- Presents the unwanted part of signal – something that was not put there and should not be there.
- THD+N vs. amplitude graph is important as it reveals SNR, dynamic range, and THD+N ratio; all are expressed as ratio compared to a specified signal level.
- The difference between THD+N level and THD+N ratio must be understood.
- Signal level, signal frequency, and measurement bandwidth must be known (or guessed) when analysing results.
- SNR is a ratio of two measurements, level and noise measurements, expressed in dB.
- Signal level, measurement bandwidth, and weighting filter must be defined.
- Dynamic range is like SNR but noise is measured in the presence of small signal; results should be the same.