Alcatel 1850 TSS-320 Technical Handbook page 141

3.7.2.1 T0 signal distribution
The T0 system (payload) clock distribution is based on 38.88Mhz signal from each CRG (copy A and copy
B) with an accompanying sync signal (125ms period) providing at least:
– 8khz sync pulse
– A coded counter to derive multi framed sync pulses; each card in the system is in charge of extracting
from it the needed sync pulses, for instance
• 1sec sync pulse synchronizing Performance Monitoring counters
• 2Khz signal aligning LO multi-frames (TU or VT LO frames)
• Clock EPS information
The T0 system (payload) clock and the related sync information are also used to synchronize DCC and
AUX backpanel frames.
A PLL on each I/O port card generates the Tx line clock.
3.7.2.2 T1/T2, T3/T6 and T4/T5 reference signals distribution
Each port that can be source of synchronization, i.e. SDH ports for T1 and PDH ports for T2 references,
can gain access to a 6 wires sync bus that run at 2Mhz for SDH synchronization.
The assignment of the clock extracted from a physical line to a wire of the sync bus is done by provisioning;
functionally the overall provisioning operation is equivalent to a matrix selecting a subset of (up to) 6 SDH/
PDH lines to contribute to T0 and T4/T5 selection processes among all the physical interfaces available
at the NE.
In addition to 6-wires bus for T1/T2, two dedicated point to point connections (Data + Clk) are foreseen
from POW320 A and B to SLCCRU A and B and similarly from SLCCRU A and B to POW320 A and B
for T5/T4 providing external (station) references. These connections can be either 2Mhz (T3) or 2Mhz +
2Mb/s for SDH synchronization (frame termination and SSM extraction done on CRU while LIU is on
POW320)
Furthermore the two CRG copies must be locked in frequency and phase in any operating mode, including
free-running and holdover, to guarantee hitless switch on manual command in any condition. Hence the
signal from local oscillator of each SLCCRU copy is made available to the other copy on a dedicated wires
in addition to standard T1/T2, T3/T6 and T4/T5 connections.
Technical Handbook Common
Functional Description
Alcatel 1850 TSS-320 Rel. 1.1
8DG 07734 AAAA Edition 01 139/270