Nortel Circuit Card 311 Reference page 917

To prevent chatter due to repeated automatic switching between primary
and secondary reference sources, a time-out mechanism of at least 10
seconds is implemented.
Digital to analog converter
The Digital to Analog Converter (DAC) enables the microprocessor to track,
hold, and modify the error signal generated in the digital PLL.
The firmware uses the available memory on the clock controller to provide
error-burst detection and correction. Temporary holdover occurs in the
momentary absence of the reference clock.
The DAC (digital to analog converter) allows the microprocessor to track,
hold, and modify the error signal generated in the digital PLL.
The firmware uses the available memory on board the clock controller to
provide error-burst detection and correction. Temporary holdover occurs in
the momentary absence of the reference clock.
The Digital to Analog Converter (DAC) enables the microprocessor to track,
hold, and modify the error signal generated in the digital PLL.
The firmware uses the available memory on the clock controller to provide
error-burst detection and correction. Temporary holdover occurs in the
momentary absence of the reference clock.
Holdover and free-run
In the temporary absence of a synchronization reference signal, or when
sudden changes occur on the incoming reference due to error bursts, the
clock controller provides a stable holdover. Free-run mode is initiated when
the clock controller has no record of the quality of the incoming reference
clock.
If the command "free run" is given, the clock controller enters the free-run
mode and remains there until a new command is received. Free-run
automatically initiates after the clock controller has been enabled.
In the temporary absence of a synchronization reference signal, or when
sudden changes occur on the incoming reference due to error bursts, the
clock controller provides a stable holdover. The free-run mode is initiated
when the clock controller has no record of the quality of the incoming
reference clock
Copyright © 2003-2008, Nortel Networks
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Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
Functional description 917