PSB2163T-V31TR Infineon Technologies, PSB2163T-V31TR Datasheet - Page 153

• Manufacturer Part Number: PSB2163T-V31TR
• Description: IC AUDIO RINGING CODEC 28-PDSO
• Manufacturer: Infineon Technologies
• Series: ARCOFI®r

Specifications of PSB2163T-V31TR

• Function: CODEC Filter
• Interface: IOM-2, PCI, Serial
• Number Of Circuits: 1
• Voltage - Supply: 5V
• Current - Supply: 900µA
• Power (watts): 1mW
• Operating Temperature: -25°C ~ 80°C
• Mounting Type: Surface Mount
• Package / Case: DSO-28
• Includes: Activation and Deactivation, B-Channel and D-Channel HDLC Controllers, D-Channel Priority Handler, Monitor Channel Handler
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Other names: PSB2163T-V31INTR; PSB2163T-V31TR

Speakerphone Implementation
2.7
The Speech Comparator for the Line Echo
Having understood the task and principle of the comparator for the acoustic echo
(SCAE) the understanding of the speech comparator for the line echo (SCLE) is easy. As
shown in figure 2, the speakerphone has not only to deal with acoustic couplings but
also with echoes coming from the network. Basically, the intensity of echoes resulting
from reflections somewhere inside the telecommunication network or from the acoustic
connected to the far end, decreases exponentially. Therefore a comparator that has to
cover the line echo must show a characteristic similar to the one shown in figure 9 for
the acoustic echo.
The implementation of the SCLE is identical to the one of the SCAE and therefore all
explanations given in chapter 2.6 apply also to the comparator for the line echo. The
parameters to be used are different and result from the following considerations
(compare with the block diagram of the SCLE in figure 11).
Experience shows that in worst case the level of the echo coming from the line can be
about 10dB below the sending level. This level difference must be compensated with the
gain of the line echo (GLE) to get the same input conditions at the dashed line in
figure 11. Besides, the line echoes can show a significant long delay in the range of
some 100ms depending on the kind of connection used (consider satellite links). By
choosing a slow slope for the peak decrement PDLE and a high value for the delta gain
GDLE these echoes can be covered (see typical values in table 3).
Figure 11
Block Diagram of the Speech Comparator for the Line Echo
Semiconductor Group
152