Comparison of Signal Processing Algorithms for High-Resolution FMCW Terahertz Thickness Measurements

When using the frequency-modulated continuous-wave (FMCW) approach for layer thickness determination of dielectrics, such as multilayer pipe walls, the resolution is usually limited by the bandwidth. For thinner layers, we compare the measurement signal with potential model signal outputs. Since our approach results in high computation efforts by using brute force optimization, spectral estimation may present an alternative for high resolution distance and hence thickness determination. In this contribution, we compare results of a parametric algorithm (modified covariance method) and a subspace method (multiple signal classification, MUSIC) with the results of our approach.