GW Instek GDS-1000 Series User Manual - Manual (Page 49)

MEASUREMENT
49
Math Operations
The Math operations can add, subtract, or perform FFT on the input
waveforms. The resulted waveform can be measured using the
cursors, and saved or recalled just like normal input signals.
Overview
Addition (+) Adds amplitude of CH1 & CH2 signals.
Subtraction (–) Extracts the amplitude difference between CH1 &
CH2.
FFT Runs FFT calculation on a signal. Four types of
FFT windows are available: Hanning, Flattop,
Rectangular, and Blackman.
Hanning FFT
window Frequency resolution Good
Amplitude resolution Not good
Suitable for.... Frequency measurement on
periodic waveforms
Flattop FFT
window Frequency resolution Not good
Amplitude resolution Good
Suitable for.... Amplitude measurement on
periodic waveforms
Rectangular FFT
window Frequency resolution Very good
Amplitude resolution Bad
Suitable for.... Single-shot phenomenon
(this mode is the same as
having no window at all)
Blackman FFT
window Frequency resolution Bad
Amplitude resolution Very good
Suitable for.... Amplitude measurement on
periodic waveforms