psb21391 Infineon Technologies Corporation, psb21391 Datasheet - Page 143

• Manufacturer Part Number: psb21391
• Description: Siemens Codec With Upn Transceiver
• Manufacturer: Infineon Technologies Corporation

Description of the programmable parameters:
Parameter
GLE
GDSLE
PDSLE
GDNLE
PDNLE
ETLE
4.4.4.3
Optionally an AGCX is inserted into the transmit path (see figure 72) to reach nearly
constant loudness ratings independent from the varying distance between the speaking
person and the microphone. The AGCX works only together with the speakerphone
function (GCR.SP=1).
Operation of the AGCX depends on a threshold level. The threshold is defined by the
parameter COMX (value relative to the maximum PCM-value). Regulation follows two
time constants: TMHX for signal amplitudes above the threshold and TMLX for
amplitudes below. Usually TMHX will be chosen up to 10 times faster than TMLX. The
bold line in figure 73 depicts the steady-state output level of the AGCX as a function of
the input level.
Figure 72
Block Diagram of the AGC in Transmit Direction
Data Sheet
Automatic Gain Control of the Transmit Direction (AGCX)
# of CRAM
Bytes
1
1
1
1
1
1
Range
– 48 to + 48 dB
0 to 48 dB
0.16 to 42 ms/dB
0 to 48 dB
0.16 to 42 ms/dB
0 to 1020 ms
133
Comment
Gain of Line Echo
Reserve when speech is detected
Peak Decrement
when speech is detected
Reserve when noise is detected
Peak Decrement
when noise is detected
Echo time
PSB 21391
PSB 21393
2001-03-07
Codec