psb21391 Infineon Technologies Corporation, psb21391 Datasheet - Page 72

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

Data Sheet
2.3
The layer-1 functions for the U
– conversion of the frame structure between IOM and U
– conversion from/to binary to/from half-bauded AMI coding
– level detection
– receive timing recovery
– IOM-2 timing synchronous to U
– D channel access control
– activation/deactivation procedures, triggered by primitives received over the IOM C/I
– execution of test loops
2.3.1
Figure 37 demonstrates the general principles of the U
scheme. A frame transmitted by the exchange (LT) is received by the terminal equipment
(TE) after a line propagation delay. The terminal equipment waits the minimum guard
time (t
exchange will begin a transmission every 250 s (known as the burst repetition period).
Within a burst, the data rate is 384 kbit/s and the 38-bit frame structure is as shown in
figure 37. The framing bit (LF) is always logical ‘1’. The frame also contains the user
channels (2B + D). Note that the B-channels are scrambled. It can readily be seen that
in the 250- s burst repetition period, 4 D-bits, 16 B1-bits and 16 B2-bits are transferred
in each direction. This gives an effective full duplex data rate of 16 kbit/s for the
D-channel and 64 kbit/s for each B-channel. The final bit of the frame is called the M-bit.
Four successive M-bits, from four successive U
figure 37). Three signals are carried in this superframe. The superframe is started by a
code violation (CV). From this reference, bit 3 of the superframe is the service channel
bit (S). The S-channel bit is transmitted once in each direction in every fourth burst
repetition period. Hence the duplex S-channel has a data rate of 1 kbit/s. It conveys test
loop control information from the LT to the TE and reports transmission errors from the
TE to the LT. Bit 2 and bit 4 of the superframe are the T-bits. In order to decrease DC-
offset voltage on the line after transmission of a CV in the M-bit position, it is allowed to
add a DC-balancing bit to the burst. The LT-side transmits this DC-balancing bit, when
transmitting INFO 4 and when line characteristics indicate potential decrease in
performance.
Note that the guard time in TE is always defined with respect to the M-bit, whereas AMI-
coding includes always all bits going in the same direction.
The coding technique used on the U
50 % pulse width). A logical ‘0’ corresponds to a neutral level, a logical ‘1’ is coded as
alternate positive and negative pulses.
channel or by INFO's received from the line
g
= 5.2 s) while the line clears. It then transmits a frame to the exchange. The
U
U
PN
PN
Interface
Burst Frame
PN
interface of the SCOUT-P(X) are:
PN
PN
interface is half-bauded AMI-code (i.e. with a
62
PN
frames, constitute a superframe (see
PN
PN
interface
interface communication
PSB 21391
PSB 21393
Interfaces
2001-03-07