Channel Selection; Add And Invert; Chop Or Alt - Tektronix 2205 Operator's Manual

Operation
Channel Selection
With the three VERTICAL MODE selectors, you can display com¬
binations of the two vertical channels. When Channel 1 is se¬
lected, the other two MODE switches are not active. When OH 2
is selected, the middle MODE switch (NORM/CH 2 INVERT) be¬
comes active. And when BOTH channels are selected for dis¬
play, all three MODE selectors are active.
ADD and INVERT
Select ADD mode to display the algebraic sum of the CH1 and
CH 2 signals. When you use ADD, the CH 1 and CH 2 VOLTS/
DIV settings should be equal.
Selecting CH 2 INVERT causes the polarity of the CH 2 waveform
to be inverted. This allows you to see the difference between
CH 1 and CH 2 signals on the ADD trace.
CHOP or ALT?
When BOTH channels are selected, the display is time-shared.
The CHOP mode displays each channel for a short time and mul¬
tiplexes during the sweep to give the appearance of displaying
both channels at once. This mode (CHOP) works better than
ALT for sweep speeds slower than 1 ms per division and for
iow-repetition-rate signals that make the display flicker (up to 2
ja.s/division).
The ALT mode displays each channel for the duration of a com¬
plete sweep.- It gives a cleaner display of multiple channels than
CHOP does and is usually preferred at moderate to high sweep
speeds.
Certain trigger conditions, including composite trigger selection,
can cause a display that implies a phase relationship or even
synchronization of independent waveforms. If in doubt about the
relative timing of CH 1 and CH 2 signals, experienced operators
set the TRIGGER SOURCE to either CH 1 or CH 2.
2205 Operator's
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