#### crazyboy

##### Newbie level 6

I doing a simple receiver noise power calculation. The system consists of an antenna with Low noise amplifier and subsequent attenuation and gain stages.There are no mixing stages. I managed to find out the equivalent Noise Figure(NF) of entire system using Friss-Noise figure formula and arrived a value of 9dB.

Calculating the receiver Noise power using the formula Pr = NF*k*T*G I'm getting a Noise floor around -120 dBm/Hz.

Here's are my doubt's:

1. Is the inclusion of G (Gain of chain) is valid ? because in some articles they didn't mentioned about it.

2. Also if its inclusion is valid, then I have to sum up the gain of attenuators (in chain) as well ? or simply the gains of amplifiers only ?

The above calculation which i did is treating the attenuation of attenuator with negative gain and summing up all the gains in system chain. If I omit the gain summation of attenuators I'm arriving at a value of -74 dBm/Hz. So which value I have to consider as the Noise Floor of my system ?

3. The final stage of system is connected to an analyzer. So if i want to find out the minimum detectable power, I have to multiply one of above values with Noise Bandwidth Pr(min) = NF*k*T*G*B Watts. So my another question is which band width I have to consider here? whether it is the RBW / VBW of Analyser or I have to calculate the cascaded -3dB bandwidth of receiver chain?