Measuring Temperature with a Thermocouple

A thermocouple is created when two dissimilar metals touch, and the contact point produces a small open-circuit voltage that corresponds to temperature. Thermocouple measurements require sensing of the cold-junction temperature where the thermocouple wire is connected to the measurement system. Therefore, signal connection accessories should include an accurate cold-junction sensor, and should be designed to minimize any temperature gradients between the cold-junction sensor and thermocouple wire connections.

Other signal conditioning requirements include amplification and filtering, because thermocouples generate low-voltage signals and are susceptible to noise. Your system must also perform linearization through hardware or software because the output voltage is not linear with temperature.