363-206-295
Circuit Pack Descriptions
Issue 1
December 1997
7-21
Clock Output Functions
7
Intra-shelf Timing Distribution.
7
The generated timing signals are distributed
through output drivers to the main and function unit slots. The TG circuit pack
provides eight differential 51.84-MHz master clock signals and eight differential
8-kHz composite STS-1 frame sync signals. In the 8-kHz sync signal, every fourth
pulse is stretched to double width, providing an embedded 2-kHz reference for the
virtual tributary (VT) superframe synchronization.
DS1 Outputs .
7
The DS1 output port can be provisioned by hardware switches for
MULT mode or DS1 timing synchronization (SYNC OUT) mode.
■
SYNC OUT Mode
— The DS1 output port of the BBF2B TGS circuit pack can be
provisioned to be a derived DS1 signal traceable to a received
optical line used for network timing distribution. The SYNC OUT
capability is available for a DDM-2000 set for external-timing or line-
timing.
■
MULT Mode
— The DS1 output port of the TGS circuit pack can be provisioned to
output a buffered copy (at a DSX level) of the DS1 signal at the input
port. A DS1 traceable source is applied to the first DDM-2000 shelf.
The output of the first shelf is then cabled to the second shelf, and
all subsequent shelves fed from the previous ones. In this way, a
MULT chain is formed from a single DS1 reference. The MULT
capability is only available for a DDM-2000 provisioned for external-
timing.
Protection Circuitry
7
In both external and line (formerly loop)-timing modes, the synchronization
references are continuously monitored for error-free operation. If the active
reference becomes corrupted, the TG circuit pack will select the standby
reference without causing service degradations (that is, hitless reference
switching). If both reference inputs are corrupted, the TG circuit pack enters
holdover mode where the DPLL holds the on-board oscillator frequency at the last
good reference sample while the references are repaired.
In addition, optional 1x1 nonrevertive TG circuit pack protection is provided. When
the active TG circuit pack microcontroller determines that its clock output is out of
tolerance, it suppresses its timing outputs and signals its TG circuit pack
companion unit of its failed condition. The suppressed timing outputs cause a
timing hardware switch to the standby TG circuit pack by the transmission circuit
packs.
Содержание DDM-2000 OC-12
Страница 1: ...363 206 295 Issue 1 December 1997 DDM 2000 OC 12 Multiplexer Release 7 0 User Service Manual Volume I ...
Страница 37: ...Tables xxxviii Issue 1 December 1997 A A SONET Overview A 1 SONET Payloads A 18 A 2 SONET Transport Rates A 19 ...
Страница 506: ...INS PROG 8 of 8 Page INS PROG COMMANDS RELATED rtrv eqpt rtrv ne OC 12 DDM 2000 1997 December 1 Issue 11 89 ...
Страница 528: ...RTRV ATTR ALM 2 of 2 Page RTRV ATTR ALM COMMANDS RELATED set attr alm OC 12 DDM 2000 1997 December 1 Issue 11 111 ...
Страница 565: ...RTRV OC3 3 of 3 Page RTRV OC3 COMMANDS RELATED rtrv sync 11 148 1997 December 1 Issue OC 12 DDM 2000 ...
Страница 664: ...SET FEAT 3 of 3 Page SET FEAT COMMANDS RELATED rtrv feat OC 12 DDM 2000 1997 December 1 Issue 11 247 ...
Страница 766: ... Ctl T TOGGLE 2 of 2 Page Ctl T TOGGLE COMMANDS RELATED logout rlgn OC 12 DDM 2000 1997 December 1 Issue 11 349 ...
Страница 847: ...Multiplexer OC 12 DDM 2000 7 Release TARP TOP Manual User Service II Volume 363 206 295 1 Issue 1997 December ...
Страница 867: ...363 206 295 TOP Maintenance and Operation BLANK LEFT INTENTIONALLY PAGE THIS 12 1997 December 1 Issue ...
Страница 1145: ...Order Circuit 363 206 295 NTP 029 1 of 1 Page 1997 December 1 Issue Unused LISTED ORDER IN BELOW ITEMS DO TO GO DETAILS FOR ...
Страница 1146: ...Order Circuit 363 206 295 NTP 030 1 of 1 Page 1997 December 1 Issue Unused LISTED ORDER IN BELOW ITEMS DO TO GO DETAILS FOR ...
Страница 1182: ...Turnup System 363 206 295 NTP 033 1 of 1 Page 1997 December 1 Issue Unused LISTED ORDER IN BELOW ITEMS DO TO GO DETAILS FOR ...
Страница 1243: ...Clearing Trouble 363 206 295 TAP 107 1 of 1 Page 1997 December 1 Issue Unused ...
Страница 1393: ...363 206 295 DLP 513 1 of 1 Page 1997 December 1 Issue Unused ...
Страница 1394: ...363 206 295 DLP 514 1 of 1 Page 1997 December 1 Issue Unused ...
Страница 1456: ...363 206 295 DLP 523 7 of 7 Page 1997 December 1 Issue OC 12 via Access Broadcast Video for Cross connections of Example 4 Figure ...
Страница 1465: ...DLP 525 363 206 295 1997 December 1 Issue 6 of 2 Page Schematic Ring Virtual ATM Sample 1 Figure ...
Страница 1469: ...DLP 525 363 206 295 1997 December 1 Issue 6 of 6 Page Ring Virtual ATM OC 12 DDM 2000 for Cross connections of Example 4 Figure ...
Страница 1565: ...363 206 295 DLP 543 6 of 5 Page 1997 December 1 Issue Network Broadcast Video of Test Transmission 2 Figure ...
Страница 1566: ...DLP 543 363 206 295 1997 December 1 Issue 6 of 6 Page Network Ring Virtual ATM of Test Transmission 3 Figure ...