# High SNR value unacceptable

I am stuck in a situation here while calculating received SNR in AWGN channel.

When I performed calculations directly in decibels, I got very high SNR value for instance 140 dB.

I am using the formula:

SNRreceived = [power transmitted(dBm) + FSPL(dB)]-[No(db) * B(hz) + 10log(KT) + NF(dB)]

Could anyone point out where am I mistaken or my formula is not correct?

• You can't multiply the value of $N_0$ in decibels by the bandwidth $B$ to get the noise power; you need to compute $N_0B$, not $[10\log_{10}(N_0)]B$. – Dilip Sarwate Mar 3 '14 at 4:05
• @DilipSarwate You should make that an answer. – Jim Clay Mar 3 '14 at 12:50
• @JimClay There are too many other errors in the OP's formula (e.g. adding NF (noise floor? noise figure?) expressed in dB to other terms also expressed in dB) that a full answer will take a lot more time to write. – Dilip Sarwate Mar 3 '14 at 14:24