User's Manual

CE910-DUAL Hardware User Guide

1vv0301010 Rev .0 – 2012-07-10

9. Audio Section Overview

The CE910-DUAL provides one differential input for audio to be transmitted(Uplink) and a

balanced output for audio to be received(Downlink).

The bias for the microphone has to be as clean as possible; the first connection (single ended)

is preferable since the Vmic noise and ground noise are fed into the input as common mode

and then rejected. This sounds strange; usually the connection to use in order to reject the

common mode is the balanced one. In this situation we have to recall that the microphone is a

sound to current transducer, so the resistor is the current to tension transducer, so finally the

resistor feeds the input in balanced way even if the configuration, from a microphone point of

view, seems to be un-balanced.