortex EF2280 Reference Manual page 68

EF Bus
Equalization
Line Echo
Macros
Matrix Mixer
Noise
Cancellation
NOM
NOM Attenuation
NOM Bus
Presets
V EF2280 Reference Manual
ORTEX
The EF Bus is a digital bus that includes the W, X, Y, and Z audio busses as
well as the echo canceller reference and remote control information. It can be
used to link multiple Vortex devices. This Bus is self terminating and does not
require a separate terminator.
Equalization is the process of adjusting frequency characteristics of an audio
signal.
Line echo is caused by reflections of the audio signal from the telephone
hybrid. The EF2201 is an example of a device that includes a line echo cancel-
ler.
An arbitrary set of commands that can be replayed.
A matrix mixer allows you to choose which inputs are included in each output.
Some matrix mixers allow you to assign crosspoint gains to the inputs.
Noise cancellation is a digital signal process that removes noise from an audio
signal corrupted by real-world interferences such as HVAC, office noise, crowd
noise, or road noise. Generally, there are two parts of a noise cancellation
algorithm: a method to detect the noise and a method to remove the noise.
The Polycom patented noise cancellation algorithm is capable of removing 15
dB or higher of noise with no degradation at all to the resulting speech signal.
This method does not attenuate speech, and removes noise during both
speech and idle periods.
NOM refers to the number of open microphones in a system.
NOM attenuation is the gain applied to the overall system gain to the micro-
phone signals to compensate for how many microphones are open. The
amount of attenuation is calculated by 10*log
A NOM bus carries signal information as well as NOM information (i.e., the
number of open microphones in the system, NOM).
Presets correspond to configuration parameters that have been previously
saved to EEPROM.
66
D
EFINITION OF
(NOM).
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