Resonance-Frequency Tracking System Based on a Software-Defined Radio Platform

Resonator-based sensors are generally employed in measurement systems to indirectly infer a large number of physical quantities through their resonance frequency. One efficient approach for dynamically tracking the resonance frequency is the use of phase-locked loop (PLL)-based techniques. This work implements a resonance frequency tracking routine in LabVIEW using a software-defined radio (SDR) platform chosen due to its wide operation frequency availability and flexibility in testing different control strategies. A theoretical and simulation model of the resonance frequency tracking system is proposed. To validate the system experimentally, a resonant cavity is used. The results show that the system was able to properly track the resonance frequency of the cavity after a controlled perturbation. A high correlation with the simulated results based on the theoretical model is also observed. In addition, a phase-reference tracking experiment was also demonstrated. Both experiments combined demonstrate that an SDR can be used to develop efficient and relatively low-cost real-time resonator-based sensors for different applications.