Study on Weak Signal Detecting Technology in High-Temperature Superconducting Resistance Measurement

For detecting the critical transition temperature of the high-temperature superconducting material, a system using a weak signal detection approach - lock-in amplifier to acquire the R-T signals under strong noises, is constructed. The article introduces the principle of the system and focuses on the design of the whole system. The chip-AD630 from the AD company is the core component of the whole system - analog multiplier and the software-programmable V/F converter chip- AD650 also from the AD company is the A/D component of the system. The system achieves the acquisition of weak resistance signal through the well-designed lock-in amplifier. And the system acquires the temperature of the high-temperature superconducting material through the copper-constantan thermocouple, so it achieves the acquisition of the R-T(Resistance-Temperature) signals and then transmits the two-way signals to the PC through the serial port for the use of LabVIEW for the follow-up processing and display. The actual operation shows that this system can accurately detect the critical transition temperature of the high-temperature superconducting material.