LAUSR

We derive the Cramer-Rao lower bounds (CRBs) for all target parameters associated with noisy measurements of a specific class of targets using a frequency-domain electromagnetic induction (EMI) system. The target parameters include the target tensors, the relaxation frequencies and their corresponding amplitudes, as well as the target location. We validate the derivation through Monte Carlo simulation. We then derive approximate CRB (ACRB) expressions based on a new low-rank model perspective for EMI data. These approximate expressions are significant simplifications over the full CRB expressions. They also facilitate the analysis and improve the understanding of the factors impacting the lower bounds on the target parameters. We demonstrate the utility and accuracy of the ACRB expressions for two example targets.