Noise floor measurment

[tyles88]

Hi Guys!

Im hoping someone can clear up a problem I am having. I am doing some measurements using a spectrum analyser and am having some problems understanding how i can calculate the noise floor.

I understand that this needs to be done at a given frequency?

From what I have read the value seems to change with lots of external factors!

So can I just reed the value of of the spectrum analyser with no load and thats that value I'm looking for?

Sorry if my questions seem stupid I'm really confused lol!

 

[Joel-Tang]

Well if you want to know the noise performance of the analyzer for a 50-ohm use case I would suggest measuring noise into 50 ohms.
Here you will find the calculation for thermal noise for a given Bandwidth, resistance, and temperature.
In the case of the spectrum analyzer your Resolution Bandwidth is your bandwidth. Whatever you measure above and beyond the thermal noise equation is due to the Analyzers contribution.

I think this is what you where looking for.

I hope this helps.