The Acoustic Echo Canceller (AEC) shall be fully automatic in its operation and shall not use any tones or noise in order to establish AEC convergence. The AEC shall operate at room gain levels of up to 10dB with a minimum total echo cancellation of 65dB. AEC convergence shall be no slower than 30dB / second. The AEC shall have a minimum echo cancellation span of 200 ms. The AEC shall, in addition to providing acoustic echo cancellation, provide up to 10 dB of ambient noise cancellation for the room. The noise cancellation shall effectively cancel steady-state ambient noise at all frequencies without causing any perceptible degradation of human voice or other transient sounds.
The AEC shall utilize balanced line level input and output, presented on XLR connectors, and shall have unbalanced auxiliary input and output available on RCA connectors. The microphone input shall permit microphone or line level signals. A mute switch contact closure option shall be available, which will permit muting of the room’s “send” audio without interruption of the receive path. Mute status shall be indicated by a front panel status indicator. Other than the mute switch option, no AEC controls of any kind will be accessible by users. Initial adjustments of send and receive levels shall be performed by the integrator and shall be available to the integrator only by removing the unit’s top panel. 28V phantom power shall be available for microphone inputs and shall be switch selectable.
The unit shall be powered by an external, UL approved supply providing +5, +15, and -15 VDC to the unit. The unit shall accept input voltage of 100 - 240 VAC, 50 / 60 Hz and shall consume no more than 40 Watts. The AEC shall be rack mountable and shall be sized so that up to two units may be fit in one rack space. The AEC shall comply with the ITU G.167 Recommendation for AEC, FCC part 15, and CE requirements.
The Polycom EF400 is specified.
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