Thermoelectrically generated noise in sheathed thermocouples and in other low level instrumentation cables

Starting from the fact that emfs of thermocouples are generated in the thermal gradients and not at the hot junctions, it is shown how thermoelectric heterogeneity in conjunction with natural and forced convection phenomena gives rise to unwanted noise called "thermoelectrically generated noise" or briefly "thermoelectric noise" if it is agreed to take this expression in its technological sense. The reported experimental results confirm that noise amplitudes can be embarrassing when dealing with problems of quantitative signal fluctuation analysis. It is however emphasized that thermoelectric noise can also convey useful information which, without noise, could be lost.