User's Manual

MC55/56 Hardware Interface Description
Confidential / Preliminary
s
MC55/56_hd_v03.00 Page 87 of 104 16.08.2005
5.5.3 Characteristics of audio modes
The electrical characteristics of the voiceband part depend on the current audio mode set
with the AT^SNFS command.
Table 29: 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
4 (24dB)
1 (-6dB)
Adjustable
2 (12dB)
1 (-6dB)
Adjustable
5 (30dB)
2 (-12dB)
Adjustable
4 (24dB)
1 (-6dB)
Adjustable
0 (0dB)
0 (0dB)
Adjustable
0 (0dB)
0 (0dB)
Default audio
interface
1 2 2 1 1 2
3)
Power supply
ON (2.65V) ON (2.65V) ON (2.65V) ON (2.65V) OFF (GND) OFF (GND)
Sidetone ON --- Adjustable Adjustable Adjustable Adjustable
Volume control OFF Adjustable Adjustable Adjustable Adjustable Adjustable
Limiter (receive) ON ON ON ON --- ---
Compressor
(receive)
--- OFF
1)
--- --- --- ---
AGC (send) --- --- ON --- --- ---
Echo control (send) Suppression Cancellation +
suppression
--- Suppres-
sion
--- ---
Noise suppression
2)
--- up to 10dB 10dB --- --- ---
MIC input signal for
0dBm0 @ 1024 Hz
(default gain)
23mV 58mV 7.5mV @
-3dBm0 due
to AGC
23mV 315mV 315mV
EP output signal in
mV rms. @ 0dBm0,
1024 Hz, no load
(default gain);
@ 3.14 dBm0
284mV 120mV
default @
max volume
300mV
default @
max volume
284mV
default @
max
volume
895mV
3.7Vpp
895mV
3.7Vpp
Sidetone gain at
default settings
22.8dB - dB Affected by
AGC, 13dB
@ 7.5mV
(MIC)
22.8dB
- dB - dB
1)
Adaptive, receive volume increases with higher ambient noise level. The compressor can be
activated by loading an application specific audio parameter set (see [9]).
2)
In audio modes with noise reduction, the microphone input signal for 0dBm0 shall be measured
with a sine burst signal for a tone duration of 5 seconds and a pause of 2 sec. The sine signal
appears as noise and, after approx. 12 sec, is attenuated by the noise reduction by up to 10dB.
3)
Audio mode 5 and 6 are identical. With AT^SAIC, you can easily switch mode 5 to the second
interface. Therefore, audio mode 6 is only kept for compatibility to earlier Siemens GSM products.