Frequency-domain characterization of magnetoelastic sensors: a microcontroller-based instrument for spectrum analysis using a threshold-crossing counting technique

This work presents a novel instrumentation technique for frequency-domain characterization of magnetoelastic sensors. By applying threshold-crossing counting to the transient response of a magnetoelastic sensor excited by sinusoidal pulses, frequency-domain analysis is accomplished without the necessity of using lock-in amplifier or FFT facilities as required in the conventional instrumentation techniques. The threshold-crossing counting technique is discussed and its electronic implementation described. The resulting compact and cost-effective microcontroller-based instrument is capable of frequency-domain analysis, and time-domain analysis including frequency counting and determination of the damping ratio.