Spectrum Analyzer

hej, Is there anyone who can answer this question.I am confuesd about my problem.

*** In the Spectrum analyzer it sometimes is impossible to set the input attenuation to lower values (e.g it is not possible to set the attenuator to 0,10,20 dB but higher values are possible) why does this phenomenon occur????

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What spectrum analyzer are you talking about.

Actually there was no mention on this question what type spectrum analyzer is used ?suppose ,Any kind of SPA?

Nowadays I am using ''Handheld Spectrum Analyzer R&S FSH3 ''

Are you talking about attenuation or reference? Or maybe resolution (dB/div) ?

There is one input attenuator internally in the Spectrum Analyzer.I am talking about this internal attenuator.you can manually vary internal attenuator whenever you want to measure the power or whatever?my question,sometimes we can set the internal attenuator at lower value like 0 dB,10 dB or 20 dB but sometimes we have to set the internal attenuator at higer value like 30 dB,40 dB or 50 dB why?

I am using also FSH6 version (SA) .can have relation between source signal and internal attenuator in Spectrum analyzer?I mean ,when you want to inject higer signal at the SA for measuring the power or if you want to inject the small signal at SA input for measurement the power then you have to change the Spectrum Analyzer' input attenuator.every Spectrum analyzer have the internal input attenuator.I am talking about this attenuator.please if you have any more answers try to drop here ..........


thank

MSc in Telecommunication Engr.
sweden