High-Resolution and High-Precision Demodulation Method for Surface Acoustic wave temperature sensor Based on PRONY algorithm

Because echo signal energy of the resonant wireless and passive surface acoustic wave (SAW) sensor is weak and exponentially decays over time, the frequency resolution of the traditional FFT-based demodulation algorithm is relatively low. Additionally, SAW echo signals are susceptible to environmental noise interference during wireless transmission, significantly impacting the accuracy of traditional demodulation algorithms. To improve demodulation resolution and accuracy of sensor, this study proposes a novel signal processing algorithm based on the PRONY algorithm. The algorithm successfully transforms the high-order difference equations of PRONY algorithm into first-order matrix difference equations, avoiding the potential ill-conditioning problem and round-off error associated with high-order polynomial root-finding. Simulation and experimental results demonstrate that the proposed algorithm achieves high-resolution and high-precision demodulation of SAW echo signals compared to traditional methods. The proposed algorithm is integrated with the developed SAW temperature measurement hard system, the experimental results reveal that within the temperature range of -20~100°C, the system can achieve high-precision temperature measurement of ±0.3°C,while maintaining excellent temperature resolution below 0.0566°C, and achieve maximum distance is up to 2m.