MLZ2012A3R3W datasheet(30/68 Pages) TI1

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ADS1299EEG-FE Analysis Tools

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Figure 32. Analysis : FFT Graph of Input Short Test

Coherent Frequency Calculator: 1

Coherent sampling in an FFT is defined as F

AIN/FSAMPLE = NWINDOW/NTOTAL, where:

•

AIN is the input frequency

•

FSAMPLE is the sampling frequency of the ADS1299

•

WINDOW is the number of odd integer cycles during a given sampling period

•

TOTAL is the number of data points (in powers of 2) that is used to create the FFT If the conditions for

coherent sampling can be met, the FFT results for a periodic signal will be optimized. The Ideal A

Frequency is a value that is calculated based on the sampling rate, such that the coherent sampling

criteria can be met.

AC Analysis Parameters: 2

This section of the tool allows the user to dictate the number of harmonics, dc leakage bins, harmonic

leakage bins, and fundamental leakage bins that are used in the creation of various histograms. Pressing

the Windowing button, illustrated in Figure 33, allows the user to evaluate the FFT graph under a variety

of different windows. Note that pressing the Reference button toggles between dBFS (decibels, full-scale)

and dBc (decibels to carrier).

EEG Front-End Performance Demonstration Kit

SLAU443 – May 2012

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