CXR Larus 80-100-400
Issue 1, July 2006
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5.17 Model 54577 5/10 MHz Output Driver Card
5.1701
This card provides two 5 MHz and two 10 MHz 1 volt peak to peak ±10% sine
wave outputs. An alarm output signal alerts the 54560 Alarm Interface Card
when one or more outputs have failed.
5.171 Functions
5.1711
The Model 54577 5/10 MHz Output Driver Card provides the following:
a. Clock selection based on HOLD indications from the A and B track and
hold cards. The current tracking card or, if both are in HOLD, the last
track and hold card to go into the HOLD state is selected. Switching is
nonrevertive to minimize the number of phase disturbances.
b. Override lines from the 54550 Information Management Card allowing for
manual clock selection and for automatic switching directly to a reference
input in the event that both track and hold cards fail (Major alarm state).
c. Synchronization bus not required. However, when installed in the master
position, the 54577 will generate the synchronization pulse for the bus.
d. One-wire interface to the 54550 Information Management Card to report
personality, alarm, and LED states.
5.172 Circuit
Description
The 54577 block diagram appears in Figure 5-17.
5.1721
Clock Select Switch
The clock select switch is a 1.544 MHz clock selector, LED driver, and output
alarm controller.
5.1722
5/10 MHz Generator
The 5/10 MHz generator produces the 5 MHz and 10 MHz output
frequencies. It also frequency locks the 10 MHz clock outputs to the selected
1.544 MHz input clock. It does this by counting down the 10 MHz VCXO with
6 and 7 fractional frequency synthesis to 1.544 MHz. The two 1.544 MHz
signals are phase locked by the voltage control of the 10 MHz VCXO.
5.1723 Output
Drivers
The output drivers have two lowpass filters to produce 5 MHz and 10 MHz
sine wave signals from square wave input. Each output channel has an
amplifier for driving the output.
