Nautel NX15, Operation And Maintenance Manual

Page: 122 / 178

NX15/NX25 Operations and Maintenance Manual Operating the transmitter
Page 2-98 Issue 6.0 2019-01-31
Exciter Clock Calibration
The
Exciter Clock Calibration
page (see Figure 2.71 ) allows you to calibrate the internal clock
reference to an external 10 MHz clock by pressing the
Calibrate
button. Both exciters are
calibrated at the same time. Note: typically, a value change is not required.
The exciter clock may also be synchronized to a reference source, either an external 10 MHz
reference connected to A11A1J8 or a Nautel optional GPS sync PWB
,
or a combiner, as
applicable. The Combiner source option is applicable for combined systems only. The exciter
reference will lock to the external source frequency within 10 mHz (0.01 Hz) using the
10 MHz sync input, to within 2 mHz (0.002 Hz) using the GPS sync card without an antenna,
and to within the quality of the GPS system when using the GPS sync card with an antenna.
Figure 2.71: System Settings - Exciter Clock Calibration
Procedure to calibrate the exciter clock:
1. Select the
Exciter Clock Calibration
option from the left side of the
System Settings
page to open a related window on the right side of the page.
2. Connect an external 10 MHz source to A11A1J8, verify a value near 10 MHz displays
in both
External Clock Frequency
fields, and press
Calibrate.
If None (default) or 10MHz Sync Source is selected, no other settings are required.
If GPS Sync Card is selected, the Antenna Present drop-down field is also displayed (select Yes or No)
If Combiner is selected (for combined systems only), the Phase Offset field is also displayed.