Application of an FFT-based algorithm to signal processing of LVDT position sensors

This paper presents a new method for signal processing of Linear Variable Differential Transformer (LVDT) position sensors. The method, based on a spectral estimation of the differential secondary signal, has been implemented using a floating point Digital Signal Processor (DSP) and a fourteen-bit Analog Interface Circuit (AIC) to generate the primary signal and to process the primary and the secondary signals. The resulting accuracy improves if compared with the classic solution based on synchronous demodulation. Also, the lack of need of heavy filtering, except for the antialiasing function, can decrease the measuring time and offers diagnostic capability