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How to calculate averaging count according to VBW/RBW ratio?

Question asked by Macree on Mar 26, 2017
Latest reply on Apr 25, 2017 by Macree

Hi everyone.I have a question about VBW function in the pna-x spectrum analyzer option.It uses FFT method to transfer signal from time domain to frequency domain,so it can't use low-pass filter as VBW filter.To solve the problem,trace average is used instead.The question is ,what's the mathematical relationship between RBW/VBW ratio and average count?Is there a function I can use to calculate average number according to RBW/VBW ratio?And is the averaging count related to RBW shape and averaging type?

 

http://www.ni.com/tutorial/13869/en/  This is an file I read about calculating averaging count,but I'm not sure it's right or not.Dose PNA-X use the same method?Thanks.

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