Owon VDS1022l User Manual page 28

2. Click to show Function menu, choose "Math". Check "Math".
3. Choose the factors and operator. Select the voltage division of M. The software transforms the waveform data of the two factors into selected
voltage division of M and calculates. The green calculated waveform M is displayed in the screen.
Using FFT function
The FFT (fast Fourier transform) math function mathematically converts a time-domain waveform into its frequency components. It is very useful
for analyzing the input signal on Oscilloscope. You can match these frequencies with known system frequencies, such as system clocks,
oscillators, or power supplies.
FFT function in this oscilloscope transforms 2048 data points of the time-domain signal into its frequency components mathematically and the
final frequency contains 1024 points ranging from 0 Hz to Nyquist frequency.
Taking the FFT operation for example, the operation steps are as follows:
1. Click to show Function menu, choose "Math". Check "FFT". The user interface is switched into Three View mode.
2. Set "Channel", "Window", "Format", "Scale", "Frequency Base".
3. You can drag anywhere in FFT window to move the signal up and down and side to side.
To select the FFT window
There are four FFT windows. Each one has trade-offs between frequency resolution and magnitude accuracy. What you want to measure and
your source signal characteristics help you to determine which window to use. Use the following guidelines to select the best window.
Type
Better solution for magnitude than Rectangle, and good for frequency as well. It has slightly better frequency
resolution than Hanning.
Recommend to use for:
Hamming
 Sine, periodic and narrow band random noise.
 Transients or bursts where the signal levels before and after the event are significantly different.
Best solution for frequency, worst for magnitude.
Best type for measuring the frequency spectrum of non-repetitive signals and measuring frequency components
near DC.
Rectangl
Recommend to use for:
e
 Transients or bursts, the signal level before and after the event are nearly equal.
 Equal-amplitude sine waves with frequencies those are very close.
 Broadband random noise with a relatively slow varying spectrum.
Best solution for magnitude, worst for frequency.
Blackma
Recommend to use for:
n
 Single frequency waveforms, to find higher order harmonics.
Characteristics
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Window