MC55i Terminal Hardware Interface Description
3.7 Audio Interface
32
MC55i_Terminal_HD_v01.201a
Page 26 of 47
2010-04-16
Confidential / Released
3.7
Audio Interface
The audio interface provides an analog input for a microphone and an analog output for an ear-
piece.
•
The microphone input and the earpiece output are balanced.
•
For electret microphones a supply source is implemented.
•
The microphone supply characteristics are optimized for the recommended Votronic hand-
set. This handset has been used as the reference handset for type approval (see
). An extra approval must be obtained for integrating other handsets or amplifiers.
The amplification of sending direction, receiving direction and sidetone depend on the current
audio mode.
EMC immunity complies with the vehicular environment requirements according to
EN 301 489-7.
Figure 6:
Audio Western plug (4-pole female)
Figure 7:
Audio block diagram
Pin assignment:
1 MICN (Microphone - )
2 EPN (Earpiece)
3 EPP (Earpiece)
4 MICP (Micr )
1
2
3
4
A
D
A
D
...0dB
speechcoder
0dB;-6dB;-12dB;-18dB
+0...42dB in
6dB - steps
4k7
4k7
5.9V
6R8
6R8
+
(sideTone)
( ) AT parameter
( outCalibrate[n])
n=0...4
(inCalibrate)
(inBbcGain )
(outBbcGain )
speechdecoder
Ri=9k
MICP
MICN
EPP
EPN
8
-
