# Relation between SNR and Eb/No (part 2)

Usually we found in papers or other written sources of data transmission performance in telecommunication system with BER vs Eb/No. Then there is also with BER vs SNR. So which one that we should use?

Actually we can use all of them. It’s depend on our purpose. Eb/No is often used when we want to know how far the performance from the shannon limit boundary. SNR is used when we just want to know the overall signal power, doesn’t care about: how big the bit energy, how far the performance from the shannon limit boundary, using guard interval or not.

Following are the conversion from SNR to Eb/No or vice versa:
$\frac{S}{N} = \frac{Eb}{No} \, R \, M \, \frac{1}{J} \, G$

$\frac{S}{N} [dB] = \frac{Eb}{No} [dB] + 10 log10(R) + 10 log10(M) + 10 log10 (\frac{1}{J}) + 10 log10(G)$

where :
R = bit rate
M = number of bits in each constellation symbol
J = sampling rate
G = guard interval ratio.

## One thought on “Relation between SNR and Eb/No (part 2)”

1. Alex says:

Please provide a reference for the equation you have provided.

Thank you.