Noise measument in S.A noob problem

Hi !

On the analyzer i think i see the - 174dBm + 10log(RBW) + NF of S.A

for RBW=1KHz and NF of S.A = 30dB ..Noise Input (analyzer with input at


I think this is what i see in the display screen. Maye there is some also -( 2-3 dB) of noise that the Sample dETector adds..

Also i think the real display BW is 1.2*RBW ,because of gauss IF filter's shape

Is this right? :grin:

So today i did a simple experiment with an LNA . I saw that the output noice power was not input +GAIN + NF .... i don't know why this...

I think we must think the system as a cascade.

---LNA with NF1,G1 ---- S.A NF2,G2---display

So Noiceout=-174dBm+10logRBW+NFtotal+Gtotal..

This will show as the noice floor ..

But what is the Gain of S.A?