DEFINITION OF TERMS

EF Bus

Equalization

Line Echo

Macros Matrix Mixer

Noise Cancellation

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.

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 EF2241 is an example of a device that includes a line echo canceller.

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 noise cancellation algorithm (patent pending) is capable of removing 10 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

NOM Attenuation

NOM Bus

Presets

Room Gain

NOM refers to the number of open microphones in a system.

NOM attenuation is the gain applied to the overall system gain to the microphone sig- nals to compensate for how many microphones are open. The amount of attenuation is calculated by 10*log10(NOM).

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.

The room gain of a conferencing system refers to the relative levels of the signal sent to the line output to your amplifier (before any amplification) and the level of this sig- nal that is reflected at the microphone input (after microphone amplification). If the electrical level of the reflected signal picked up by the microphone is the same as the level of the electrical signal sent from the AEC to the line output to your amplifier, the

VORTEX EF2241 Reference Manual

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Polycom EF2241 manual Nom, NOM Attenuation NOM Bus Presets Room Gain