Digital Multimeter HDM3055 Series Manual

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Histogram with Statistics

Showing statistics (Shift > Math > Statistics) is particularly useful for the histogram display. For example,

in the graphic below, the thick blue line is the average, and each thin blue line represents one standard

deviation from the average.

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The final button on the histogram menu, Clear Readings, clears reading memory and starts a new

histogram.

Histogram Data

The graphic below shows a histogram of frequency measurements. Data is displayed on the left side

of the histogram. In the graphic below, reading from top left downward:

l 3.00000 kHz - present measurement value.

l 105 - Number of samples in the largest bin.

l 17.5% - Percentage of samples in the largest bin.

l Total 599 - Total number of samples.

l # Bins 20 - Total number of bins.

l 0, 2.5k, 5k - (Below the histogram) Range of frequency values.

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The main histogram menu includes a Cumulative softkey that hides or shows a line representing

the cumulative distribution of the histogram data. Note that this line represents all of the data only

when the outer bins are shown; if the outer bins are not shown, the outer bin data is not represented

in the line. The cumulative distribution line always goes from 0 to 100% on the vertical scale,

regardless of the histogram’s scale.

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The image below adds the outer bins to the display. The relatively large number of readings above

the bin range (the cyan bar) causes the bars within the bin range to shrink.

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The Outer Bins softkey displays two additional bins, for readings above and below the bin range.

For example, this image shows the Outer Bins softkey set to Off.

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For Binning Auto, the algorithm starts by continuously readjusting the histogram span based on the

readings coming in, completely re-binning the data whenever a new value comes in outside of the

current span. After acquiring a large number of readings, a new reading outside of the range causes

the bins to be compressed by a factor of two such that the new bin range will cover the new reading.

The number of bins shown is a function of the number of readings received: 0 to 100 readings = 10 bins,

101 to 500 readings = 20 bins, 501 to 1000 readings = 40 bins, 1001 to 5000 readings = 100 bins,

5001 to 10000 readings = 200 bins, >10000 readings = 400 bins.

For Binning Manual, you can set number of bins to 10, 20, 40, 100, 200, or 400. You can specify the

bin range as either Low and High values, or as a Span around a Center value. For example, the

histogram range shown above (from -5 to 4 V) could be specified as a Low of -5 V and a High of 4 V,

or a Center of - 0.5 V and a Span of 9 V.

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Pressing the key, followed by the Display softkey allows you to select the display type:

Binning

The Binning softkey allows you to either let the instrument control how the histogram is binned (automatic binning),

or to manually specify the binning parameters with the Bin Settings softkey. Changing any binning parameter,

or switching between automatic and manual binning, will automatically start the histogram over with new data.

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Histogram

The histogram shows measurement data as a graphical representation of the distribution of measurement

data. Data is grouped in bins represented by vertical bars in the histogram display.

NOTE Autoranging can adversely affect the histogram display when measuring repetitive signals spanning

multiple ranges. To avoid this, select a fixed range when using the histogram display.

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l Default sets the scale to equal the measurement range.

l Auto automatically adjusts the scale to appropriately fit the line currently shown on the screen.

l Manual allows you to configure the scale either as High and Low values or as a Span around a

Center value. For example, a scale from a Low of 0 V to a High of 5 V is equivalent to a Center

of 2.5 V and a Span of 5 V.

If you have enabled limits, the (Limits) softkey also appears. This sets the vertical scale to match

the limits.

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Recent/All

The Recent/All softkey shows either all of the data in the trend chart (All) or just the most recent data

(Recent). Neither selection clears reading memory.

In All mode, the trend chart displays all readings being taken and builds from left to right. After the display

is filled, the data becomes compressed on the left side of the display as new data is added on the right

side of the display.

Scaling

The Vertical Scale softkey specifies how the current vertical scale is determined.

Press Vertical, to change the scaling: