D. OPTIONS
D-2
BeFREE 20 – TECHNICAL OVERVIEW
D.3.
Echo-Cancellation Circuitry
Acoustic echo is a physical phenomenon inherent to hands-free devices (such as
Intercom) in full-duplex mode, so it needs to be suppressed and/or cancelled. This is
normally implemented in the application software through the specific signal processing
routines. Alternatively, it can be achieved in the hardware using a digital signal processor.
Basic properties of the optional (see Chapter E.1 for details on the respective Ordering
Code) Echo-Cancellation circuitry are listed below.
♦
performance
: full-duplex
♦
sampling rate
: 16 kHz
♦
acoustic echo-cancellation
:
≥
40 dB
♦
latency
:
≤
10 ms
Reference signal for the canceller is the sum of signals at the left and the right speaker.
Optionally, the reference might be taken from either of the Speakers.
D.4.
Goose-Neck Microphone
By default, the goose-neck microphone is an integral part of the BeFREE 20, but it can
be optionally omitted. See Chapter E.1 for details on the respective Ordering Code.
