Specifications

46
The scope's digital filter was set to be a low-pass filter with a cutoff frequency of 1.2 kHz. This
effectively removed the higher signal component and lets us measure the amplitude of the
fundamental. The generator was set to 1 Vpp and you can see that is approximately the peak-to-peak
amplitude in waveform A. You can estimate that the peak-to-peak amplitude of the fundamental in A is
about 400 mV and this is confirmed in trace B.
The typical filtering modes are low-pass, high-pass, band-pass, and band-reject.
Pass/fail testing
Some digital scopes provide pass/fail testing capabilities. This feature lets you define an acceptance
region on the scope's display for a signal. If a subsequent signal falls within this acceptance region, the
test is considered passed and a pass counter is incremented (and the scope may have an output port
that can produce a hardware signal indicating this fact). Otherwise, the test is failed and the failure
counter is incremented.
Here's an example of a pass/fail screen from a B&K 2542B oscilloscope:
Figure 34
The black area around the yellow waveform shows the acceptance region (this is created with the use
of the mask controls shown in the picture). The counters at the top left of the screen show how many
total tests have been run and the number of passes and failures. A test is run every time the scope is
triggered. For example, in a manufacturing environment, a circuit board under test could be inserted
into a fixture, a DC power supply turned on, and a test button could be pressed that would provide the
needed input signal(s) and trigger the scope to measure the output signal. The scope's output pass/fail
signal could be used to control hardware such as a robot that moved the circuit board to the next
station (or e.g. put it into a failure queue for subsequent analysis).
All content Copyright © B&K Precision Corporation, except where otherwise noted.
Copying/reprinting/republishing without express written consent prohibited.