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2-3-5 Additive and Differential Operation
Additive and differential operation are forms two-channel operation where
two signals are combined to display one trace. In additive operation, the resul
tant trace represents the algebraic sum of the CHI and CH2 signals. In differen
tial operation, the resultant trace represents the algebraic difference between
the CHI and CH2 signals.
To set up the Model 7040A for additive operation, proceed as follows
L Set up for dual-trace operation per paragraph 2-3-3 Dual-trace Operation.
2. Make sure both VOLTS/DIV switches (13) and (14) are set to the same position
and the VARIABLE controls (15) and (16) are click-stopped fully clockwise.
If
the signal levels are very different, set both VOLTS/DIV switches to the
position producing a large on-screen display of the highest-amplitude signal.
3. Trigger from the channel having the biggest signal.
4. Pull the CHI Vertical POSITION knob (19), thereby activating the PULL ADD
switch. The single trace resulting is the algebraic sum of the CHI and CH2
signals. Either of both of the Vertical POSITION controls (19) and (20)
can be used to shift the resultant trace.
NOTE :
If
the input signals are in-phase,
the amplitude of the resultant trace will
be the arithmetic sum of the individual
traces (eg., 42 div
+
1.2 div
=
5.4 div)
If
the input signals are 180° out-of-phase,
the amplitude will be the difference(eg.,
4.2 div - 1.2 div
=
3.0 div.)
5.
If
the p-p amplitude of the resultant trace is very small, tum both
VOLTS/DIV switches to increase the display height. Make sure both are
set to the same position.
To set up the Model 7040A. for differential operation do everything just described
and also pull the CH2 Vertical POSITION knob (20) to activate the PULL CH2 INV
switch. The single trace resulting is the algebraic difference of the CHI
and CH2 signals. Now if the input signals are in-phase, the amplitude of
the resultant trace is the arithmetic difference of the individual traces
(eg .• 4.2 div
1.2 div
=
3.0 div.)
If
the input signals are 180 out-of-phase,
the amplitude of the resultant trace is the arithmetic sum of the individual
traces (eg., 4.2 div
+
1.2 div
=
5.4 div)
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