363-206-295
Circuit Pack Descriptions
7-18
Issue 1
December 1997
General Description of Operation
7
The TG circuit pack provides timing signals to the DDM-2000 OC-12 circuit packs.
The TG circuit pack is microprocessor controlled and has the capability to
synchronize to external DS1 references or to loop references from an incoming
optical signal. The on-board oscillator has sufficient accuracy to provide timing
signals without synchronization references for point-to-point systems (free-
running) and a DS1 timing output for network timing distribution.
The TG circuit pack supports three timing modes to serve a wide range of
DDM-2000 OC-12 synchronization needs: external timing, line (formerly loop)
timing, and free-running. In addition, external timing or line (formerly loop) timing
with DS1 output provisioned for network synchronization is provided.
In external timing mode, each TG circuit pack accepts one DS1 reference from an
external stratum 3 or better clock and one cross-coupled from its companion TG
circuit pack. A high-stability digital phase-locked loop (DPLL) removes any
transient impairments on the DS1 reference for improved jitter performance.
In line (formerly loop) timing mode, the TG circuit pack derives local shelf timing
from the received OC-N signal.
In free-running mode, the TG circuit pack derives timing from a high stability
temperature-compensated, voltage-controlled crystal oscillator.
In case of unprotected synchronization reference failure, the TG circuit pack will
switch to "holdover mode" and continue to provide system timing, using the
internal oscillator to maintain the last known good reference frequency.
DS1 Timing Output
7
The DS1 Output provided by the TG circuit pack can be provisioned to one of two
modes of operation:
■
MULT
— This mode is normally used to distribute a DS1 timing reference to
other shelves in the bay. In this mode, the distributed DS1 Output is
buffered from the external DS1 reference that is input to the shelf.
■
SYNC OUT
— This mode is used to distribute a derived DS1 timing reference to a
BITS. In this mode, the distributed DS1 Output is based on the
timing signal the TG circuit pack has derived from the received
OC-12 signal from the main OLIUs.
— If the DS1 output is provisioned for SYNC OUT mode, DS1 AIS will
be inserted on detection of unprotected OC-N line failure.
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 ...