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TimeHub 5500 User’s Guide
097-55501-01 Revision M – January 2009
Chapter 1 Description
Expansion Shelf
Expansion Shelf
For situations requiring more outputs than can be provided by a Master shelf, the
TimeHub 5500 supports one to four Expansion shelves. Each Expansion shelf
provides up to 320 protected outputs; using four Expansion shelves, a TimeHub
5500 system can provide a total of 1420 outputs.
illustrates the Expansion shelf. Several types of plug-in cards are used in
the front panel of the Expansion shelf: DS1/CC Driver cards (090-55581-01),
Expansion Controller cards (090-55545-01), 5 MHz Output cards (p/n
090-55583-01) and NTP Server cards (090-55582-01). Output Connector modules
installed on the rear panel provide DS1, CC, or 5 MHz outputs; an NTP Output
Connector module (090-55594-02) is available for the Expansion shelf.
Table 1-2. SSM Source Determination for Remote Shelf
Condition
SSM Source
Shelf has no active timing reference (“A” is not
lit in either CC1 or CC2 row).
The SSM value is that of the internal oscillator in
the active Clock card (see HFQLEVL keyword in
the
TL1 Reference Guide
).
Shelf has at least one active timing reference
("A" is lit in either CC1 or CC2 row).
The SSM value is taken from the “assumed” SSM
value (see QLEVEL keyword in the
TL1 Reference
Guide
) associated with the active timing reference.
For example, if CC2 is the active timing reference,
the SSM is taken from QLEVEL setting for channel
11 (Channel 11 is the TL1 reference to CC2).
There are no valid SSM inputs. (No signal/or
non-decodable signal connected to DS1-1 and
DS1-2) OR neither SSM input is enabled ("E"
LED not lit in both DS1-1 and DS1-2 rows).
Shelf has at least one active timing reference
("A" is lit in either CC1 or CC2 row)
The SSM value is being decoded from the DS1
input that is showing “E”, “Q”, and “A”.
There is a single valid SSM input (“E”, “Q”,
and “A” lit on one DS1 input, Q is not lit on the
other one)
Shelf has at least one active timing reference
("A" is lit in either CC1 or CC2 row)
The SSM value is taken from the DS1 input that
has the higher PRIORITY (lower numerical value)
setting. This is the one that has “A” lit. See the
TL1
Reference Guide
for details on PRIORITY
keyword.
Both DS1-1 and DS1-2 are decoding valid
SSM information ("E" and "Q" are lit for both
DS1-1 and DS1-2 rows). Only one of these
rows can indicate "A".
Note:
In order to support Expansion shelves, the Master shelf must
be equipped with Extended-Capacity Clock cards, as described in
, on page 29. Standard Clock cards do not support
Expansion shelves.