Specifications

It is
not
necessary
to display
Channel
1
or Channel 2 to
obtain CH 1 or CH 2 triggering.
Whenever
the AC-GND-DC
switch
for
the
channel is not in GND,
the
input
amplifier
and trigger
channel
are active,
regardlesss
of
the
selection of
VERT MODE
pushbuttons.
ADD MODE.
A
single-channel trigger signal
amplitude
is
not
affected
by the
contribution
of
the
other channel to an
ADD
mode
display. When
the ADD mode
with
CH 2
in-
verted
is used
to compare
two
video
waveforms
by subtrac-
tion,
the
CH 1 or
CH 2 signal to the
Sync Separator
will
be
adequate
for
stable triggering
providing
the
individual
channel
signal
(when
displayed
alone)
meets
the signal
requirements.
When
the
ADD
mode
is
used
to display a signal
from
two sides of a balanced line, the A TRIGGER
SOURCE
switch
NORM
(composite
vertical)
position
may be used if
neither
Channel
signal alone
is
of
sufficient amplitude
for
stable sync separation and triggering.
Typical Operation
ln
a
typical
operating
mode for
the Option 05
instru-
ment, the
A
Sweep
establishes
the basic
frame
and
field
presentation,
and the
B
Sweep allows
detailed observa-
tion
and
measurement
of
various
portions
of the
video
waveform.
To obtain stable displays
free
of
interlace
jitter
(for
systems
which
have
2:1
interlace),
the A TIME/DlV
switch
should
be
set to display
an odd number
of
fields,
plus
a
fraction
of a
field,
in
the
unmagnified
display.
For
50
and 60
Hz
field
rates,
the
2
ms/div
setting is usually
selected.
For
some
PAL
system observations,
a setting of
5
ms/div
(approximately
2%
field
display), with
the
A
TRIGGER
HOLDOFF control
set to
approximately
the
four
o'clock
position (additional
one-field holdoff),
may
be
desirable
to
maintain
a stable
display relationship
to the
four-field
PAL
burst-blanking
sequence.
All detail measure-
ments
are
then
made
with
B Sweep, using
the
B
DLY'Dor
ALT Horizontal
Display, with
the B TRIGGER
SOURCE
switch
set to either
STARTS AFTER
DE
LAY
(continuously
variable
B
Sweep
start
point)
or to
TV LINE
(B
Sweep
starts
after the
leading
edge
of the
next hori-
zontal
sync
pulse
'following
the
delay
interval
set
by
the
DELAY TIME POSITION
control
and the A TIME/DIV
switch setting).
Because the
leading
edge
of the sync
pulse
will not
be
displayed,
the
typical B TIME/DlV
setting
for
width mea-
surements
on
front
porch,
back
porch
and
horizontal
blanking
intervals, horizontal
sync, serration, and equaliz-
ing
pulses
will be 10
psldivision
to allow display
of two
consecutive
pulses.
Use
the 10X
Magnifier
to display the
second
pulse
at
1
psldivision.
For
rise
and fall
time
measurements
on blanking
and
sync waveforms,
trigger the A or
B Sweep directly from
the
displayed
waveform
(avoiding
the
processing
delay
of the
sync
separator).
This
permits
viewing
the
triggering edge
at
sweep rates from
0.5 to
0.02
ps/division.
@
4658/DM44
Operators
103