Interference Cancellation in Two-Channel Nuclear Quadrupole Resonance Measurements

Given its high specificity, the use of nuclear quadrupole resonance (NQR) spectroscopy allows for a reliable identification and quantification of substances containing quadrupolar nuclei, such as the 14N nucleus prevalent in many explosives, medicines, and narcotics. Regrettably, the measured signals are typically weak and suffers from interference signals often being several orders of magnitude stronger than the signal of interest. In this work, we propose a two-channel setup allowing for interference cancellation in applications such as demining. The proposed techniques forms an estimate of the interference using the secondary channel, and then removes it from the primary channel. The improved performance of the resulting detector is illustrated using real measurements of NaNO2.