Transmission Interface Handling G.703 2048 kbit/s
−
ERATE (Error RATE)
−
AIS (Alarm Indication Signal)
−
RAI (Remote Alarm Indication)
The consequent actions are transmission of:
•
Alarm indication to the remote end (A-bit in time slot 0 equal to
"1")
•
CRC-4 error indicator (E-bit in time slot 0 equal to "0")
Both actions are according to ITU-T recommendations G.704 and G.732.
•
Transmission of spare bits (Sa4-Sa8). The spare bits form a fixed
bit pattern (see section Section 32.4.1 Operation and Maintenance
on page 197)
Two PCM paths are supported: PCM-A and PCM-B. However, PCM-B
can only be used when the function Multidrop (see chapter Channel
Distribution Function) is activated.
32.3.2
Layer 1 Termination Long Haul 2048 kbit/s, 120 Ohm
The function is initiated during restart of CMRU.
The function is handled according to Section 32.3.1 on page 189 except
for the receiver sensitivity and cable type.
The receiver dynamic range is 0 to -30 dB at 1024 kHz (0 dB = 6.0
Vp-p, 120 ohms twisted pair cables).
32.3.3
Layer 1 Synchronization
Synchronization of layer 1 is either derived from PCM A or taken from
a free running oscillator. If PCM-A is in one of the alarm states
•
LOF (Loss Of Frame), or
•
LOS (Loss Of Signal)
•
AIS (Alarm Indication Signal)
it cannot be used as reference source.
The synchronization of layer 1 is in one of two states:
1.
PCM-A can be used as reference source
PCM-A is selected as the reference source
PCM-A incoming is used to synchronize PCM-A outgoing
PCM-A incoming is used to synchronize PCM-B outgoing.
2.
PCM-A cannot be used as reference source
The free running oscillator is selected as reference source
The free running oscillator is used to synchronize both PCM-A
and B outgoing.
190 (306)
EN/LZT 123 2697
R5A
1998-08-13
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