LeCroy 9300C Series, Operator'S Manual

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10 –4
Zoom, Mathematics and Math Setup
The weight of ‘old’ waveforms in the continuous average
gradually tends to zero (following an exponential rule) at a rate
that decreases as the weight increases.
Summed Averaging
Summed Averaging is the repeated addition, with equal weight,
of successive source waveform records. If a stable trigger is
available, the resulting average has a random noise component
lower than that of a single-shot record.
Whenever the maximum number of sweeps is reached, the
averaging process stops. An even larger number can be
accumulated simply by changing the number in the “SETUP”
“for” menu. However, the other parameters must be left
unchanged or a new averaging calculation will be started.
The process may be interrupted by changing the trigger mode
from NORM to STOP or by turning off the active trace using the
respective buttons. Averaging will be resumed when the inverse
is done. The accumulated average is reset by pushing the
CLEAR SWEEPS button or changing an acquisition parameter
such as input gain, offset, coupling, trigger condition, timebase
or bandwidth limit. The number of current averaged waveforms
of the function or its expansion is shown in the Displayed Trace
label.
When summed averaging is selected, the display is updated at a
reduced rate — about once every 1.5 s — in order to increase
the averaging speed (points and events per second).
Summed averaging can also be done on sequence waveforms
to give the average of the segments. And it can be applied to an
expansion of a sequence segment, giving the segment’s
average waveform over many sequence acquisitions.
Extrema Waveforms
These are computed by a repeated comparison of successive
source waveform records with the already-accumulated extrema
waveform, which consists of a maxima (roof) and a minima
(floor) record. Whenever a given data point of the new
waveform is greater than the corresponding maximum roof-
record value, or less than the corresponding floor value, it
replaces it. Thus the maximum and the minimum envelope of all
waveform records is accumulated.
Roof and Floor records can be displayed individually or together.