© 2006 Jackson-Labs
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FireFox Synthesizer User Manual
– from F1 to F2 back and forth from F2 to F1 continuously sweeping until the Right key is
pressed. Every sweep from F1 to F2 or F2 to F1 will have a duration D.
The sweep settings are accessible directly from the main menu
SWEEP.
1.4.10 Monitoring the Instrument Status
1.4.10.1 OCXO Status
The FireFox Signal Generator allows its internal status to be monitored via the
STATUS/OCXO
menu
item. The OCXO temperature, the OCXO EFC DAC value, the estimated 30 minute Allan Deviation,
and the GPS pulse number can be monitored when accessing this menu item.
The EFC status shows the value of the present DAC setting from 0% to 100%. This value is typically
between 50% and 60%, and should only change slowly over time.
The
Freq Est
number displayed shows the estimated Allan Deviation for a measurement interval of
30 minutes (1800s). This number is calculated by taking the phase offset measurement between the
GPS 1PPS output, and the internal OCXO 1PPS signal, waiting 30 minutes, then comparing this
value to the present phase offset and calculating the error in one minute updates.
The OCXO temperature shown is measured at the outside of the metal cage of the OCXO, and should
typically be between 45 and 65 Degrees Celsius.
The 1PPS pulse count shows how many 1PPS pulses have been received from the GPS timing
receiver. At least 3600 pulses need to be received for the
Freq Est
to be calculated correctly.
1.4.10.2 GPS Status
The GPS status menu item will display the stored GPS hold-mode position and altitude. The GPS
receiver firmware version can also be checked in this menu item.
The GPS status is also displayed in the LCD main frequency setting menu, on the right hand side
above the “SAT” and “STAT” indicator. The meaning of these indicators is as follows:
LCD STAT indicator
Meaning
OK
The unit is receiving at least one Satellite, and is locked to
better than 15E-011 to UTC
AQ
The unit is searching for Satellites (Acquiring)
AS
The unit is receiving at least 4 Satellites, and is in Auto
Survey mode
2D, 3D
The unit is receiving at least 3 to 4 Satellites, and Position
Hold Mode has been de-selected, or the unit is entering
Auto Survey mode
Table 1-1: GPS Status Indicator Abbreviations
Summary of Contents for FireFox
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