OPERATION
Note: If you have just installed revised/upgraded firmware or performed a “Cold Reset” (see
Chapter Five), an additional extra screen will be displayed in front of your Main Menu
Screen. This screen will only appear the first time power is applied to your unit after a
Cold Reset or the new firmware has been installed. After that, the normal Main Menu
Screen will appear. This additional Initial Calibration screen is shown below:
Column:
Row 1
Row 2
This internal, automatic
Time Interval Calibration is necessary to get accurate nanosecond time interval resolution for the
measurement of the GPS and external 1PPS. In the example above, 142 and 123 are the current
values, 195 and 157 are the high values, 073 and 056 are the low values, and 198 is the number
of seconds remaining until the calibration is finished. This number starts at 250 and decrements
to zero at a one second rate.
1 5 10 15 20 25 30 35 40
| | | | | | | | |
000.00:00:12 < DOING TIME INT. CALIB. >
142 195 073 123 157 056 198
If the MENU key is pressed prior to completing the calibration process, the calibration will be
interrupted and the process aborted. However, an additional menu screen (this Time Interval
Calibration MENU) will be enabled. The user can access this screen if he cycles through the
various menus by pushing the MENU key. This Calibration Menu screen will enable the
nanosecond time interval calibration to be completed at a later date.
It is important to note that if this automatic time interval calibration is interrupted prior to
its completion, it will be necessary to restart and complete it (using the TIME INTERVAL
CALIBRATION MENU screen) or inaccurate time interval measurements will result.
The following is the normal MAIN MENU that is displayed. It contains the following
information:
Symmetricom Firmware Version.
Synchronization.
Time (Seconds through Days).
Status and Error Messages.
Frequency Offset.
Satellite PRN Identification.
Mode.
Symmetricom Inc ET6xxx ExacTime GPS TC & FG (Rev C) 3-5
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