Tektronix TG8000 User Manual page 424

SDI7 Dual Channel SD/HD/3G SDI Video Generator module
Table 3-60: SDI7 module zone plate pattern control parameters
Zone plate
signal Pattern control parameter
Circle Circle Frequency (maximum c/aph)
Diagonal Diagonal Frequency (equivalent c/aph)
H Sine Horizontal Frequency (MHz)
H Sweep H Sweep Frequency (maximum MHz, or
multiple)
V Sine Vertical Frequency (c/aph)
V Sweep V Sweep Frequency (maximum c/aph, or
multiple)
3–274
When you first enter the zone plate parameters menu for a signal, the pattern
control parameter for that signal is displayed. The pattern control parameter
controls the basic pattern frequency by adjusting the dependent parameters. For
example, if you change the CIRCLE SWEEP Circle Frequency, the generator
adjusts four of the dependent parameters to keep the circle round.
Parameter definition
The circle frequency is actually the equivalent of the
maximum vertical sinusoid frequency at the very top
and bottom of the screen (see the discussion of the K
parameter). Adjusting the circle frequency has the simple
effect of increasing or decreasing the maximum frequency
at the outer edges of the pattern. However, this adjustment
actually changes the coefficients of four of the zone plate
parameters to keep the pattern round and centered on the
screen.
The diagonal frequency is
horizontal frequencies (c/aph). Adjusting the diagonal sine
frequency changes both the KX and KY coefficients.
The horizontal frequency reported on the display is the real
time frequency of the sine wave that causes the vertical
bar pattern. The maximum frequency is half of the clock
frequency used by the generator for the active video
standard (for example, 74.25 MHz/2 = 37.125 MHz).
For horizontal sweep frequencies up to half of the video
standard's sampling frequency, f
maximum (or swept to) frequency of the sine wave. For
numbers greater than f /2, dividing the displayed value by
s
the sampling frequency will give the number of complete
DC–(f /2)–DC cycles per line. For example, in a standard
s
with sampling frequency of 74.25 MHz, a horizontal sweep
frequency of 148.5 MHz will result in approximately two
complete frequency sweeps across the picture.
The vertical frequency is actually the K
maximum frequency (c/aph) corresponds to the number of
active video lines in a field of the active video standard.
For example, when an 1125-line system is output (which
has 1080 active lines), K
and 540.
The vertical sweep frequency is actually the K
For numbers greater than maximum, dividing the displayed
value by that maximum will give twice the number
of complete DC-max-DC sweeps per field (sweeps =
(K /K )/2). For example, in a standard with 1080 lines per
2
Y Y
field, a vertical sweep frequency of 2160 c/aph
in one complete frequency sweep down the picture.
TG8000 Multiformat Test Signal Generator User Manual
Y
times the vertical and
, the displayed value is the
s
coefficient. The
Y
can be any value between –540
Y
coefficient.
2
Y
would result
2
2