Specifications

TC35 / TC37 Hardware Interface Description
TC35_37_HD_02_V03.10 - Released Page 80 of 92 21.12.2001
6.5 Electrical characteristics of the voiceband part
6.5.1 Setting audio parameters by AT commands
Each audio mode is assigned a separate set of parameters. The audio modes 2 to 6 can be
adjusted according to the parameters listed below. Audio mode 1 is the default configuration
which cannot be modified.
Table 34: Audio parameters adjustable by AT command
Parameter Influence to Range Gain range Calculation
inBbcGain MICP/MICN analogue amplifier gain
of baseband controller before ADC
0...7 0...42dB 6dB steps
inCalibrate digital attenuation of input signal
after ADC
0...32767 -#...0dB 20 * log
(inCalibrate/
32768)
outBbcGain EPP/EPN analogue output gain of
baseband controller after DAC
0...3 0...-18dB 6dB steps
outCalibrate[n]
n = 0...4
digital attenuation of output signal
after speech decoder, before
summation of sidetone and DAC
present for each volume step[n]
0...32767 -#...+6dB 20 * log (2 *
outCalibrate[n]/
32768)
sideTone digital attenuation of sidetone
is corrected internally by outBbcGain
to obtain a constant sidetone
independent of output volume
0...32767 -#...0dB 20 * log
(sideTone/
32768)
Note: The inCalibrate, outCalibrate and sideTone accept also values from 32768 to 65535.
These values are internally truncated to 32767.
The following figure illustrates how the signal path can be influenced by varying the AT
command parameters.
A
D
A
D
-
∞
...0dB
speechcoder
(0dB; -6db,
-12dB; -18dB)
+0..42dB in
6dB-ste
p
s
1k
1k
1k
1k
2,65V
10uF
6,8R
6,8R
+
sideTone
A
T - parameter
outCalibrate[n]
n = 0...4
inCalibrate
inBbcGain
outBbcGain
speechdecoder
Figure 43: AT audio programming model