2-4
Front-Panel Overview
Important Oscilloscope Considerations
Whether the oscilloscope is stopped or running, you see more detail as you zoom
in, and less as you zoom out. Zoom means you expand the waveform using
either the main or delayed sweep window. Panning the waveform means you
use the Horizontal Delay time knob( )to move it horizontally. To keep from
losing detail as you zoom out, switch to the Peak Detect acquisition mode.
Peak Detect acquire mode Peak Detect for the 54620-series and for the
54640-series functions as follows:
•54620-series In Peak Detect acquisition mode, any noise, peak, or signal
wider than 5ns will be displayed, regardless of sweep speed. In Normal
acqu isi tio n mo de, at swe ep s pee ds f ast er t han 1 m s/d iv, you wou ld s ee a 5-n s
peak, so peak detect has no effect at swe ep speeds faster than 1 ms/div.
•54640-series In Peak Detect acquisition mode, any noise, peak, or signal
wider than 1ns will be displayed, regardless of sweep speed. In Normal
acquisition mode, at sweep speeds faster than 500 µs/div, you would see a
1-ns peak, so peak detect has no effect at sweep speeds faster than 500 µs/div.
Using Peak Detect and infinite persistence together is a powerful way to find
spurious signals and glitches.
Average acquire mode Averaging is a way to pull a repetitive signal out of
noise. Averaging works better than either a brightness control or a bandwidth
limit because the bandwidth is not reduced except when smoothing (number
of averages=1) is selected.
The simplest averaging is smoothing (number of averages = 1). For example,
on the 54620-series, the sample rate at a Time/Div setting of 2ms/div allows the
extra 5-ns samples to be smoothed together, smoothing the data into one
sample, which is then displayed. Averaging (number of averages > 1) needs a
stable trigger, because in this mode multiple acquisitions are averaged together.
See the “MegaZoom Concepts and Oscilloscope Op eration” chapter for more
information about smoothing.