5.
In the CHOP sweep mode (PULL CHOP switch
pulled out), the sweep is chopped (switched) between
channel 1 and channel 2. Using CHOP, one channel
does not have to “wait” for a complete swept display
of the other channel. Therefore, portions of both chan-
nel’s waveforms are displayed with the phase relation-
ship between the two waveforms unaltered. Chop
sweep is normally used for low-frequency or low-
speed waveforms at sweep times of 1 ms/div and
slower; or where the phase relationship between chan-
nel 1 and channel 2 requires measurement.
If chop sweep is used at sweep times of 0.2 ms/div and
faster, the chop rate becomes a significant portion of
the sweep and may become visible in the displayed
waveform. However, you may select chop sweep at
any sweep time for special applications.
6.
Adjust the channel 1 and 2
▲
▼
POSition controls to
place the channel 1 trace above the channel 2 trace.
7.
Set the CH 1 and CH 2 VOLTS/DIV controls to a
position that gives 2 to 3 divisions of vertical deflec-
tion for each trace. If the display on the screen is
unsynchronized, refer to the “Triggering” paragraphs
in this section of the manual for procedures for setting
triggering and sweep time controls to obtain a stable
display showing the desired number of waveforms.
8.
When the VERTical MODE switch is set to ADD, the
algebraic sum of CH 1 + CH 2 is displayed as a single
trace. When the PULL INV switch is pulled out, the
algebraic difference of CH 1 – CH 2 is displayed.
9.
If two waveforms have no phase or frequency relation-
ship, there is seldom reason to observe both wave-
forms simultaneously. However, these oscilloscopes
do permit the simultaneous viewing of two such unre-
lated waveforms, using alternate triggering. Refer to
the paragraphs on “Triggering — Trigger SOURCE
Switch” for details on alternate triggering.
TRIGGERING
The Model 2522B Oscilloscope provides versatility in
sync triggering for ability to obtain a stable, jitter-free dis-
play in single-trace, or dual-trace operation. The proper
settings depend upon the type of waveforms being observed
and the type of measurement desired. An explanation of the
various controls which affect synchronization is given to
help you select the proper setting over a wide range of
conditions.
AUTO or NORM Triggering
1.
In the AUTO mode (PULL NORM TRIG pushed in),
automatic sweep operation is selected. In automatic
sweep operation, the sweep generator free-runs to
generate a sweep without a trigger signal. However, it
automatically switches to triggered sweep operation if
an acceptable trigger source signal is present. The
AUTO mode is handy when first setting up the scope
to observe a waveform; it provides sweep for wave-
form observation until other controls can be properly
set. Once the controls are set, operation is often
switched back to the normal triggering mode, since it
is more sensitive. Automatic sweep must be used for
dc measurements and signals of such low amplitude
that they will not trigger the sweep.
2.
In the NORM mode (PULL NORM TRIG pulled
out), normal triggered sweep operation is selected. The
sweep remains at rest until the selected trigger source
signal crosses the threshold level set by the TRIG
LEVEL control. The trigger causes one sweep to be
generated, after which the sweep again remains at rest
until triggered. In the normal triggering mode, there
will be no trace unless an adequate trigger signal is
present. In the ALT VERTICAL MODE of dual-
trace operation with the SOURCE switch also set to
ALT, there will be no trace unless both channel 1 and
channel 2 signals are adequate for triggering. Typi-
cally, signals that produce even one division of vertical
deflection are adequate for normal triggered sweep
operation.
Trigger COUPLING Switch
1.
The AC position is used for most waveforms except
video. The trigger signal is capacitively coupled. Thus,
it blocks the dc component and references the average
of the “changing” portion of the waveform.
2.
The TV H and TV V positions are primarily for
viewing composite video waveforms. Horizontal sync
pulses are selected as trigger when the trigger COU-
PLING switch is set to the TV H position, and vertical
sync pulses are selected as trigger when the trigger
COUPLING switch is set to the TV V position. The
TV H and TV V positions may also be used as low
frequency reject and high frequency reject coupling,
respectively. Additional procedures for observing video
waveforms are given later in this section of the manual.
Trigger SOURCE Switch
The trigger SOURCE switch (CH 1, CH 2, etc.) selects
the signal to be used as the sync trigger.
1.
If the SOURCE switch is set to CH 1 (or CH 2) the
channel 1 (or channel 2) signal becomes the trigger
source regardless of the VERTICAL MODE selec-
tion. CH 1, or CH 2 are often used as the trigger source
for phase or timing comparison measurements.
2.
By setting the SOURCE switch to ALT, alternating
triggering mode is activated. In this mode, the trigger
source alternates between CH 1 and CH 2 with each
sweep. This is convenient for checking amplitudes,
waveshape, or waveform period measurements, and
even permits simultaneous observation of two wave-
forms which are not related in frequency or period.
However, this setting is not suitable for phase or timing
comparison measurements. For such measurements,
both traces must be triggered by the same sync signal.
Alternate triggering can only be used in dual-trace
OPERATING INSTRUCTIONS
13