An advanced beamforming approach based on two-channel echo-train system to cancel interference within an NQR signal resonance spectrum

Interference can be a huge challenge for Nuclear Quadrupole Resonance (NQR) signal detection in real life settings. The problem is particularly challenging when interference is strong around the resonant frequency band of the targeted NQR signal (to which we refer as the NQR band). This paper first proves the beamforming characteristics of a designed two-channel echo-train (TE) data acquisition system, and then presents a novel beamforming approach which is based on the TE system and is able to cancel interference effectively within the NQR band. After interference cancellation, NQR signal detection can be done successfully by applying an ”echo train” approximate maximum likelihood (ETAML) algorithm to the residual data. The proposed algorithm is shown to be superior to previously proposed algorithms, including the classical beamforming algorithms/detectors constructed on the TE system, for detecting NQR signal polluted by interference.