Technical data

26 4000 X-Series Oscilloscopes Advanced Training Guide
2 Oscilloscope Familiarization Labs
signal that has a 50% duty cycle should consist of a fundamental sine
wave frequency component (signal’s repetitive frequency), plus its odd
harmonics (3rd, 5th, 7th, etc.). Note that non- ideal square waves will also
include lower-level even harmonics. Let’s now verify the frequencies of the
fundamental and odd harmonics.
23 Press the [Cursors] front panel key (near the Cursors knob).
24 Press the Source softkey and change the Source from channel-1 to Math:
f(t)
25 Push the Cursors knob and select the X1 cursor.
26 Move the X1 cursor so that it is on top of the highest frequency peak
(near the left side of the display).
27 On the right of the screen, select the X2 cursor.
28 Move the X2 cursor until it is on top of the 2nd highest frequency peak.
The frequencies at the X1 and X2 cursor locations are displayed near the
bottom of the scope’s display.
Let’s now verify the fundamental frequency of this signal using the scope’s
“counter” measurement.
29 Press the [Meas] front panel key.
30 Press the Type softkey and select Counter.
The “counter” measurement measures the average frequency over a fixed
gate time to provide a very high resolution (5 digits) measure of frequency,
similar to a standalone counter. But the measurement requires that the
input signal be repetitive.
The “frequency” measurement measures the period of just one cycle of the
signal, and then computes the frequency by taking the reciprocal.