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AC75 Hardware Interface Description
Strictly confidential / Preliminary
s
AC75_HD_V00.202
Page 98 of 120
27.04.2006
5.7.3 Characteristics of Audio Modes
The electrical characteristics of the voiceband part depend on the current audio mode set
with the AT^SNFS command. All values are noted for default gains e.g. all parameters of
AT^SNFI and AT^SNFO are left unchanged.
Table 31: Voiceband characteristics (typical)
Audio mode no.
AT^SNFS=
1 (Default
settings, not
adjustable)
2
3
4
5
6
Name
Default
Handset
Basic
Handsfree
Headset User
Handset
Plain
Codec 1
Plain
Codec 2
Purpose
DSB with
Votronic
handset
Siemens
Car Kit
Portable
Siemens
Headset
DSB with
individual
handset
Direct access
to speech
coder
Direct access
to speech
coder
Gain setting via AT
command. Defaults:
inBbcGain
outBbcGain
Fix
5 (30dB)
1 (-6dB)
Adjustable
2 (12dB)
2 (-12dB)
Adjustable
5 (30dB)
1 (-6dB)
Adjustable
5 (30dB)
1 (-6dB)
Adjustable
0 (0dB)
0 (0dB)
Adjustable
0 (0dB)
0 (0dB)
Default audio
interface
1 2
2
1
1 2
Power supply VMIC
ON ON
ON
ON
ON ON
Sidetone
Fix ---
Adjustable
Adjustable
Adjustable
Adjustable
Volume control
Fix Adjustable
Adjustable
Adjustable Adjustable Adjustable
Echo control
Echo canceller
ON ON
ON
ON
OFF
OFF
Loss controller
idle/full attenuation
3dB / 6dB
4dB / 50dB
9dB / 18dB 3dB / 6dB
OFF
OFF
Comfort noise
generator
ON ON
ON
ON
OFF
OFF
Non linear processor ON ON
ON
ON
OFF
OFF
MIC input signal for
0dBm0
-10dBm0
f=1024 Hz
18mV
5.8mV
---
95mV
---
14mV
18mV
5.8mV
400mV
126mV
400mV
126mV
EP output signal in
mV rms. @ 0dBm0,
1024 Hz, no load
(default gain) /
@ 3.14 dBm0
475mV 70mV
default @
max volume
270mV
default @
max volume
475mV
default @
max volume
1.47V
Vpp = 6.2 V
1.47V
Sidetone gain at
default settings
21.9dB -
∞
dB
10.0dB
21.9dB
-
∞
dB
-
∞
dB
NOTE: With regard to acoustic shock, the cellular application must be designed to avoid
sending false AT commands that might increase amplification, e.g. for a highly sensitive
earpiece. A protection circuit should be implemented in the cellular application.
9
Audio mode 5 and 6 are identical. AT^SAIC can be used to switch mode 5 to the second interface. Audio mode
6 is therefore kept mainly for compatibility to earlier Siemens GSM products.
10
In audio modes with an active loss controller a continuous sine signal is attenuated by the idle attenuation after
a few seconds. All input voltages are noted for the idle attenuation. If the idle attenuation is higher than 3 dB,
0dBm0 cannot be reached without clipping. In this case only the value for -10dBm0 is noted.