Quantum Data 881, User Manual

Page: 497 / 1144

882 Video Test Instrument User Guide (Rev A.35) 119
Operating special sync for probe pulse
Configuring the probe feature involves positioning the probe pulse in the desired location
on the video frame. You can do this using either the generator front panel or the command
line interface. The front panel is most convenient if you are near the generator and not
using a computer or terminal. Alternatively, you can control the generator through the
command line interface either locally or remotely through the serial connection or through
a Telnet session.
Probe coordinate numbering
Unlike ITU and SMPTE standards, the Quantum Data standard counts pixels, lines, and
coordinates beginning with the number zero (not one) to improve the mapping between
video signal specifications and modern computer graphics coordinates. The television
standards are accounted for by suppressing any half-active line that appears in an
equalizing interval and lengthening (to a full line) any half-active line that begins in the
active portion of a field. Vertical counting always begins with the leading edge of blanking
of the first field (not vertical sync). The first field is always defined as the field that includes
the top line of the displayed picture (Y:0). This definition is always true whether the total
number of active lines is odd or even.
With interlaced scanning, lines continue to be numbered sequentially throughout the
frame, beginning with the leading edge of blanking of the first field. Therefore, the first two
lines of blanking in the first field are numbered L:0 followed by L:1. If you have 525 total
lines and 486 of those are active, for example, the first two (blank) lines of the second field
would be numbered L:262 and L:263. The Y position continues to follow the visual order of
lines going from the top to the bottom of the screen. If the last line of blanking in the first
field is L:18, then L:19 corresponds to Y:0, L:20 to Y:2, L:21 to Y:4 and so on. In the
second field, L:282 would correspond to Y:1, L:283 to Y:3, L:284 to Y:5 and so on.
Configuring the probe feature
This section describes how to configure the probe feature. Configuring the probe feature
entails enabling the probe, configuring the sensitivity for traveling through the frame, and
identifying the line(s) on which the probe is present.
To configure the probe feature:
1. Press the Tools key. The following menu appears on the generator’s display:
System
Sequence
Probe
AFC
Probe