Signal to Noise and Distortion (SINAD) is a parameter with which a statement can be made about the signal quality of audio and RF signals. Receivers, digitizers and other equipment can be evaluated using the measurement technique relevant to Sinad.
By definition, Sinad is the ratio of total signal power, including noise and that from distortion, to that from noise with distortion. The total power is composed of the signal power (S) plus the noise power (N) plus the noise power (D), this is related to the noise power (N) plus the noise power (D): thus `(S+N+D) / (N+D), expressed in decibels( dB), `10log * (S+N+D)/(N+D)`. From this relation it follows that the higher the sinad value, the better the signal quality of the output signal.
From the Sinad value, the ENOB value, Effective Number of Bits (ENOB), can be calculated.