Figure C- 2: Zone Plate Parameters Window - Tektronix AWVG1 User Manual

K Parameter
X
AWVG1 Wideband Video Generator User Manual
Signals window). In this example, circle frequency is the pattern control
parameter, and the dependent parameters are: K

Figure C- 2: Zone plate Parameters window

TG 2000 display:
Units:
K denotes the initial constant horizontal frequency of the pattern. To see the
X
effects of changing this coefficient, set a waveform monitor to view the video
lines. The units are cycles per active picture height. The number of cycles in a
line depends on the width-to-height aspect ratio of the active video standard. For
example, K = 9.0 results in approximately 12 cycles per line in a standard with
X
a 4:3 aspect ratio; the same setting yields about 16 cycles per line when the ratio
is 16:9.
To estimate the equivalent absolute frequency of the sine wave (to convert from
c/aph to c/s, or Hz), use the formula
≅ K × R × R
f
eq aspect
X l:av
where
is the aspect ratio (width ÷ height),
R
aspect
is the number of lines per frame,
N
lines
is the frame rate, and
f
frame
is the ratio of line length to the length of the active video.
R
l:av
The maximum frequency is (±) half of the active video standard's sampling
frequency. In standards that use a 72.0 MHz clock, for example, the maximum
value of K will correspond to a sine frequency of 36.0 MHz.
X
The Horizontal Sine zone plate signal is a K
, K
X
KX (H freq)
c/aph (cycles per average picture height)
× N × f
lines frame
-only zone plate (see Figure C- -3).
X
Appendix C: Zone Plates
2 2
, K , K , and K .
X XY Y Y
C- 3