Analog Devices EVAL-ADE7903EBZ, User Manual

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UG-797 EVAL-ADE7903EBZ User Guide
Rev. 0 | Page 10 of 12
WAVEFORM SAMPLING
Figure 15 shows the Waveform Sampling window. This
window provides full access to the ADC outputs (waveforms) of
the
ADE7903 ADC on the board. To display waveforms, follow
these steps:
1. Enter an acquisition time in the Accumulation Time (ms)
box, expressed in milliseconds.
2. Select the
Channels
of the ADE7903 to be visualized by
checking any combination of the Current , Voltage1 , and
Voltage2 boxes. The color of each waveform can be changed
as desired by clicking the color next to the check box.
3. Click Capture to display the waveforms on the plot. After
the data is captured, the check boxes under Channels can
be modified to display any combination of waveforms from
that data capture.
The SDP-B Blackfin board acquires the waveform samples
using the
ADE7903 DREADY signal as an interrupt. The blue
bar above the plot shows the acquisition progress.
To save the waveforms to a file,
1. Click the folder icon below Save File To to select the folder
for the file to be saved.
2. Click Save As .txt to save the waveform data to a file.
The program stores every waveform into a file named
ADE7903_WAVEFORM_xxxx.txt , where xxxx is a number
starting at 0000 and incremented by 1 to keep from overwriting
a past waveform file. The file includes the raw data with the
columns being time, current channel, Voltage Channel 1, and
Voltage Channel 2. The file is semicolon (;) delimited and can
easily be imported into a spreadsheet.
To shift and zoom in on the plot, use the buttons in the bottom
left-hand corner of the plot area.
To enable a Fourier analysis of the acquired waveforms, change
the position of the
Select Analysis switch from Waveforms to
FFT . In this case, the window shown in Figure 16 is enabled.
Only one waveform at a time is visualized in this plot; select the
Channels boxes accordingly.
Select the type of windowing from the Window drop-down
menu: Hanning , Blackman-Harris , or none .
Various FFT Settings can be selected: 0 dB level reference may
be at the signal peak, the theoretical maximum, or at a manual
entry. When selecting
Signal Peak , the plot uses the amplitude
of the maximum peak of the waveform as the 0 dB level and
writes it in the
Manual entry box.
Other selections include the Bandwidth under analysis (default
is between 10 Hz and 4000 Hz), the
Fundamental Frequency
(the default is 50 Hz), the width of the signals extracted for SNR
analysis,
Fund/Harm Sideband Bins (the default is 10 Hz), and
the Number of Harmonics used in the ADC specifications
visualized under the plot (default is 6).
When the FFT plot is visualized, the program calculates and
visualizes the following ADC specifications:

SNR (signal-to-noise ratio)

THD
(total harmonic distortion)

SINAD (signal-to-noise-and-distortion ratio)

SFDR (spurious-free dynamic range)

Signal (rms of the fundamental component)

Noise (rms of the noise)

Harmonics (rms value of all harmonics)
Figure 15. Waveform Sampling
Figure 16. Fourier Analysis
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