Signal-to-Noise Ratio

The signal-to-noise ratio (SNR) compares the level of the input signal to the background noise present at detection.

The following equation defines the signal-to-noise ratio:

SNR = F Σ       P Noise

In the previous equation, SNR is equivalent to the measurement of noise in the presence of a signal.

You can approximate the SNR for signals dominated by a fundamental tone. For these signals, the SNR is high and approximately the inverse of the difference between the total harmonic distortion plus noise (THD+N) and the total harmonic distortion (THD).

SNR ≈ ( ( T H D + N ) 2 − ( T H D ) 2 ) − 1 2