Ensemble Designs 7405 HD Test Signal Generator - Manual (Page 20)

Timing Test Patterns
Timing test patterns are used to evaluate blanking area, field location, relative luma and
chroma timing, and cositing.
Blanking Markers
The analog blanking markers test pattern draws a box around each field to show
the limits of blanking in composite systems. The size of the box is different for
NTSC than for PAL. In NTSC, the top of the field is at 21/284 and the bottom is at
262/525. In PAL, the top of the field is at 24/337 and the bottom is at 310/622.
The left and right markers are separated from digital blanking, which is narrower,
by a step so that actually blanking edges can be observed after passing through a
process that imposes blanking.
Cosite
The cosite test pattern assists in determining that the luminance and chrominance
parts of a digital signal are occurring in the appropriate relative time.
The vertical magenta pinstripe consists of a single cosite pulse in Y, Cb and Cr.
Because they are cosited and are only one sample wide, a mistiming of these com-
ponents will not appear magenta on a monitor. Cb and Cr can be determined easily
on a waveform monitor because Cb is smaller than Cr. The levels are as follows:
Y-1B7h, Cb-3C0h, Cr-340h. The pinstripe is also useful because it is in the middle
of the line.
Miscellaneous Test Patterns
The following test patterns have special purposes.
Black
A standard black signal.
Crosshatch
The crosshatch test pattern consists of horizontal and vertical lines organized in a
grid. This test pattern is used to evaluate monitor linearity and distortion.
SafeTitle
The safetitle test pattern identifies safe area in a video monitor for titles. If the
title stays inside the safe area, then monitors will always show the complete title
uncropped. The safe title pattern also shows the center of the visible area.
Aspect Ratio
When viewed on a component vectorscope, the unit circle test pattern displays a
circle of constant radius. This test pattern is useful for evaluating systems that
manipulate chroma such as chroma keyers.
Checkfield
The checkfield or pathological test pattern consists of a flat field of magenta color
that is precisely chosen because it produces long sequences of ones and zeroes in
serial digital systems. Because some systems are not tolerant of long sequences,
this pattern can help to identify those systems. This test signal is very useful for
testing transmission paths.
When a pathological error occurs, this test pattern shows horizontal, intermittent
black lines.
7404-A4
Model 7405 HD Test Signal Generator