4Mpts FFT analysis sample points

　　Some signal characteristics are difficult to judge in the time domain, but are easy to analyze in the frequency domain. For example, when analyzing the noise characteristics of a DC power supply, the Fourier analysis function that can convert time domain signals into frequency domain signals is required.

　　The ZDS2022 oscilloscope has up to 4Mpts of FFT analysis sample points and a frequency resolution of up to 250Hz. This article takes a square wave as an input signal to demonstrate how to perform Fourier analysis on a waveform.

　　Figure 1 Selecting FFT operation

　　First, input a sine wave signal and make the signal display stably on the screen. Press the [Math] key and select FFT in the mode selection. Since the ZDS2022 oscilloscope uses an optimized algorithm and a powerful DSP processor, the data processing capability is greatly enhanced. In the blink of an eye, the FFT analysis spectrum diagram and the analysis results in the spectrum table are automatically displayed. Rotate knob B to view the top 20 frequency points with the largest energy listed in the spectrum table. By observing the spectrum diagram, you can intuitively see the various frequency components of the waveform.

　　Figure 2 FFT calculation results display

　　Rotate the M1 knob to adjust the vertical or horizontal position of the spectrum graph. Short press the M1 knob to switch between horizontal and vertical directions. Rotate the M2 knob to adjust the vertical or horizontal offset of the spectrum graph. Short press the M2 knob to reset the vertical or horizontal offset, which is very helpful for specific analysis of the spectrum graph!

　　The 4M-point FFT analysis capability of the ZDS2022 oscilloscope is comparable to that of a spectrum analyzer! Whether it is looking for crosstalk problems or distortion problems caused by amplifier nonlinearity in analog waveforms, it is a very practical function!