The RB-AEC is primarily designed for the benefit of studio personnel in television and radio. When a studio presenter's microphone signal is played out through a monitor speaker in the control room, it can be picked up by the control room microphone(s) and returned to the presenter's earpiece as an undesirable echo. This unit 'learns' the environment and can be used to remove the echo from the earpiece, using digital processing.
In circumstances where green-screen video processing is taking place, the delay can be greater than 200ms. Additionally, the dimensions, occupancy and distance between mouth and microphone can further influence the echo. The RB-AEC is used to remove the entire output of the control-room monitor-speaker from the presenter's feed, by adapting to the environment in which the control-room microphones are placed. Although acoustic echo cancellation is more commonly implemented in telephony systems, the Sonifex RB-AEC is designed to produce broadcast quality cancellation.
The post-processed transmission output program from the studio (A) is sent to the RB-AEC as an analogue or digital audio signal (the stereo input is auto-sensing) which 'acts as a mix-minus to the input signal (B) from the control room'. The RB-AEC removes the unwanted acoustic echoes so that the audio sent to the presenter's earpiece (C) is free of echoes and reflection artifacts.
The device may also be used during a 'phone-in' to remove delayed caller audio from the telephone line.
The unit can be controlled remotely over an Ethernet connection using the built-in web server. By default the unit is configured for dynamic addressing using DHCP and 'Auto-IP'. If a static IP address is required then this must be configured through the web server.
The device is packaged in the familiar Sonifex Redbox rack-mounting chassis, IU high. The front panel has an LED to indicate power.
The rear panel has two 3-pin, female, XLR connectors for the line level analogue or digital inputs for the 'far end' and 'near end'. Three 3-pin, male, XLR connectors provide analogue outputs one and two as well as the digital output. A bank of four miniature (DIL) switches adjust settings, a 9-pin, female, D-sub connector provides GPIO connections and an RJ45 connector is provided for Ethernet. Power is connected via an IEC inlet, with an adjacent fuse.
Audio inputs: +18dBu / 0dFS maximum, 20k ohms / 110 ohms with termination set, analogue / digital. Input gain: 0, +6, +12 or +18dB digital gain, switchable. Distortion: 0.02%, 1kHz, +8dBu output. Noise: -84dB RMS, unity gain, ref +8dBu output. Response: 20Hz-12kHz +0/-0.5dB. Rejection ratio: Typically 20dB input to output on complex waveforms, reference peak level of 0dB. Audio outputs: +18dBu / 0dFS maximum, 50 ohms / 110 ohms, analogue / digital. Output sample rates: 32kHz - 192kHz, selectable. Power source: 85-264V AC, 47-63Hz, 10W maximum. Dimensions: 480 x 108 x 42 (w x d x h). Weight: 1.5kg.
Included accessories: Manual, AC power cable.
Optional accessories: RB-RK3 Rear rack panel kit.