Tektronix SPG8000A, User Manual

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116 SPG8000A User Manual
Figure 32: A “K
Y
2
-only” zone plate
Amplitude parameter
Display name: Amplitude
Units: mV
Use this parameter to adjust the zone plate signal amplitude from 0.0 mV to
798.0 mV, in 0.5 mV increments. The default value is 700 mV.
K parameter Display name: K (Phase)
Units: cycles
The K
∅
parameter is the initial phase of the pattern; it cannot create a pattern
by itself. To see the effects of this adjustment, first set the K
X
coefficient to
approximately 0.75 and set a waveform monitor to view the line waveform.
Then adjust K
∅
. The sine wave will begin on each line at the selected point in
the cycle. Note that 0.25 cycle corresponds to a phase of 90 degrees (or π/2
radians); recall that the sine of 90° is 1.0 and the sine of – 90° is –1.0. When
K
∅
= 0.25, the pattern will begin in the upper left corner of the screen as white;
when K
∅
= – 0.25, the beginning will be Black.
K
X
parameter Display name: KX (H Freq.)
Units: cycles/active picture height (c/aph)
K
X
denotes the initial constant horizontal frequency of the pattern. To see the
effects of changing this coefficient, set a waveform monitor to view the video
lines. Note that the units are cycles per active picture height. The number of
cycles in a line will depend on the width -to- height aspect ratio of the active
format. For example, K
X
= 9.0 will result in approximately 12 cycles per line
in a format with a 4:3 aspect ratio; the same setting will yield about 16 cycles
per line when the ratio is 16:9.
To estimate the equivalent absolute frequency of the sine wave (for example to
conve rt from c/aph to c/s, or Hz), use the formula