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Use QspectrumAnalyzer to analyze signal,set sample rate as 8M and 32M.
I get different output as below,32M sample rate cause burst signals disappeared.
enter image description here

enter image description here

enter image description here What make sample rate affect QspectrumAnalyzer output?

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  • $\begingroup$ What is the bandwidth of your signal? $\endgroup$
    – Gillespie
    May 19, 2022 at 20:43
  • $\begingroup$ @Gillespie,bandwidth sets to 0 in Qspectrumanalyzer. $\endgroup$
    – kittygirl
    May 19, 2022 at 21:23
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    $\begingroup$ But what is the bandwidth of the underlying signal you are trying to measure? That will tell you what sampling rate you need to use to avoid aliasing. Check out these links to see the relationship between signal bandwidth and sampling requirements: - thewolfsound.com/… - en.wikipedia.org/wiki/Aliasing $\endgroup$
    – Gillespie
    May 19, 2022 at 21:49
  • $\begingroup$ @Gillespie,Qspectrumanalyzer will automatically set bandwidth when bandwidth is 0 $\endgroup$
    – kittygirl
    May 19, 2022 at 22:49

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It's not entirely clear from your question, but if the bandwidth of your signal is higher than your sampling rate, you will get aliasing, causing the spectrum to look different. So perhaps 8 MHz isn't a high enough sample rate for your signal.

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  • $\begingroup$ I set bandwidth to 0 in Qspectrumanalyzer,which means software will crop and combine fft result based on the sample rate. $\endgroup$
    – kittygirl
    May 19, 2022 at 21:22
  • $\begingroup$ @kittygirl as Gillespie pointed out, it's not about the bandwidth that you set for your visualization, but the bandwidth that your signal has. Two different things. $\endgroup$ May 20, 2022 at 9:12
  • $\begingroup$ @MarcusMüller,the signal bandwidth is 80M,is 32M sample rate enough in Qspectrumanalyzer? $\endgroup$
    – kittygirl
    May 20, 2022 at 21:58
  • $\begingroup$ @kittygirl if your signal bandwidth is really 80 MHz, 32 MHz will not be enough. Read the articles I linked to and you will understand this. I suggest you also read some documentation on Qspectrumanalyzer to understand its settings better. $\endgroup$
    – Gillespie
    May 20, 2022 at 22:34
  • $\begingroup$ @Gillespie kittygirl really has worked with FFTs and spectra for a while: I'm sure reminding them of Nyquist is enough! $\endgroup$ May 21, 2022 at 19:06

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