User Guide

GE9
GE9GE9
GE910 Hardware User Guide
10 Hardware User Guide10 Hardware User Guide
10 Hardware User Guide
1vv0300962 Rev.4 2012-06-25
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 49 of 73
Mod. 0805 2011-07 Rev.2
10.3. EAR connection
The audio output of the GE910 is balanced, this is helpful to double the level and to reject
common mode (click and pop are common mode and therefore rejected).
These outputs can drive directly a small loudspeaker with electrical impedance not lower than
8Ohm.
TIP: in order to get the maximum audio level at a given output voltage level (dBspl/Vrms), the
following breaking through procedure can be used. Have the loudspeaker as close as you can to
the listener (this simplify also the echo cancelling); choose the loudspeaker with the higher
sensitivity (dBspl per W); choose loudspeakers with the impedance close to the limit (ex: 16 or 8
Ohm), in order to feed more power inside the transducer (it increases the W/Vrms ratio). If this
were not enough, an external amplifier should be used.
EAR+
EAR-
MODULE
MODULEMODULE
MODULE
-
+
OUTPUT
DAC