Depth Of Modulation - ADInstruments S7200 Operation Manual

AD INSTRUMENTS S7200 TV Signal Analyzer Operation Manual

6.3.1. Depth of Modulation

In analog TV measurement mode, tap the soft button [DOM] to enter Depth of
Modulation menu. Depth of modulation is measured as the percentage of the
total amplitude change of the carrier, as the signal progresses from sync tip to
peak white. You can measure depth of modulation on a TV channel with a
vertical interval test signal (VITS). A test signal transmitted on the VITS of
program video provides a reference to calibrate the video depth of modulation.
Transmission standards require that the DOM ratio be in the range of 87.5%. At
horizontal sync position, the carrier reaches maximum amplitude. At the peak
white color position, the carrier amplitude is 12.5% less than the maximum
amplitude.
Figure 6-18 Snapshot: Depth of Modulation Measurement
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