Keithley 194 Instruction Manual page 87

OPERATION
Figure 3-27. Typical Digital Oscilloscope
Connections
3.22.4 Dual-Channel Voltmeter
The Model 194 can be equipped for dual-channel opera-
tion by adding an optional Model 1944 A/D Module. When
the instrument is equipped in this manner, each channel
operates independently from one another, with the excep-
tion of the display, front panel controls, and IEEE-488 bus.
Since each channel can be independently programmed,
the Model 194 can be set up to make two entirely different
types of measurements at the same time.
For example, assume a periodic waveform is to be sampled
and analyzed on channel 1, while a DC voltage is to be
monitored for drift with channel 2. Figure 3-28 shows the
basic configuration for this measurement. Each channel
could be programmed for appropriate rate, samples, and
trigger mode. With the periodic waveform, a rapid sampl-
ing rate would probably be required, while a much slower
rate would be required for long-term drift analysis.
Figure 3-28. Dual Channel
OperatiOn
Once data is sampled and stored in the independent
chan-
nel buffers, mathematical functions could be performed
on each channel independently. For example, you may
wish to obtain the RMS value of the waveform sampled
on channel 1, and the average of the DC voltage measured
on channel 2.
3.22.5 Catch a Falling Pulse
The Model 194 lends itself readily to pulse analysis due
to its high sampling rates. Its buffer storage capabilities
allows the instrument to catch rapid pulses and retain them
for additional analysis.
Common pulse measurements include pulse duration, as
well as rise and fall times. Generally, the rise time is de-
fined as the period of time required for the pulse to rise
3-48