097-10603-01 Rev. A – November 2004 X72 Desiger’s Reference and User’s Guide 45
Installation and Operation
Start-up Sequence
Once the X72 is plugged in and is receiving power, wait 3 to 4 minutes while the unit
achieves atomic lock. During this period, the monitored LOCK signal should be
HIGH. Once the unit achieves atomic lock, the LOCK signal goes LOW.
Depending on base plate temperature, within 4 to 8 minutes the unit should be
within 1xE
–9
of center frequency. Thirty minutes after applying power to the X72 the
rf output frequency will be very close to full accuracy (refer to X72 specifications).
Start-up Sequence
When power is connected to connector J1, the X72 begins its warm-up cycle. After
four minutes the rubidium oscillator reaches a locked condition and its output
signals will stabilize. The accuracy at shipment is <±5xE
–11
at 25° C, typical.
After 7.5 minutes the accuracy of the X72 oscillator is <1xE
–9
. Performance of the
X72 unit varies according to the application profile specified by the customer at time
of order. Refer to the X72 product specification for information on application
profiles and unit performance.
To monitor performance and selectively modify it using the SSIP firmware included
in the unit, connect the unit to the COM port of a PC running Windows.
Note: The output frequency of the X72 is more accurate than most
counters. Appropriate measurement equipment can be obtained from
Symmetricom. Inquire with Symmetricom Marketing, or your local
sales representative, about Symmetricom’s line of test and
measurement standards, which includes the PRFS and FMS-2001.
Note: Signals appear at the outputs immediately after power is
applied to the unit, but these output signals are not stable until after
the oscillator has locked.
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