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Measurements
1780R-Series Operator’s Manual
4–11
6. Differential gain is the amount of signal that is above or below
the graticule reference mark. Read the amount directly off the
graticule scale (waveform CRT); 1 major division = 1% (10 IRE
NTSC or 100 mV PAL).
Double-Trace DIFF GAIN Measurement Procedure
1. Apply a staircase signal or a ramp signal with subcarrier to the
1780R-Series.
2. Touch <DOUBLE>.
3. Use the vectorscope variable gain control to set the amplitude of
the chroma to be measured to the compass rose.
4. Locate the point of largest deviation between the two traces
(waveform CRT), and use the large knob to bring the traces
together at this point.
5. Push the REFERENCE SET front-panel button. Diff gain readout
should be 0.0%.
6. Locate the point of largest deviation between the two traces, and
use the large knob to bring the traces together at this point.
7. Diff gain readout (waveform CRT) now gives the total amount of
differential gain.
8. To measure the differential phase of each step in the signal,
repeat the process, bringing each individual step together.
Using Line Select in DIFF GAIN
1. Push the front-panel LINE SELECT button to enable Line Select
mode. Both the waveform monitor and vectorscope will be in
Line Select, and display the same line.
2. Line Select readout is provided on the waveform CRT.
3. Touch <MENU> to outline <ON> for Line Select menu display
on the vectorscope CRT.
Measurements
1780R-Series Operator’s Manual
4–11
6. Differential gain is the amount of signal that is above or below
the graticule reference mark. Read the amount directly off the
graticule scale (waveform CRT); 1 major division = 1% (10 IRE
NTSC or 100 mV PAL).
Double-Trace DIFF GAIN Measurement Procedure
1. Apply a staircase signal or a ramp signal with subcarrier to the
1780R-Series.
2. Touch <DOUBLE>.
3. Use the vectorscope variable gain control to set the amplitude of
the chroma to be measured to the compass rose.
4. Locate the point of largest deviation between the two traces
(waveform CRT), and use the large knob to bring the traces
together at this point.
5. Push the REFERENCE SET front-panel button. Diff gain readout
should be 0.0%.
6. Locate the point of largest deviation between the two traces, and
use the large knob to bring the traces together at this point.
7. Diff gain readout (waveform CRT) now gives the total amount of
differential gain.
8. To measure the differential phase of each step in the signal,
repeat the process, bringing each individual step together.
Using Line Select in DIFF GAIN
1. Push the front-panel LINE SELECT button to enable Line Select
mode. Both the waveform monitor and vectorscope will be in
Line Select, and display the same line.
2. Line Select readout is provided on the waveform CRT.
3. Touch <MENU> to outline <ON> for Line Select menu display
on the vectorscope CRT.