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Measurements >> RF Measurements >> Power average vs Log average on Spectrum analyzer
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Message started by iVenky on Dec 18th, 2018, 3:58pm

Title: Power average vs Log average on Spectrum analyzer
Post by iVenky on Dec 18th, 2018, 3:58pm

Hi,

I have a question regarding the average feature on spectrum analyzer.

First thing, why do we need average? What's that that's causing the measurement error to change? if you look at the figure below, we can see that the noise power changes by about 10 dB (between -50 dBm and -60 dBm). Why does this happen? Is it just because the mean square value at the output of IF filter is changing with time because of finite time averaging?

Second question. Which one is accurate or right? Log average or Power average? I can understand Power average. Because log average can give a lower value, I would want to know the reason behind using log average or when it is useful?


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