Measuring System Performance: Modulation Measurements
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The MODULATION screen allows you to monitor the video depth of
modulation in graphical and precise numerical format. The software shows a
marker at the optimal modulation level (NTSC 87.5%, PAL 90%) to assist
you in making adjustments. You can also listen to the audio modulation of
the tuned channel or frequency.
Fig. 6-8 shows the screen for Video Depth of Modulation, which is the ratio
of peak downward change in modulation to carrier amplitude, expressed as
a percentage.
To measure modulation, use the Navigator menu or press the MOD
measurement mode key.
Fig. 6-9 shows the Video screen. Notice the index arrow on the
left side of the vertical bar graph—(87.5%)—indicates the Video
icon is active.
Fig. 6-9 The MODULATION Video Screen
In the event of weak or bad signal, the screen displays:
ERROR
INSUFFICIENT SIGNAL LEVEL TO
PERFORM THE MEASUREMENT
Pressing the Audio soft key activates the screen shown in Fig.
6-10. A built-in 13 dB amplifier and/or 50 MHz low-pass filter
can also be activated.
MODULATION MEASUREMENTS
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