Spectracom 8194B, Инструкция по эксплуатации

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Spectracom Corporation 8194B, 8195B, 8197B
GPS Ageless Master Oscillator Instruction Manual
6-3
NOTE:
The next two sections only apply to Models 8194B and 8195B that use an
OCXO 10 MHz oscillator. It does not apply to the Model 8197B that has a
Rubidium oscillator. For Rubidium oscillator adjustment, you will need to send
the unit back to Spectracom’s technical support department.
6.3 OCXO Oscillator Adjustment (8194B and 8195B ONLY)
Over time the OCXO 10 MHz oscillator may require an adjustment to compensate for
crystal aging. The unit warns when this adjustment is needed by asserting an Adjust
Oscillator Alarm. This condition activates the Minor Alarm status lamp and relay. An
Adjust Oscillator Alarm is asserted when the frequency controlling D/A converter
approaches a control range limit. Typically, this alarm provides a two to three month
warning before a control range end is reached.
On rare occasions, an oscillator may experience a sudden shift in frequency, causing an
Adjust Oscillator and a Frequency Alarm. When this occurs, both Major and Minor
alarms are activated. The D/A is set to a control range end unable to correct the
oscillator frequency. Frequency error shall exceed 1 x 10
-8
This section describes the oscillator adjustment procedure using a frequency counter
and an RS-232 terminal. After completing the adjustment procedure, the alarm lamps
and relays are cleared, and the oscillator will reacquire phase lock to the GPS
reference.
The frequency counter must have a time base accuracy and measurement resolution of
at least 1 x 10
-9
(0.01 Hz at 10 MHz).
A PC running terminal emulation software (HyperTerminal, ProComm Plus, etc.) can be
used as an RS-232 terminal. Configure the terminal for ANSI emulation, 9600 baud and
a character structure of 1 start, 8 data, 1 stop and no parity. Flow control is not
required, although xon/xoff is supported.