User's Manual
Table Of Contents
- Contents
- Figures
- Tables
- Document history
- Introduction
- Product concept
- GSM application interface
- GSM/GPRS operating modes
- Power supply
- Power up / down scenarios
- Automatic GPRS Multislot Class change
- Charging control of the GSM part
- Power saving
- Summary of state transitions (except SLEEP mode)
- RTC backup for GSM part of XT55/56
- Serial interfaces of the XT55/56 GSM part
- Audio interfaces
- SIM interface
- Control signals
- GPS application interface
- GSM and GPS antenna interfaces
- Electrical, reliability and radio characteristics
- Mechanics
- Reference approval
- Example applications
- List of parts and accessories
XT55/56 Hardware Interface Description
Confidential / Released
s
XT55/56_hd_v02.06a Page 103 of 125 17.12.2004
6.5.2 Audio programming model
The audio programming model shows how the signal path can be influenced by varying the
AT command parameters. The model is the same for all three interfaces, except for the
parameters <outBbcGain> and <inBbcGain> which cannot be modified if the digital audio
interface is being used, since in this case the DAC is switched off.
The parameters inBbcGain and inCalibrate can be set with AT^SNFI. All the other
parameters are adjusted with AT^SNFO.
A
D
A
D
-
∞
...0dB
Speech coder
neg. gain (attenuation)
0dB; -6db, -12dB; -18dB
+0...42dB in 6dB steps
1k
1k
1k
1k
2.65V
10uF
+
<sideTone>
A
T parameters are given in brackets <…>
and marked red and italic.
<outCalibrate[n]>
n = 0...4
<inCalibrate>
<inBbcGain>
<outBbcGain>
Speech decoder
GSM_MIC2
GSM_TFSDAI, GSM_TXDDAI
GSM_RFSDAI, GSM_RXDDAI
GSM_MIC1
<io>
<ep>
<mic>
Figure 48: AT audio programming model