Figure 3-11 and Figure 3-12 show example data capture time-domain display and FFT display, respectively. In this step, the necessary updates to the Data Capture settings are made to capture the time domain data and to get a good frequency domain result. First, the ENABLE SYNC button is clicked to generate a synchronization (SYNC) signal. The SYNC signal is only required once during power-up, or if the SMPL_CLK frequency is changed. The SYNC signal resets the internal analog channel selection logic and aligns the FCLKOUT signal to the data frame. Next, update the number of samples to at least 32k to get good frequency domain results (for example, accurate FFT display, SNR data, and THD data). The Input Frequency needs to be set to the frequency of the applied input signal.

When these changes are made, press the Start Capture button to collect time domain and frequency domain data. The Data Plot tab shows the time domain data and the FFT Plot tab shows the frequency domain data. The FFT plot window also shows the SNR, THD and SINAD performance measurements. Different channel data can be shown or hidden using the Channels tab above the plot.

Figure 3-11 Time Domain Data

Figure 3-12 FFT Data