Measurements
1780R-Series Operator’s Manual 4–37
Making SCH Phase Measurements
The 1780R-Series offers two methods of measuring SCH phase
errors: The polar SCH display, and this FSC Time Marks (voltage-vs-
time) method. The FSC time marks display is more direct than the
polar display, and affords the operator more manual control, but may
provide a less precise measurement. To ensure an accurate
measurement, both methods can be used.
1. Adjust the waveform monitor controls for a high resolution
display of sync.
2. Adjust the large knob until one of the bright-up dots is at the 50%
point of the leading edge of sync on the waveform display.
3. Push the front-panel REFERENCE SET button. The phase
readout is now 0.00_.
4. Adjust the large knob until the dots are on the zero crossing (or
50% point) of burst on the waveform display.
5. The vectorscope CRT readout now gives SCH phase error in
degrees.
Voltage Cursors in FSC Time Marks Mode
While in Time Marks mode, push the front-panel VOLTAGE
CURSOR button. A voltage cursor menu appears on the right side of
the vectorscope CRT. Touch <ABSOLUTE / RELATIVE> or
<SEPARATE / TRACK> to toggle between those voltage cursor
functions. Refer to the section on Voltage Cursors in Section 3 of this
manual for more details.
Verifying Burst Position
The FSC time marks display can be used to verify that burst is
located 19 subcarrier cycles from the 50% point of the leading edge
of sync.
Position one of the dots on the 50% point of sync, and count the
number of dots between that dot and the dot on the zero crossing of
the first full cycle of burst.
Measurements
1780R-Series Operator’s Manual 4–37
Making SCH Phase Measurements
The 1780R-Series offers two methods of measuring SCH phase
errors: The polar SCH display, and this FSC Time Marks (voltage-vs-
time) method. The FSC time marks display is more direct than the
polar display, and affords the operator more manual control, but may
provide a less precise measurement. To ensure an accurate
measurement, both methods can be used.
1. Adjust the waveform monitor controls for a high resolution
display of sync.
2. Adjust the large knob until one of the bright-up dots is at the 50%
point of the leading edge of sync on the waveform display.
3. Push the front-panel REFERENCE SET button. The phase
readout is now 0.00_.
4. Adjust the large knob until the dots are on the zero crossing (or
50% point) of burst on the waveform display.
5. The vectorscope CRT readout now gives SCH phase error in
degrees.
Voltage Cursors in FSC Time Marks Mode
While in Time Marks mode, push the front-panel VOLTAGE
CURSOR button. A voltage cursor menu appears on the right side of
the vectorscope CRT. Touch <ABSOLUTE / RELATIVE> or
<SEPARATE / TRACK> to toggle between those voltage cursor
functions. Refer to the section on Voltage Cursors in Section 3 of this
manual for more details.
Verifying Burst Position
The FSC time marks display can be used to verify that burst is
located 19 subcarrier cycles from the 50% point of the leading edge
of sync.
Position one of the dots on the 50% point of sync, and count the
number of dots between that dot and the dot on the zero crossing of
the first full cycle of burst.