psb21391 Infineon Technologies Corporation, psb21391 Datasheet - Page 137

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

Description of the programmable speech detector parameters:
Parameter
LP1
OFF
PDS
PDN
LP2S
LP2N
LP2L
LIMX, LIMR
4.4.4
Switching from one active mode to another one is controlled by the speech comparators,
provided the speech detectors are indicating speech. There are two speech
comparators, one at the acoustic (AE) and one at the line side (LE). These comparators
continuously compare the signal levels of both signal paths and control the effect of the
echoes at the acoustic side and the line side. Once speech activity has been detected,
the comparator switches at once in that direction in which the speech signal is stronger.
For this purpose each signal is compared to the sum of the other and the returned echo.
Data Sheet
Speech Comparators (SC)
# of CRAM
Bytes
1
1
1
1
1
1
1
1
Range
1 to 512 ms
0 to 50 dB
1 to 512 ms
1 to 512 ms
4 to 2000 ms
1 to 512 ms
0 to 95 dB
– 36 to – 78 dB
127
Comment
Time constant LP1
Level offset up to detected noise
Time constant PD (signal)
Time constant PD (noise)
Time constant LP2 (signal)
Time constant LP2 (noise)
Limitation of LP2, related to LIM
Limitation of logarithmic amplifier
PSB 21391
PSB 21393
2001-03-07
Codec