ADS8688EVM-PDK Kit Operation
Figure 26. FFT Analysis
Input signal frequency for FFT analysis:
•
Coherent Fi: Is the desired input signal frequency calculated by the GUI for maintaining coherency.
•
Actual Fi: Is the actual signal frequency provided by the analog source to the ADS8688. The user sets
the input signal frequency close to the coherent Fi and enters the set value of the input signal
frequency in the Actual Fi box.
The GUI uses a 7-term Blackman-Harris window to minimize spectral leakage.
6.6
Phase Compensation
The ADS8688EVM GUI includes an analysis page for compensating for the phase of signals captured in
auto mode. When the signals on different channels are sampled in auto mode, a deterministic phase
difference between signals is introduced resulting from the time difference between sampling instants. The
phase difference is dependent on sampling rate, input signal frequency, number of channels, and initial
phase difference. The phase compensation analysis page compensates for the introduced phase
difference and provides the results after phase compensation. For details on phase compensation, refer to
the
TIPD167 Verified Reference Design,
Phase Compensated 8-CH Multiplexed Data Acquisition System
. The phase compensation analysis page can be activated from the
Smart App menu.
displays the phase compensation analysis page.
28
ADS8688EVM-PDK Evaluation Module
SBAU230A – August 2014 – Revised December 2014
Copyright © 2014, Texas Instruments Incorporated
