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•
VCXO:
On the unit is present a VCXO supplying a 125MHz clock to all the logics processing the
Ethernet signal.
–
SDH termination:
•
SWITCH: The task of the SWITCH block is to send the signals coming from HPT or LPT block
towards the matrix on the MATRIX board. The selection is made according to the type of signal
to be connected (L if it is structured, X if unstructured). The "L" signals are sent to LPT – LPA
blocks, the "X" to the HPT.
•
HPT: this block adds/removes the high order POH bytes to the C–4 unstructured payloads
(bulks).
•
LPT: The LPT function terminates a VC–12 or a VC–3 by adding or removing the relevant POH
bytes to a C–12 or a C–3.
•
LPA: This block adapts the low order payloads C12 or C3 to the higher order containers used
for transportation in the SDH (TU–12 or TU–3). The adaptation includes timing synchronization
and frame offset with pointers movements.
•
Struct/Unstr: this selector sends the bulk signals (unstructured) to HPT, while the structured
signals are sent to LPA–LPT.
–
Other functions implemented on the board are:
•
RIBUS I/F
This block is used to read/write from/to the "RIBUS" serial stream, to control the LED on the unit,
to release the Management–bus in case of power failure, and to use the remote inventory.
RIBUS I/F is powered by the + 3.3 VS supplied by the CONGI
•
REMOTE INVENTORY
It is the memory containing the board information, for identification purposes (see para. 3.17
on page 370 for details about Remote Inventory information).
•
M–BUS Driver
It drives the input–output gates of the serial Management–bus. These drivers can be disabled
(by the Bus–OFF signal) in case of power failure.
•
DC/DC CONVERTERS
This block converts the 48/60 V power supply, to obtain the voltages used to supply all the
components in the board.
The DC/DC converter is synchronized with a synchronization clock at 300 MHz (signal
Power–Sync, generated by the SDH asic) in order to avoid EMI problems.
•
LEDS
The board presents on its front panel one LED the meaning of which is reported in Figure 44.
on page 134.
•
Buses
The main buses on the board are:
ISSB–EC: serial bus from the EC, to communicate software data (download, etc.).
SDH–CS: from the EC, after derivation from the serial "Management–bus", for configuration
and status information of SDH components.
RIBUS: serial bus from the SC (shelf controller on MATRIX unit), to communicate inventory and
peripheral data.
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