Design of Thermal Noise Thermometry Using Cross-correlation Method

Aiming at the problem that the existence of interference noise affects the measurement accuracy in the process of temperature measurement using the resistor thermal noise signal, a method of using a digital correlator to eliminate interference noise is proposed, which is called cross-correlation method. Two symmetrical signal processing channels are designed to ensure that the output signals of the two channels are the superposition of the same input signal and the interference signals generated by the two channels respectively. Then the acquisition card is used to synchronously collect the output signals of the two channels and convert them into digital signals. Finally, the cross-correlation calculation of the two signals is realized by the digital correlator program, which effectively reduces the influence of the major interference noise. The experimental results show that the thermodynamic temperature measurement with a relative error of 0.51% is realized at room temperature by the method proposed, which proves the effectiveness of the system.