5-9
Making Measurements
To reduce the random noise on a signal
Smoothing (# Avgs=1) or High-resolution mode
The term smoothing is an oversampling technique used when the digitizer
sampling rate is faster than the rate at that samples are being stored into
acquisition memory. The sample rate for the 54620-series is 200 MSa/s for
single channel or 100 MSa/s with channel pairs 1 and 2, 3 and 4, or pod 1 and
pod 2 running. The sample rate for the 54640-series is 2 GSa/s for single channel
or 1 GSa/s with channel pairs 1 and 2
For example, if the scope is sampling at 200MSa/s, yet storing the samples at
1 MSa/s, it needs to store only 1 out of every 200 samples. When smoothing is
used, the slower the sweep speed, the greater the number of sam ples that are
averaged together for each display point. This tends to reduce random noise on
the input signal, which produces a smoother trace on the screen.
If you cannot acquire multiple triggers, you can still reduce noise and increase
resolution at slower sweep speeds by setti ng # Avgs to 1.
54620-series
Sweep speed 54640-series
Sweep speed Bits of resolution
(# Avgs=1)
2 us/div 200 ns/div 8
5 us/div 1 us/div 9
20 us/div 5 us/div 10
100 us/div 20 us/div 11
500 us/div 100 us/div 12