Chapter 6 6-101
Front-Panel Key Reference
Trig
TV Trig Setup Option B7B (TV Trigger and Picture on Screen) only. Accesses the setup
functions for TV Trigger.
Field Allows you to determine how the fields of the TV
picture signal will be affected by the trigger system.
One complete TV image consists of one frame of 525 or
625 horizontal lines depending on the TV standard
being used. Each frame is composed of two fields of
interlacing lines, each consisting of 262 1/2 lines (or 312
1/2 lines). The fields are called Field One and Field
Two. Field One is viewed as having 263 lines (or 313
lines) and Field Two is viewed as having 262 lines (or
312 lines).
For the 525 line NTSC video standard, we refer to TV
lines as follows (these are the Field Modes):
Entire Frame, lines 1 to 525
Field One, lines 1 to 263
Field Two, lines 1 to 262 (note that this really refers
to “actual” lines 264 to 525)
For the 625 line PAL and SECAM video standards, we
refer to TV lines as follows:
Entire Frame, lines 1 to 625
Field One, lines 1 to 313
Field Two, lines 314 to 625
As the Field is changed, the appropriate value for Line
is chosen to keep triggering on the same line as before,
or if this is not possible, the corresponding line in the
new Field. For example, suppose line 264 is selected
while in the NTSC-M standard and the Entire Frame
mode. This is the first line in Field Two. If Field Two is
then selected, the Line number changes to Line 1, the
same actual line in the TV signal. If Field One is then
selected, the line number stays at 1, but now we are
triggering in the first line in Field One. The only
exception to this is if we are on the last line of Field
One and change to Field Two. In this case, we go to the
last line in Field Two. Key Access:
Trig, TV Trig Setup
Entire Frame
Causes the selected line number to be viewed as an
offset into the entire frame starting with line 1, the first
line in Field One. Key Access:
Trig, TV Trig Setup, Field
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