pef80913 Infineon Technologies Corporation, pef80913 Datasheet - Page 139

• Manufacturer Part Number: pef80913
• Description: 2b1q Second Gen. Modular Isdn Nt
• Manufacturer: Infineon Technologies Corporation

3.2
Test loopbacks are specified by the national PTTs in order to facilitate the location of
defect systems. Four different loopbacks are defined. The position of each loopback is
illustrated in
•
Figure 63
Loopbacks #1, #1A and #2 are controlled by the exchange. Loopback #3 is controlled
locally on the remote side. All four loopback types are transparent. This means all bits
that are looped back will also be passed onwards in the normal manner. Only the data
looped back internally is processed; signals on the receive pins are ignored. The
propagation delay of actually looped B and D channels data must be identical in all
loopbacks.
Besides the remote controlled loopback stimulation via the EOC channel, the Q-
SMINT I features also direct loopback control via its register set.
3.2.1
Loopback #3 is closed by the U-transceiver as near to the U-interface as possible, i.e.
the loop is closed in the analog part by short circuiting the output to the input. The signal
on the line is ignored in this state. For this reason it is also called analog loopback. All
analog signals will still be passed on to the U-interface.
Before an analog loopback is closed by the appropriate C/I-command ARL (activation
request loopback 3), the U-transceiver shall have been reset.
Data Sheet
S-BUS
Layer-1 Controller
Layer-1 Controller
S-Transceiver
Layer 1 Loopbacks
Analog Loopback U-Transceiver (No. 3)
Loop 2
Figure
Test Loopbacks
PBX or TE
IOM
IOM
IOM-2
63.
NT
®
®
-2
-2
U-Transceiver
U-Transceiver
U-Transceiver
Loop 2
Loop 2
Loop 2
Loop 3
U
U-Transceiver
Loop 1 A
125
Repeater
IOM
(optional)
®
-2
U-Transceiver
Operational Description
U
PEF 82912/82913
U-Transceiver
Exchange
Loop 1
loop_2b1q.emf
IOM
2001-03-30
®
-2