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

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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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Technical Support: 800.932.2774

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Contents Vortex EF2241 Reference Manual Page Introduction Welcome How to Use This Manual IntroductionProduct Product FeaturesProduct Registration Inputs Outputs Remote Control What’s Included PRE-INSTALLATIONTools Needed for Installation What’s Not IncludedEF2241 Front and Rear Panels PRE-INSTALLATION Mounting the EF2241 InstallationConnecting the EF2241 to Other Equipment North American RequirementTypical EF2241 Connections CodecConnecting Multiple Vortex Devices Device IDS on the EF BUSFactory Default Settings Preset Terminating the EF2241Off Check Surrounding Equipment Presets Multiple Vortex DevicesPick a Standard Signal Level Configure Program Audio Sources Calibration Input SettingsIntegrating the EF2241 Into Your System Set Levels on Line Input Channels Echo Canceller Reference for Multiple Vortex Devices SET UP the Phone InterfaceBuild Your Echo Canceller Reference Customize Setting for Your Particular ApplicationSetting up Bus ReferenceConfigure the Automatic Microphone Mixer Automixer ParametersGlobal Settings Automixer Settings for Multiple Vortex Devices Channel SettingsBuilding Your System with Multiple Vortex Devices Configure the Matrix MixerDefault Settings Configure the submatrix Assign Inputs Assign OutputsEF BUS Configure Your Echo Canceller Reference PresetsOther EF2241 Features LCD Menu Structure LCD Menu TreeLCD Menu Structure System Menu SystemPhone Control Phone ControlInputs Inputs 1-4, T, A-DOutputs Automixer MenuGlobal Settings Mixer Settings Matrix Menu MatrixParametric EQ Menu Input/Output EQ Channel BandPresets MacrosNo microphones are gating Some microphones are not gating TroubleshootingAutomatic Microphone Mixer Too many microphones are gatingResidual Echo Echo Canceller ReferenceMatrix Mixer Room Audio Sounds ChoppyFinding the Source of Echo Room Gain Excessive Room Gain Room GainIn-Conference Quick Check Excessive Microphone Amplification Insufficient NonlinearityContacting Technical Support Email vortex@polycom.comTechnical Specifications US Telco requirements ComplianceUSA and Canada Automatic Dialing Telco Connector Canadian Telco RequirementsAustralia Rest of WorldThis page was intentionally left blank CE Mark R& TTE Directive Vortex EF2241 Reference Manual Technical Support Conference System Design Noise and Reverberation Consider Room GainEF2241 Block Diagram EN Echo Canceller, Noise CancellerConnector Pinouts EF BusInput/Output Remote Control Port Instructions Connecting Unbalanced RCA to Balanced Mini PhoenixMaking AN EF BUS Terminator Additional Notes Warranty Information RMA# Must be on packageWhat this warranty does not cover State Law RightsAcoustic Echo Echo CancellerDefinition of Terms Crosspoint Mix Minus BusNOM Attenuation NOM Bus Presets Room Gain NOMDefinition of Terms Index NOM Index Page 1725-80098-001-C