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R

IGOL 

T

ECHNOLOGIES USA 

I

NC  

877-4-RIGOL-1   How-To 

Guide 

 

[email protected]

 

www.rigolna.com

 

 

 

 

 

 

 

 

 

 

 
 

 

 
 
 
 
 
 


     

Oscilloscope

 

Signal

 

Analysis

 

Using

 

FFTs

 

 

 
 
 

Application Notes 

Comparison Guides 

FAQs 

How-To Guides 

Programming Manuals 

Quick Start Guides 

Support Information 

User’s Guides 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Summary of Contents for DS6104

Page 1: ...C 877 4 RIGOL 1 How To Guide info rigol com www rigolna com Oscilloscope Signal Analysis Using FFTs Application Notes Comparison Guides FAQs How To Guides Programming Manuals Quick Start Guides Support Information User s Guides ...

Page 2: ...r usage of FFT waveforms are z Measuring harmonic content and distortion in systems z Characterizing noise in DC power supplies z Analyzing vibration How to obtain a waveform s FFT In this example an FFT will be generated for the 1 KHz square wave acquired on Channel 1 as seen below This signal can be duplicated on any Rigol scope by attaching the probe to the square wave generator port on the fro...

Page 3: ...uide info rigol com www rigolna com Press the MATH button a menu will appear on the side then select FFT and set the source to Channel 1 A Fast Fourier Transform of the current signal on Channel 1 will appear in the Purple color below the square wave ...

Page 4: ...s is beneficial because it provides a log scale For those not used to logarithmic scaling look at the screenshot above In the split screen mode shown there are 8 vertical divisions dedicated to the FFT Here are the values at the top of each division given the 200 mVrms div setting and the position of the zero marker on the left at the top of the bottom division Divisions down from top of FFT scree...

Page 5: ...Vrms 1 0 dBVrms 1 Vrms at the position marker 2 10 dBVrms 316 Vrms 3 20 dBVrms 1 Vrms 4 30 dBVrms 0316 Vrms 5 40 dBVrms 01 Vrms 6 50 dBVrms 00316 mVrms 7 60 dBVrms 001 mVrms 8 70 dBVrms 000316 mVrms To understand this fully the formula to derive the dBVrms value is as follows dBVrms 20 log Vrms VREF where VREF in this case is 1 Vrms so it can be simplified to dBVrms 20 log Vrms Consequently when l...

Page 6: ...per division of the FFT are always in frequency The above screen shot shows 1 25 KHz per division In this display the left side of the screen is always at DC or 0 Hz Each division to the right then marks the set value In this case the divisions would be 0 Hz 1 25 KHz 2 5 KHz 3 75 KHz 5 KHz and so on How to save a waveform s FFT To save an FFT to the scope or a USB drive the FFT must be saved as a ...

Page 7: ...m select save To save the FFT waveform to a USB drive press the Location button the Location now switches to External as in the figure below Upon selecting Save select the file to save the waveform to and then exit upon completion Reference waveforms can then be recalled at a later time to compare signals ...

Page 8: ...nal With a variety of capabilities to change ranges units and display mode as well as saving and recalling waveforms Rigol oscilloscopes can make frequency measurements easily and quickly using the included FFT function For more information or questions contact us directly at Rigol Technologies USA 7401 First Place Suite N Oakwood Village OH 44146 You can reach us directly at 440 232 4488 877 4 RI...

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