  The influence of temperature is a major problem in Structural Health
Monitoring diagnosis using guided waves. In this article, two methods for
temperature compensation are used to evaluate the temperature of a structure
monitored by Piezoceramic Transducers (PZT). The first one consists in a linear
regression of the static capacity of the PZT (computed with the
electromechanical impedance) with the temperature. It allows one to determine
temperature of a PZT from any impedance measurement. The second method is based
on the Modes Frequency Shift (MFS) of the frequency response function (FRF)
calculated in a pitch-catch mode with an exponential sweep signal. A linear
regression between the MFS and the temperature is settled for most modes and
allow the estimation of temperature between two PZT. Experiments on a composite
plate monitored by 5 PZT patches showed that a $\pm$2{\textdegree}C degree
variation can easily be identified with both methods. Combined together, those
two methods could replace actual temperature sensors and bring an efficient
improvement for temperature compensation in applications where the temperature
variation is heterogeneous on a structure.
