Extron Electronics VSC 500_700_700D User Guide - Manual (Page 13)

Oscilloscope Displays
What you see on the oscilloscope while adjusting the VSC to match the genlock signal
depends on the type of signal used, the type of oscilloscope, and the procedure the scope
requires. This section shows some examples of oscilloscope displays.
The following diagram shows the genlock input signal (top) and an out-of-alignment NTSC
composite sync output signal (bottom) displayed on a waveform monitor to check for
alignment. When the phases are aligned, the wave peaks on the bottom waveform should
line up with those in the reference signal above it.
Genlock Input
Signal
NTSC Composite
Output Signal
Figure 5. Superimposed Waveforms
With this method there is no way to know if the signals are 180º out of phase. A delayed
sweep on a time-based scope would allow a more accurate display of the input and output
signal phase relationships.
A vectorscope is more accurate than a waveform monitor. The following diagram shows an
example of a vectorscope display when the horizontal phase is adjusted to align it with the
burst (genlock) vector. Adjust the horizontal phase by rotating the Adjust horizontal
([) knob until the difference between the two vectors is 0º. This example shows black burst
only (with no color). The burst vector is pointing to the left from the center.
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Figure 6. Vectorscope Screen During Horizontal
Phase Adjustment
VSC 500/700/700D User Guide • Installation and Operation 7