PEB3265 Infineon Technologies Corporation, PEB3265 Datasheet - Page 70

• Manufacturer Part Number: PEB3265
• Description: (PEB326x / PEB426x) Dual Channel Slicofi-2 / Slic Duslic
• Manufacturer: Infineon Technologies Corporation

Preliminary
If the adaptation of the shadow filter is performed better than the adaption of the actual
filter by a value of more than DeltaQ then the shadow filter coefficients will be copied to
the actual filter.
At the start of an adaption process the coefficients of the LEC unit can be reset to default
initial values or set to the old coefficient values. The coefficients may also be frozen.
3.8.4
Each channel of the DuSLIC has two Universal Tone Detection units which can be used
to detect special tones in the receive and transmit paths, especially fax or modem tones
(e.g., see the modem startup sequence described in recommendation ITU-T V.8).
This allows the use of modem-optimized filter for V.34 and V.90 connections. If the
DuSLIC UTD detects that a modem connection is about to be established, the optimized
filter coefficients for the modem connection can be downloaded before the modem
connection is set up. With this mechanism implemented in the DuSLIC chip set, the
optimum modem transmission rate can always be achieved.
Figure 35
Figure 35
Initially, the input signal is filtered by a programmable band-pass (center frequency
and bandwidth
(lower path) are determined, and the absolute value is calculated. Both signals are
furthermore filtered by a limiter and a low-pass. All signal samples (absolute values)
below a programmable limit Lev
samples are diminished by Lev
robustness. After the limiter stages both signals are filtered by a fixed low-pass.
The evaluation logic block determines whether a tone interval or silence interval is
detected and an interrupt is generated for the receive or transmit path.
Data Sheet
S
U T D
shows the functional block diagram of the UTD unit:
Universal Tone Detection (UTD) (only DuSLIC-E/-E2/-P)
UTD Functional Block Diagram
f
BW
P rogram m able
). Both the in-band signal (upper path) and the out-of-band signal
B and -pa ss
N
N
. The purpose of this limiter is to increase noise
(Noise Level) are set to zero and all other signal
|x|
|x|
70
Lim it
Lim it
+
+
LP
LP
E v alu ation
Functional Description
Log ic
E Z M 140 61
2000-07-14
DuSLIC
f
C