Rev G REF TEK 130 Multi-Channel Users Guide 5/14/2021
96223-00-UG
30 Reftek Systems Inc.
General GPS operations
When the host 130-MC receives power it:
1. Supplies +12 VDC to the GPS clock.
2. Issues a reset to the 130-GPS/01.
Once the GPS has locked (per GPRMC-valid bit) the 130-MC:
1. Compares its time to GPS UTC time.
2. Begins phase locking for 30 seconds.
3. Uses the 1 Hz from the 130-GPS/01 to start and stop a counter to record the internal high-precision
oscillator.
4. Uses the difference between the value from the 1st second and the value from the 30th second to
determine the rate of drift of the oscillator.
5. The 30th value is also used to determine the phase error of the internal 1 Hz.
6. The oscillator is voltage-controlled and an adjustment is made to the controlling D/A value to zero
out the oscillator drift, and also to correct for oscillator phase error.
At initial power-up the 130-MC will leave the GPS on for approximately 15 minutes to do
continuous phase-locking and oscillator adjustment.
In Cycled mode the 130-MC:
1. Power down the GPS.
2. Awakens the GPS and repeats the above phase locking algorithm each hour at 40 minutes after the
hour.
In Continuous mode the 130-MC:
1. Leaves the GPS powered on continuously.
In OFF mode the 130-MC:
1. Powers down the GPS.
2. Does not turn the GPS power back on.
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