Tektronix 455, Instruction Manual, Page: 112 / 246

Instrument Options—455/A2/B2
3. Set the X I 0 MAG button to the in position and horizon­
ta lly position the display desired. This provides sufficient
resolution to identify the field.
horizontal sync pulse. The Field 1 picture starts w ith a full
line of video.
4. If the displayed field is not the one desired, m om entarily
switch the A SLOPE to the opposite polarity several times
until the desired field is displayed.
Field 1 lines are numbered 1—263, starting at the leading
edge o f the firs t equalizing pulse. The first regular horizontal
sync pulse after the second equalizing interval is the start of
line 10.
5. Horizontally position the display until the desired line Field 2 starts w ith an equalizing pulse a half-line interval
becomes visible. from the preceding horizontal sync pulse. The Field 2
picture starts w ith a half line o f video.
6. Adjust the D E L A Y TIM E POS control to move the in­
tensified zone to the desired line. It may be desirable to set
the X I 0 MAG button to the unmagnified (button out)
position to locate the intensified zone. With the X I 0 MAG
button out, use the D E L A Y TIM E POS control to move the
intensified zone to the horizontal center of the crt. When
the X I 0 MAG button is again set to the in position, the
intensified zone w ill remain in the viewing area.
7. When the desired line is intensified, set the HORIZ
DISPLAY switch to B D LY 'D . This displays the desired
line.
Field 2 lines are number 1—262, starting at the leading edge
o f the second equalizing pulse. A fter the second equalizing
interval, the firs t fu ll line is line 9.
CCIR System B (including PAL)
In most 625-line, 50 Hz field-rate systems, identification of
parts o f the picture relies prim arily on continuous line
numbering rather than on field-and-line identification, except
fo r PAL systems.
8. If there is too much jitte r, set the B SOURCE switch to
the TV LINE position and adjust the B LEVEL control for
a stable display.
Two Frame A Sweep Cycle
If PAL burst blanking is to be checked, use the same proce­
dure as fo r a one-frame A Sweep cycle w ith the follow ing
exceptions: 1
1. Set the A T IM E /D IV switch to 5 ms instead o f 2 ms.
The CCIR frame starts w ith the first (wide) vertical sync
pulse follow ing a field which ends w ith a half-line o f video.
The first line after the second equalizing interval is line 6;
the first picture line is line 23 (half-line of video). The first
field of the frame contains lines 1 through the first half of
line 313, the picture ending w ith a fu ll line o f video (line
310).
The second field of the frame commences w ith the leading
edge of the first (wide) vertical sync pulse (middle o f "lin e "
313), and runs through line 625 (end o f equalizing interval).
The first fu ll line after the equalizing interval is line 318;
the picture starts on line 336 (full line).
2. Adjust the A TRIGGER HOLDOFF control fo r a display The first field is referred to as "o d d ", the second field as
locked on a given field (increase hold o ff tim e by 1 field). "even". Note that the identification systems fo r System M
and System B are opposite. 3
3. Momentarily switch the A SLOPE switch to the opposite
polarity several times until the desired field is displayed in
|n the four-field PAL sequence w ith Bruch Sequence Color-
the desired position. burst blanking, the fields are identified as follows:
ID E N T IF Y IN G FIELDS, FRAMES, A N D LINES
NTSC (CCIR System M)
Field 1 is defined as the field whose firs t equalizing pulse is
one fu ll horizontal interval (63.5 /us) from the preceding
Field 1: Field which follows a field ending in a half-line of
video, and which preceding field has color burst on
the last fu ll line. Field 1 lines are 1 through 312
and half o f line 313. Color burst starts on line 7
o f Field 1; a half-line o f video appears on line 23.
Option 5 Page 4
REV. A, OCT 1975