Dear All,
i would like to understand SNR required for PAM4 as well as RZ Receiver, i know for NRZ system it is more or less Q^2, but how to obtain for Pam4. In Broadband circuits for optical fiber communication book by Sackinger he has given but i didn't understand, can any one help me. In page number 364 problem 4.6(a) you can find the explanation.

Thanks,
Raj.