Ensemble Designs 7405 HD Test Signal Generator User Manual
Page 19
Black Test Patterns
These test patterns are field field luminance reference levels. Black can be used as a color
black reference signal and the others can be used as flat luminance mattes.
Black
The HD black test pattern is a full-field black signal.
Flat Black 50
A 50 percent black signal creating a gray signal for applications requiring a
neutral background.
Ramp Test Patterns
Ramp test patterns are very useful for evaluating linearity, missing bits, timing errors,
and dynamic range.
If there is a problem with linearity, the ramp will not be a straight line. If there is a
missing bit, the ramp will be broken up into smaller ramps. If there is a timing error,
vertical lines which are often noisy can appear. If there is a dynamic range problem,
clipping will occur at the top or the bottom of the ramp.
Data Ramp
The data ramp test pattern goes from minimum to maximum legal digital values
in one step per sample increments. The ramp therefore restarts part of the way
across the line. Because it uses the entire dynamic range, it is especially useful to
check for clipping in each of the component channels, Y, Cb, and Cr.
5 Step Ramp
The five step ramp test pattern has five steps used for aligning display systems
such as a projector.
Pulse and Bar Test Patterns
This test pattern is used to evaluate transient response and clamp performance. Chroma-
to-luminance delay, short-term distortion, gain, response, and tilt can be measured.
Window
The window test pattern is comprised of a 2T pulse, a modulated 12.5T pulse and a
window bar.
The 2T pulse is used to measure short term distortion such as K2T, and transient
response such as KPB.
The modulated 12.5T pulse is used to evaluate chroma-to-luminance delay. When
viewed on a monitor, the bottom of the chroma envelope ideally appears as a flat
line. Group delay can distort the bottom of the envelope and, with the appropriate
waveform monitor graticule, can be measured.
The bar can be used to measure gain, and is also used to measure short-term dis-
tortion such as K
SD
and tilt such as K
BAR
.
7405-A3
Model 7405 HD Test Signal Generator