Subject: Priniciples of Communication Engineering

Difficulty : Medium

Marks : 05

Noise factor (f)

It is defined as ratio of signal to noise ratio at the input to signal to noise ratio at the output of the receiver. Ideally value of F is 1 for a receiver. SNR at the input is always higher than SNR at the output hence practically noise factor will be greater than 1.

Noise factor (f) = $\frac{SNR \ at \ the \ input}{SNR \ at \ the \ output}$

Noise figure (NF)

If the noise factor is expressed in decibels then it is called noise figure (NF)

NF = 10 log (Noise Factor)

NF = 10 log $\frac{SNR \ at \ the \ input}{SNR \ at \ the output}$