Teledyne LeCroy AORM - Advanced Optical Recording Measurements - Manual (Page 109)

AORM Software Package
923133 Rev A ISSUED: June 2013
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Determining such peaks is very useful because they indicate the dominant values in a signal.
However, signal noise and the use of a high number of bins relative to the number of parameter
values acquired can give a jagged and spiky histogram, making meaningful peaks hard to
distinguish. The scope analyzes histogram data to distinguish peaks from background noise and
from histogram definition artifacts such as small gaps, which are due to very narrow bins.
Binning and Measurement Accuracy
Histogram bins represent a sub-range of waveform parameter values, or events. The events
represented by a bin may have a value anywhere within its sub-range. However, parameter
measurements of the histogram itself, such as average, assume that all events in a bin have a
single value. The scope uses the center value of each bin’s sub-range in all its calculations. The
greater the number of bins used to subdivide a histogram’s range, the less the potential deviation
between actual event values and those values assumed in histogram parameter calculations.
Nevertheless, using more bins may require performance of a greater number of waveform
parameter measurements in order to populate the bins sufficiently for the identification of a
characteristic histogram distribution.
In addition, very fine-grained binning will result in the creation of gaps between populated bins
that may make determination of peaks difficult.
The oscilloscope’s parameter buffer is very effective for determining the optimal number of bins to
be used. An optimal bin number is one where the change in parameter values is insignificant, and
the histogram distribution does not have a jagged appearance. With this buffer, a histogram can
be dynamically redisplayed as the number of bins is modified by the user. In addition, depending
on the number of bins selected, the change in waveform parameter values can be seen.