Echo Cancellation; Noise Reduction; Handsfree Components; Cradle - Ericsson EF738 Service Manual

Accessories

Echo Cancellation

To avoid acoustic feedback in a full duplex handsfree system, i.e. prevent the
speaker sound being picked up by the microphone from becoming amplified, the
DSP has to suppress these signals by Echo Cancellation. The DSP will be able to
distinguish transmitted speech from received echoed speech, if it is informed about
the acoustic environment of that particular vehicle where the handsfree kit is
installed. This is automatically done by an adaptive training sequence which is
being continuously updated.

Noise Reduction

The ambient noise of a driven vehicle is often too loud to allow an acceptable
speech quality when using handsfree. The DSP is however able to separate this
noise from the speech and reduce it to an acceptable level.

HandsFree Components

Cradle

The Cradle consists of two sub-units, the Cradle Attachment and the Holder
The Cradle is equipped with a slide joint which is adjusted during the installation to
a suitable vertical and horizontal angle for easy reach of the phone. The snap/click-
in Holder connects the phone to the HandsFree Unit.

Stick-On Microphone

The Stick-On Microphone included in the kit is a unidirectional microphone to be
mounted in a fixed position in the vehicle and connected to the HandsFree Unit.
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Cradle Attachment
Holder