PSB21473FV13XT Infineon Technologies, PSB21473FV13XT Datasheet - Page 389

• Manufacturer Part Number: PSB21473FV13XT
• Manufacturer: Infineon Technologies

Specifications of PSB21473FV13XT

• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 3.135V
• Operating Supply Voltage (max): 3.6V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 144
• Lead Free Status / RoHS Status: Compliant

To control the acoustic feedback two parameters are necessary: GD represents the
actual reserve on the measured G. Together with the Peak Decrement (PD), the echo
behavior at the acoustic side is modeled: After speech has ended there is a short time
during which hard couplings through the mechanics and resonances and the direct echo
are present. Till the end of that time (
to G to prevent clipping caused by these internal couplings. After that time (
acoustic feedback is present. This coupling, however, is reduced by air attenuation. For
this in general the longer the delay, the smaller the echo being valid. This echo behavior
is taken care of by the decrement rate PD.
Figure 20-15 Speech Comparator - Interdependence of Parameters
According to figure 20-15, a compromise between the reserve GD and the decrement
PD has to be made: a smaller reserve (GD) above the level enhancement G requires a
longer time to decrease (PD). It is easy to overshout the other side but the
intercommunication is harder because after the end of the speech, the level of the
estimated echo has to be exceeded. In contrary, with a higher reserve (GD*) it is harder
to overshout continuous speech or tones, but it enables a faster intercommunication
because of a stronger decrement (PD*).
Two pairs of coefficients, GDS/PDS when speech is detected, and GDN/PDN in case of
noise, offer a different echo handling for speech and non-speech. With speech, even if
very strong resonances are present, the performance will not be worsened by the high
GDS needed. Only when speech is detected, a high reserve prevents clipping.
Data Sheet
dB
RX-noise
GD*
GD
RX-Speech
G
PD*
t
t
), the level enhancement V must be at least equal
389
G
PD
Digital Signal Processor
PSB 21473
t
t
2003-03-31
), only the
INCA-D