PSB21382 INFINEON [Infineon Technologies AG], PSB21382 Datasheet - Page 159

• Manufacturer Part Number: PSB21382
• Description: Siemens Codec with S/T Transceiver
• Manufacturer: INFINEON [Infineon Technologies AG]

Figure 86
Level Diagram For the AGC in Receive Direction
If the speakerphone is in transmit mode, the AGCR is not working; instead the last gain
setting is used and the regulation starts with this value when the speakerphone has gone
back into receive mode again.
The initial attenuation (AGIR) is used immediately after enabling the AGCR to allow a
fast settling time of the AGC.
The sweep range of the switchable attenuation ATT is affected by the AGCR. If the
automatic gain control enlarges or reduces the signal level, the sweep range will be
adjusted automatically in a way, that the over-all gain in transmit and receive direction
remains constant (constant TCL, constant echo return loss).
Because of this the AGCR can be used for a comfortable receive volume control where
the TCL value is the same for each volume setting and thus providing an optimal
speakerphone performance. For such a volume control the momentary attenuation of the
AGCR has to be read out by a SOP_D command. The parameters AGIR, COMR, can
be determined for the desired volume change and written back in the CRAM.
Data Sheet
AGR=0...+18dB
AAR=0...-48dB
-50dBm0
AGR>0
-40dBm0
AGR=0
AGC INPUT LEVEL
-30dBm0
-20dBm0
AGR+|AAR|
149
-10dBm0
MAX. PCM
COMR
-40dBm0
-10dBm0
-20dBm0
-30dBm0
-50dBm0
MAX. PCM
PSB 21381/2
PSB 21383/4
RKEN.DRW
2001-03-12
OUTPUT
LEVEL
AGC
Codec