Active Q-damping sub-system using nuclear quadrupole resonance and nuclear magnetic resonance for improved contraband detection
US6291994A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 14, 2000 |
| Grant date | Sep 18, 2001 |
| Priority date | — |
| Expiry date | Jan 14, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N24/084
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A Q-damping subsystem for either an NQR or NMR contraband detection receiver for effectively reducing the dead time and increasing sensitivity of the contraband detection system. The invention acts as an addition to the standard transmit circuits of NQR and NMR based scanners and spectrometers. The active Q-damping devices require additional circuitry for an NQR/NMR detection receiver and a programming for the control thereof. Typically, the detection receiver generates a high-voltage RF pulse on the order of 200-1000 V with normal operation of 100-300 microseconds in length to provide sufficient magnetic field characteristics to perturb the precessing nuclei. The NQR or NMR detection receiver electronics are very sensitive and have to detect a very weak nuclear induction pulse signal that is in the nano/micro-volt range. The invention encompasses several embodiments of the detection receiver with the Q-damping subsystem which include: a transformer coupled resistive damping circuit; an inductively coupled resistive damping circuit; a shunt capacitor/resistor damping circuit; a grounded shunt capacitor/resistor damping circuit; a common mode choke transient suppression damping circ…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.