097-10603-01 Rev. A – November 2004 X72 Desiger’s Reference and User’s Guide 37
Design Integration Considerations
Electrical Interface
If the LOCK signal is high, atomic lock has been lost and the X72 goes into sweep
mode to reacquire lock. The sweep ranges from approximately –21 ppm to +21 ppm
in approximately a 20 second period. During the sweep, outputs are maintained but
you should not rely on signal accuracy during sweeping. If the power source to the
X72 is OFF, the lock output line is low.
Service Signal
The Service Signal is valid when the unit is operating and the rubidium oscillator is
locked.
The Service Signal algorithm monitors the health of the Rb physics package, which
includes the Rb lamp bulb and resonator cell, and the unit’s crystal oscillator that is
slaved to the Rb atomic clock.
The Service Signal indicates low when any of the internal operating parameters are
near the end of their tuning or adjustment range, providing a month’s warning of this
situation.
X72 Frequency Control Signal
The X72 frequency control signal is an analog input between 0 and 5 Vdc that can
be enabled or disabled at the factory (making it a default setting) or by the customer
at a later date (using the SSIP). The Service BIT can be selectable high or low.
When in use, the smallest incremental frequency change is 2xE
–12
(or f.2). The unit
always powers up to the preset free running factory set frequency. Adjustments to
the frequency are always relative to the free running frequency of the unit (see also
Frequency Control Analog, on page 38).
X72 ACMOS Output Frequency
The ACMOS output frequency is equal to the crystal frequency divided by 2N (N is a
number from 1 to 65536). For example, the SSIP command to modify the output of
the VCXO for an output of 10 MHz from a 60 MHz XO is “o3”.
To Next Page
Loading...
Need help?
General
