Cirrus Logic CDB5480U - Manual (Page 32)

CDB5480U
32 DS893DB5
2.8.1.9 Collecting Data Sets
To collect a sample data set:
1. In the Data Collection window, press the Config button to bring up the Configuration window and view the
current settings.
2. Select the appropriate settings from the available options (see “Configuration Window” on page 31) and
press the Accept button.
3. The Data Collection window should still be visible. Press the Collect button to begin collecting data.
4. Once the data has been collected, it can be analyzed, printed, or saved to disk.
2.8.1.10 Analyzing Data
The evaluation software provides three types of analysis tests: Time Domain, Frequency Domain, and
Histogram. The time domain analysis processes acquired conversions to produce a plot of magnitude
versus conversion sample number. The frequency domain analysis processes acquired conversions to
produce a plot of magnitude versus frequency using the Fast-Fourier transform (results up to Fs/2 are
calculated and plotted). Also statistical noise calculations are calculated and displayed. The histogram
analysis processes acquired conversions to produce a histogram plot. Statistical noise calculations are
also calculated and displayed.
2.8.1.11 Histogram Information
The following is a description of the indicators associated with histogram analysis. Histograms can be
plotted in the Data Collection window by setting the analysis type pull-down menu to Histogram. See
Figure 27. The histogram plot information includes:
• BIN: displays the x-axis value of the cursor on the histogram.
• MAGNITUDE: displays the y-axis value of the cursor on the histogram.
• MEAN: indicates the mean of the data sample set. The mean is calculated using the following
formula:
• STD_DEV: indicates the standard deviation of the collected data set. The standard deviation is
calculated using the following formula:
• VARIANCE: indicates the variance of the current data set. The variance is calculated using the
following formula:
• MAXIMUM: indicates the maximum value of the collected data set.
Mean
X
i
i 0 =
n 1 –

n
---------------------- =
STDDEV
X
i
Mean –  
2
i 0 =
n 1 –

n
----------------------------------------------------- =
Variance
X
i
Mean –  
2
i 0 =
n 1 –

n
--------------------------------------------------- =