Step-wise change in level of signal/noise in R&S spectrum analyzer

noori.re

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Hello every one,

I use an specturm analyzer of R&S. in the spectrum at 5 GHz and 8 GHz I see in change in level of Noise/signal like a step. I checked the trancducer settings. it is not related to the trnacducer settings.
Does someone know how can I reslove this?
Strat freq: 2 GHz
Stop freq: 12 GHz
Res BW: 1MHz
 

Give more information, model number and a screen shot of the display.
It is likely that it is the analyser changing IF gain to compensate for the change in gain when the mixer input frequency range changes. this keeps the reference level constant, but changes the noise floor. This range switching behaviour is very common.
 

It is a range changing artifact, to cover such a wide frequency range the analyser has to change the local oscillator and possibly use harmonic mixing. The IF gain needs to be increased to compensate for increased loss so that the reference level remains constant. It is nothing to worry about. The sudden change at exactly a 1GHz multiple is a give away.
 

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