Displaying Fft Spectrum - Hantek DSO5000BM Series User Manual

Digital storage oscilloscope

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Table Of Contents

Table of Contents

To set the FFT display, follow the steps below.

1. Push the MATH MENU button;

2. Set the Operation option to FFT;

3. Select the Math FFT Source channel.

In many situations, the oscilloscope can also generate a useful FFT spectrum despite the YT

waveform not being triggered. This is especially true if the signal is periodic or random (such as

noise).

Note: You should trigger and position transient or burst waveforms as close as possible

to the screen center.

Nyquist Frequency

The highest frequency that any real-time digital oscilloscope can measure without errors is half of

the sample rate, which is called the Nyquist frequency. Frequency information beyond the Nyquist

frequency is undersampled which brings about the FFT aliasing. The math function can convert

the center 2048 points of the time-domain waveform to an FFT spectrum. The resulting FFT

spectrum contains 1024 points from DC (0Hz) to the Nyquist frequency. Usually, the screen

compresses the FFT spectrum horizontally to 250 points, but you can use the FFT Zoom function

to expand the FFT spectrum so that you can clearly view the frequency components at each of

the 1024 data points in the FFT spectrum.

Note: The oscilloscope's vertical response is a little bit larger than its bandwidth (60MHz,

100MHz or 200MHz, depending on the model; or 20MHz when the Bandwidth Limit option

is set to Limited). Therefore, the FFT spectrum can display valid frequency information

above the oscilloscope bandwidth. However, the amplitude information near or above the

bandwidth will not be accurate.

5.3.1.2

Push the MATH MENU button to display the Math menu. Use the options to select the Source

channel, the Window algorithm and the FFT Zoom factor. Only one FFT spectrum can be

displayed at a time.

Math FFT Options

Source

Window

FFT Zoom

DSO5000 Series Digital Storage Oscilloscope User Manual