PSB2163T-V31TR Infineon Technologies, PSB2163T-V31TR Datasheet - Page 149

• 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
A signal burst fed into the loudspeaker amplifier appears after a short delay at the output
of the microphone amplifier (marked with a "1" in figure 8). Room echoes (marked with
"2") are significantly weaker and arrive later at the microphone. The resulting signal
envelope at the output of the microphone amplifier looks somehow like the bold line in
figure 8.
Therefore in first approximation the characteristic of the acoustical environment can be
described by a certain slope for the decrease of intensity of the echoes. But the
amplitude of the direct sound (signal part 1) arriving almost instantaneously at the
microphone depends on the amplification programmed for the ARCOFI-SP, the kind of
microphone and the loudspeaker used. As a consequence, the speech comparator for
the acoustic echo inside the ARCOFI-SP offers one parameter to compensate for these
amplifications (GAE, gain of the acoustic echo) and basically two additional parameters
to copy the acoustic properties of the room (GDAE, delta gain of the acoustic echo [dB]
and PDAE, peak decrement of the acoustic echo [dB/ms]). With these three parameters
the switching characteristic of the speech comparator is adjusted as shown in figure 9.
The characteristic is a picture of the acoustical phenomenons allowing a precise
differentiation between echo and true speech activity. Every signal whose level is above
the bold line in figure 9 will make the comparator to change state. If the signal level is
below the line, it must be regarded as an echo and no switching occurs.
Figure 9
Implementation of the Speech Comparator for the Acoustic Echo
Semiconductor Group
148