12778474-002-2 Revision F – March 2004
TSG-3800 User’s Guide 179
CPU, Frame Generator, and Clock Modules
Clock Module
The Clock module front panel contains status indicators.
Table 6-6
describes the
front panel Clock module status indicators.
Functional Description
The Clock Output module consists of the following five sections, as shown in
Figure
6-5
:
Oscillator
Direct Digital Synthesizer (DDS)
Timing Circuitry
Module Control
The Oscillator provides a 10 MHz sinusoidal output signal for the DDS circuitry. The
type of oscillator varies depending on the Clock module. It may be a Rubidium
oscillator for the highest quality Stratum 2 performance, or various Quartz ovenized
oscillators for the lower quality levels. The output signal is buffered to provide a 10
MHz logic signal as a clock to the DDS circuitry. A separately buffered signal is
provided to the local oscillator (LO) output jacks on the rear panel of the main shelf
for connecting to external equipment such as a GPS receiver.
Table 6-6. Clock Output Module Indicators
Indicator
Color
Description
POWER
Green
On = The module is receiving power
LOCKED
Green
On = Unit is in Normal mode of operation
SELECTED
Green
On = Module selected for providing outputs
EXT REF
Green
This indicator not used
HOLDOVER
Amber
On = Unit is in Holdover mode of operation
END OF RANGE
Amber
On = Tuning is below 25% or above 75% of full scale
ACQUIRE
Amber
On = Unit is in Acquire mode of operation
FAULT
Red
On = Fault within the Module
Blinking = Module is disabled
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