psb21391 Infineon Technologies Corporation, psb21391 Datasheet - Page 146

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

Data Sheet
4.4.5
The Automatic Gain Control of the receive direction AGCR (see figure 74) is similar to
the transmit AGC. One additional parameter (AAR) offers more flexibility since the
AGCR is able to attenuate signals as well. Depending on the parameters AAR and AGR
different behaviours of the AGCR are possible as figure 75 illustrates. For example with
AGR set to 0dB and AAR set to maximum (-48 dB) the AGCR acts as a limiter.
The AGCR is working only together with the speakerphone function (GCR.SP=1). The
digital gain stage LGAR is always enabled in speakerphone mode, independent of the
setting of GCR.AGCR.
It is highly recommended to program reasonable amplifications in the digital gain stages.
Otherwise the ASP will run into saturation above the 3.14 dB PCM-value.
Note that the speech detector for the receive direction is supplied with the signal that
comes out of the AGR-block unless XCR.PGCR = ’1’.
Figure 74
Function of the Receive AGC
Automatic Gain Control of the Receive Direction (AGCR)
136
PSB 21391
PSB 21393
2001-03-07
Codec