PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 67

• Manufacturer Part Number: PEF2091
• Description: ICs for Communications(ISDN Echocancellation Circuit)
• Manufacturer: Siemens Semiconductor Group

3.5
The IEC-Q interfaces with the metallic line through this block. Both are linked by an
external circuitry consisting of a transformer and a hybrid circuitry (refer to Figure 93,
page 250 for details).
3.5.1
The output stage comes out of two identical buffers operating in differential mode. This
concept allows an output swing of 6.4 Vpp between the output pins AOUT and BOUT of
the IEC-Q. The nominal peak values of
2.5 V
The input signal from the metallic line is detected on the differential inputs AIN and BIN.
The swing of the input signal measured must be below 4 Vpp.
3.5.2
Transmission on the U-interface is performed at a rate of 80 kBaud. The code used is
reducing two binary informations to one quaternary symbol (2B1Q).
Data is grouped together into U-superframes of 12 ms each. The beginning of a new
superframe is marked with an inverted synchronization word (ISW). Each superframe
consists of eight basic frames which begin with a standard synchronization word (SW)
and contain 222 bits of information. The structure of one U-superframe is illustrated in
Figure 21, and 22. For a detailed description of one complete superframe see Table 10,
page 68.
Figure 21
Figure 22
Out of the 222 information bits 216 contain 2B + D user data, the remaining 6 bits are
used to transmit maintenance bits. Thus 48 maintenance bits are available per
U-superframe. They are used to transmit two EOC-messages (24 bit), 12 overhead bits
and one check sum (12 bit).
Semiconductor Group
ISW
<---12 ms--->
(I) SW
(Inverted) Synch Word
18 Bit (9 Quat)
<---1,5 ms--->
peak
1. Basic Frame
on the metallic line.
U-Interface
Output and Input Signals
U -Frame Structure
U-Superframe Structure
U-Basic Frame Structure
SW
12
User Data
216 Bits (108 Quat)
2. Basic Frame
2B + D
3 correspond to a 3.2 V
67
. . .
M1 – M6
Maintenance Data
6 Bits (3 Quat)
SW
Functional Description
peak
8. Basic Frame
chip output and
Data Sheet 01.99
PEB 2091
PEF 2091