Select the correct statement$($s$)$ regarding the signal$-$to$-$noise ratio $($SNR$).$

a$.$ SNR represents the unitless ratio of receive power to noise floor power

b$.$ the non$-$decibel form of SNR is: SNR $=$ S $($watts$)$ N $($watts$)$

c$.$ the correct equation for SNR in decibel form is: $[$SNR$]$dB $=[$S$]+[$N$]$

d$.$ all statements are correct