The echo canceller shall be a multiple channel system with an integral automatic microphone and matrix mixer. Acoustic Echo Cancellation, AGC, EQ, and ambient noise cancellation shall be provided on each mic/line input channel.
The AEC shall have 12 inputs and 12 outputs. A total of 8 microphone / line inputs shall be provided. In addition, a 25 x 18 matrix mixer with four cross-point mix-minus sub-matrices shall be provided allowing for 32 independent simultaneous signals over the bus. Cross-points shall be gain adjustable in 1 dB increments over a range of +20 dB to -100 dB on the main matrix and over the expansion bus. The input section of the matrix shall include 8 mic/line inputs, 4 auxiliary inputs, 12 sums from mix minus expansion busses, and a signal generator. The output section of the matrix shall include 12 line level signals, two reference signals and 4 expansion busses. The expansion bus shall operate with a latency of less than 2ms, and all four channels on the expansion bus shall be capable of processing NOM (Number of Open Microphones) information.
An integral AGC (Automatic Gain Control) shall be provided on each mic/line input channel. The AGC shall use neural network processing to activate gain control on valid voice signals only. The AGC shall have controls to limit maximum and minimum gain levels as well as the speed of AGC movement. In addition, a 5-band parametric EQ shall be provided on each analog input and output channel. The unit shall provide two automatic microphone mixers, allowing the system to be split into two separate AEC systems, or two mixer zones.
The unit shall operate with a 22kHz bandwidth, 20 dB of headroom and 48 kHz sample rate in all operational modes. All input gains shall be adjusted in the analog stage before processing by the analog/digital converter. Settings to the gain levels shall be adjustable in 1 dB increments. AEC convergence shall be no slower than 40 dB / second. The AEC shall have a minimum echo cancellation span (tail time) of 270 ms per channel. The AEC shall be capable of operation at room gain levels of at least +10 dB. In addition, the unit shall provide user selectable amounts of ambient noise cancellation on each mic/line input up to 15 dB. The noise cancellation shall effectively cancel steady-state ambient noise at all frequencies without causing any noticeable artifacts, or perceptible degradation of the human voice. The noise cancellation shall automatically adapt and cancel new noise sources in less than 2 seconds.
The AEC shall be capable of front panel setup / control. Front panel controls will allow for the adjustment of level settings, presets and matrix cross points. Complete control of the unit and any connected unit including phone hybrids shall be available via a single RS-232 port. Any RS-232 port on the device chain shall be capable of controlling the entire chain. The unit shall ship with multiple pre-configured factory presets as well as user defined operational presets. All saved settings from Presets, Logic Inputs, Logic Outputs, and Macros shall be stored in non-volatile memory and shall require no battery backup. The system shall be capable of exporting all settings to create a hard copy or PDF based formatted report. A programmable logic interface shall be provided, with 24 logic inputs and 20 logic outputs. The system shall permit linking of up to 8 units to act as one system of 64 microphones, with control of NOM across all microphone channels in linked systems. The linked system of 8 units shall be capable of separating into 8 distinct microphone mixer groups with independent NOM control over each group.
The unit shall be powered by an external, UL approved supply providing +5 and +/-15 VDC. The AEC shall be no larger than one rack unit in size and shall comply with ITU G.167 Recommendation for AEC, FCC part 15, and CE requirements.
The ASPI Digital Vortex® EF2280 is specified.
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