C
–1
Appendix C: Fast Fourier Transform (FFT)
C
When and How to Use FFT
The WP02 Spectral Analysis package, with FFT (Fast
Fourier Transform), reveals signal characteristics not
visible in the time domain and adds the power of frequency
domain analysis to your oscilloscope. FFT converts a time
domain waveform into frequency domain spectra similar to
those of a spectrum analyzer, but with important
differences and added benefits.
Why Use FFT?
For a large class of signals, greater insight can be gained by
looking at spectral representation rather than time description.
Signals encountered in the frequency response of amplifiers,
oscillator phase noise and those in mechanical vibration analysis
— to mention just some applications — are easier to observe in
the frequency domain.
If sampling is done at a rate fast enough to faithfully
approximate the original waveform (usually five times the
highest frequency component in the signal), the resulting
discrete data series will uniquely describe the analog signal.
This is of particular value when dealing with transient signals
because, unlike FFT, conventional swept spectrum analyzers
cannot handle them.
Theory Behind FFT
Spectral analysis theory assumes that the signal for
transformation be of infinite duration. Since no physical signal
can meet this condition, a useful assumption for reconciling
theory and practice is to view the signal as consisting of an
infinite series of replica of itself. These replica are multiplied by
a rectangular window (the display grid) that is zero outside of the
observation grid.
Ø
For an explanation of FFT terms: see the Glossary
on page C–17
Ø
Using FFT Functions: see page C–9
Ø
FFT Algorithms: page C–14
Содержание 9300C Series
Страница 1: ...Operator s Manual LeCroy 9300C Series Digital Oscilloscopes Revision A January 1998 ...
Страница 8: ...1 3 billed for parts and labor related to the repair work and for shipping ...
Страница 18: ...4 1 4 Introduction to the Controls Two Channel Front Panel ...
Страница 19: ...4 2 Introduction to the Controls Four Channel Front Panel ...
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Страница 111: ...11 3 Dual Quad ...
Страница 112: ...11 4 Display Parameter s XY only ...
Страница 113: ...11 5 XY Single XY Dual ...
Страница 127: ...12 10 UTILITIES Protected will be displayed on the upper part of the grid whenever the medium is accessed for writing ...
Страница 138: ...12 21 Ø FLASH UPDATE Offering the Update from and Update Program menus illustrated next page ...
Страница 139: ...12 22 UTILITIES The full screen warning message shown when FLASH UPDATE has been selected ...
Страница 142: ...13 2 WAVEFORM STORE RECALL ...
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Страница 189: ...A 15 9344C Series 9350C Series 9354C Series 9354CTM 50 000x 9344CL 9350CL 9354CL 100 000x ...
Страница 200: ...A 26 Specifications FourChannelsCombined by PP094 Adapter Peak Detect OFF 4 GS s 400k 2M 8M One PP094 input ...
Страница 252: ...E 6 Appendix E ...
Страница 275: ...Index 9370C 9374C Series A 18 9384C Series A 24 Zoom menu 10 7 Zoom of Math Functions 10 1 ...