Tektronix SPG8000A, User Manual

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SPG8000A User Manual 77
To enable GPS or PTP
and CW reference
To use this function, access the CW frame menu and set the CW frame to
Keep
GPS/PTP Timing
. The CW frame menu operation is displayed in the REF button
menu section.
Set the reference to GPS or PTP and allow the system to lock. Connect the CW
input and then switch to CW reference. There may be a small shift as this locks, so
it should be done at a noncritical time. To relock to the GPS or PTP, change the
reference back to that source. Depending on how long the system has been
drifting, this will cause more of a disruption, so it should be done at a noncritical
time. The SPG8000A should be configured to power on in the GPS or PTP mode
so it recovers the time and phase correctly. A second SPG8000A can be locked to
the GPS or PTP, and outputs from the main and extra SPG can be compared in a
monitor to help determine how much the system has drifted, and when it is a good
time to relock to the GPS or PTP.
Genlock Timing Settings
The Genlock Timing settings adjust the timing offset of the input signal relative to
the internal reference signal. The selections are unavailable when the reference
source is set to Internal or GPS Signal.
The range of the timing adjustment depends on the selected signal format. (See
Table 24 .)
•
Vertical Delay . Enter the delay to adjust the Genlock vertical offset in
1- line increments.
•
Horizontal Delay
. Enter the Genlock horizontal offset.
Note:
If you are using the 50, 59.94 or 60 Hz progressive sync as a genlock source
and LTC as a time - code source, there are two possible alignments for the resulting
system. Alignment can be checked by looking at the LTC timing status screen. If
the timing is near zero, then it is aligned. If the timing is near a frame of offset,
then it is not aligned.
You must unlock and relock the reference to obtain the needed alignment if this is
important to the application you are using. Alternatively, you can use a lower
frame rate video reference like NTSC, PAL, or 1080i tri- level.
Table 24: Timing adjustment ranges for reference input signals
Format name Line settings Coarse settings (μs) Fine settings (ns)
NTSC ± 525 ± 63.5556 ± 10.00
PAL ± 1250 ± 64.0000 ± 10.00
1080 60i ± 562 ± 29.6296 ± 10.00
1080 59.94i ± 562 ± 29.6593 ± 10.00
1080 50i ± 562 ± 35.5556 ± 10.00
1080 24sF ± 562 ± 37.0370 ± 10.00
1080 23.98sF ± 562 ± 37.0741 ± 10.00
1080 30p ± 562 ± 29.6296 ± 10.00