Lambda SR1, Operation Manual, Page: 171 / 317

SR1 Operation 171
© 2014 Stanford Research Systems
2.4.8 Histogram Analyzer
The Histogram Analyzer calculates input amplitude histograms of both channels of the selected input
domain. The histogram analyzer divides the input amplitude range into a user specified number of
bins .
The histogram is formed by examining the amplitude of samples of the input data stream, determining
the bin the samples belongs in, and incrementing the amplitude of that bin. This process continues for a
predetermined number of input samples after which the histogram is displayed and the process repeats.
SR1's Histogram Analyzer also has the capability of calculating a real-time gaussian fit to the histogram
data and displaying it alongside the histogram.
Histogram Analyzer Outputs
Measurement Description
Time Record A,B The sequence of input samples for each input channel.
Histogram A,B The input amplitude histograms for each input channel.
Probability A,B The histogram normalized to the total number of bins in the histogram. Each bin
amplitude then represents the probability that the input amplitude falls within the
limits of that bin.
Fit A, B The best-fit gaussian to the the probability histograms.
Mean A,B The Average value of the input samples for each channel.
Sigma A,B The Standard Deviation of the input samples for each channel.
Example Histograms
The histogram provides a different perspective on audio signals compared FFTs or standard Time
Domain techniques. As an example, consider the histograms below:
Histogram of 997 Hz Digital Sine