Patent ID: 9476953
Filing Date: 2016-10-25
CPC Classification: G01N,G01R

Claim Text:
1. A Nuclear Quadrupole Resonance (NQR) measurement system for detecting at least one material under test (MUT), the system comprising: a waveform generator configured to generate a continuous wave (CW) input signal comprising one or more frequencies; a chamber configured to receive the at least one MUT when carried by a person passing through the chamber; a probe configured to excite the MUT and then detect NQR RF emissions from the MUT; a bridge circuit configured to subtract a signal representing the CW input signal in the chamber from a response signal that includes the CW input signal and the NQR RF emissions to generate output NQR RF emissions; a detector configured to detect the MUT based, at least in part, on the NQR RF emissions; and a signal generator configured to generate the CW input signal; wherein the bridge circuit further comprises: a reference impedance; and a resistor connected between the signal generator and the reference impedance, wherein the signal representing the CW input signal is generated at a node between the signal generator and the reference impedance.