HD3G7 HD 3 Gb/s SDI Video Generator module
HD3G7 module z
one plate signals
Zone plate video test patterns, or simply “zone plates”, have become importan t
tools for the evaluation of modern video processing systems and techniques.
They are called zone plates because the classical circular pattern looks like an
optical zone plate (which uses the principles of Fresnel diffraction to
focus and
intensify light). Today, however, the name has been applied to a wide variety of
stationary and “moving” test patterns.
The following figure shows two enlarged optical zone plates. The white areas
are transparent and the black areas are opaque. The precise spacing of the rings
focuses and intensifies light that passes through the plate.
Figure 3-78: Optical zone plates (enlarged)
The HD3G7 module generates electronic zone plate signals, and can be configured
to provide a near infinite number of test patterns. Six basic patterns are predefined
(Circle, Diagonal, Horizontal Sine, Horizontal Sweep, Vertical Sine, and Vertical
Sweep) for convenience. These patterns all have an overall, or pattern control,
parameter.
Pattern control parameters are unique to the specificpredefined signals, and are
only found as the first item of the specific signal menu. User-created zone plate
signals saved as Custom–1 or Custom–2 do not have pattern control parameters.
The dependent parameters are common to all of the zone plate signals, and are
found below the pattern control parameter in the menu for each zone plate signal.
Altering the pattern control parameter will make changes to the test signal while
maintaining the basic pattern. For example, the pattern control parameter for the
Circle zone plate signal is the Circle Frequency parameter. The Circle Frequency
parameter controls the maximum frequency of the circle. You may alter the Circle
Frequency at will, and the system will adjust four other dependent parameters to
maintain the p attern as a circle. However, if you alter the underlying dependent
parameters individually the pattern may change to be something other than a circle.
After changes have been made you can save the new signal as a custom zone
plate signal.
3–172 TG8000 Multiformat Test Signal Generator User Manual
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