1. Terminology relating to the qualities of a measurement chain

Fidelity is the most important quality of any measuring instrument. A non-fidelity device is not a measuring device. Fidelity is the ability to give reproducibly, under defined conditions of use, very similar responses when the same input signal is applied repeatedly. Independently of accuracy, the fidelity error describes the dispersion of measurements of the same temperature over a series of experiments. It results from various errors, linked to mobility, hysteresis, readout or even background noise when sensitivity is too high. If the influencing variables linked to the measurement conditions are poorly controlled, we will be forced to consider their effects as part of the fidelity error.

The sensitivity of a measurement chain is the quotient of the increase in its response G by the corresponding increase...