User`s guide

188 5000 Series Oscilloscope User’s Guide
4 Making Measurements
To isolate an event for frequency measurement The following
figure shows how to use zoom sweep to isolate an event for a
frequency measurement. If the measurement is not possible in
the zoom mode, then the main time base is used. If the
waveform is clipped, it may not be possible to make the
measurement.
Figure 32 Isolating event for Frequency measurement
Period
Period is the time period of the complete waveform cycle. The
time is measured between the middle threshold points of two
consecutive, like-polarity edges. A middle threshold crossing
must also travel through the lower and upper threshold levels
which eliminates runt pulses. The X cursors show what portion
of the waveform is being measured. The Y cursor shows the
middle threshold point.
Fall Time
The fall time of a signal is the time difference between the
crossing of the upper threshold and the crossing of the lower
threshold for a negative-going edge. The X cursor shows the
edge being measured. For maximum measurement accuracy, set