User Manual

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USERS MANUAL
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Document number Revision
4/198 17-LXE 108 566 Uen PA6
2.6.2 Analog Audio
ATMS is the analog audio input to the module. When it is active, it is connected to the
radio via the audio processing stages in the module.
The AFMS is the analog audio output from the module. When it is active it is connected
to the radio via the audio processing stages in the module.
The AGND is the analog reference signal. ATMS and AFMS are referenced to this
signal, which is connected to GND in one place inside the module.
Pin Signal Description
7
AFMS Audio Output From Module
10
ATMS Audio Input To Module
9
AGND Analog Reference
Table 13: CM52 Analog Audio Signals
Signal Parameter
Module audio output
300 – 3400 Hz
Output Impedance
Rout 100 
Drive capacity into 10 k
3.77 V
P-P
max. or 2.5 dBV
External Device audio input
impedance
Zin  10 k
Volume control
-81 dB from maximum > - 81 dB (mute)
AFMS
Sensitivity
1004 Hz tone at 8kHz deviation
generates 900+
100 mV
rms
.
Sources are preferably AC
coupled.
Cout  2.2uF
External Device audio source
Output resistance
Rout  1.0 k
Module audio input impedance
Zin  10 k
Levels from external audio
source (maximum)
3.77 V
P-P
max. or 2.5 dBV
ATMS
Sensitivity
1004 Hz tone at 900+100 mV
rms
generates 8kHz deviation.
Table 14: Audio Characteristics
Analog Reference (AGND)
• The AGND lead is the analog audio reference ground. It is the return signal for
Audio To Mobile Station (ATMS), Audio From Mobile Station (AFMS).
• Electrical characteristics
: I
max
< 40 mA (peak)
• The AGND is connected to the chassis Ground (GND) in the CM52 module, and
only there. The application should be connected to GND and only use AGND as
reference for the audio lines ATMS and AFMS.
• The PCM signals are referenced to digital ground.