Type K thermocouples have three levels of accuracy: Level I: Measurement range 0-1000°C, error 1.5°C, representing 0.4% of the measured temperature. Figure i shows the system hardware block diagram. Material performance specifications for K-type thermocouple: Positive grade is nickel-silicon, negative grade is nickel-aluminum, with melting points of 1427°C and 1399°C, respectively. Resistivity (at 0°C) is 70.6 D/cni for the positive grade and 29.4 nD/cni for the negative grade. Thermal expansion coefficients are 13.1 x 10^-6, and thermal conductivities at this coefficient are 655 MPa and 586 MPa, respectively. Due to the low output sensitivity of thermocouples, with only a few tens of pV of voltage output per degree, the temperature drift of the amplification circuit must be very small. Additionally, thermocouples all have non-linear errors, requiring a non-linear correction circuit. Cold junction compensation also needs to be considered.