363-206-295
Transmission and Synchronization Interfaces
5-10
Issue 1
December 1997
Synchronization Interfaces
5
Each DDM-2000 OC-12 Multiplexer can be provisioned to one of three timing modes:
■
Free-running from an internal oscillator
■
Line timing from an incoming optical interface. This timing reference is used to
generate all outgoing signals. Line timing is an intermediate node that derives
timing from the incoming fiber. Loop timing is a special case of line-timing and
is the terminating node that derives timing from the incoming fiber.
■
External timing from the digital synchronization network via DS1 references
(DS1 External).
The terms loop timing and line-timing have been changed to clarify timing
terminology. When the OLIU derives local shelf timing from the incoming
optical signal and the shelf is an intermediate shelf (choice of OC-N lines for
timing) in a linear network for example, it is called line-timing. Loop timing is a
subset of line-timing used to describe the timing mode of the terminating node
(single source of timing) of a linear network, for example.
NOTE:
The synchronization and timing examples used throughout this chapter
reference the timing generators as “TG.” This could represent either the BBF2B
TGS or the stratum 3 BBF4 TG3.
Free-Running
5
For free-running operation, the TG derives timing from a temperature-compensated,
voltage-controlled crystal oscillator (TCVCXO) and a digital phase-locked loop
(DPLL) with a full temperature range end-of-life accuracy of
±
15 parts-per-million
(ppm) for the BBF2B TGS, and
±
4.6 ppm for the BBF4 TG3.
Line Timing
5
The reference signal feeding the phase-locked loop (PLL) is selected from the
internal oscillator or a line-timing clock derived from the incoming optical line. In line-
timing mode, the OC-12 line being selected for transmission is also selected as the
timing reference.
DS1 External
5
Each TG circuit pack receives one DS1 reference signal which it monitors and from
which it recovers a clock signal. The recovered clock is cross-fed to its companion TG
circuit pack in the same shelf. If the microprocessor on one TG circuit pack detects an
incoming DS1 reference failure, it will signal the microprocessor on the companion
TG circuit pack.
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 ...