Nuclear quadrupole resonance system and method of using the same to remove interference components from sensor signals
A nuclear quadrupole resonance (NQR) sensor assembly includes an active sensor coil configured to transmit radiofrequency (RF) signals to an object of interest and receive return RF signals from the object of interest to generate sensor signals substantially representative of the return signals. The at least one reference coil is configured to receive environmental RF signals to generate reference signals at least partially representative of the environmental RF signals. The at least one reference coil is co-located with the active sensor coil. The active sensor coil and the at least one reference coil are in communication with a correction unit configured to remove interference components from the sensor signals using the reference signals.
1. A nuclear quadrupole resonance (NQR) sensor assembly comprising:
an active sensor coil configured to transmit radiofrequency (RF) signals to an object of interest and receive return RF signals from the object of interest to generate sensor signals substantially representative of the return signals, said active sensor coil extending in a length-wise dimension and a height-wise dimension orthogonal to the length-wise dimension; and
at least one reference coil extending in the length-wise dimension and the height-wise dimension and separated from said active sensor coil in a depth-wise dimension orthogonal to the length-wise and height-wise dimensions, said at least one reference coil thereby decoupled from said active sensor coil, said at least one reference coil configured to receive environmental RF signals to generate reference signals at least partially representative of the environmental RF signals, wherein the reference signals are used to reduce interference components within the return signals.
2. The NQR sensor assembly in accordance with claim 1 , wherein said at least one reference coil is a plurality of said reference coils co-located with said active sensor coil, wherein said plurality of said reference coils and said active sensor coil are tuned to receive return RF signals within a frequency band defined by at least one resonant frequency of the object of interest.
3. The NQR sensor assembly in accordance with claim 2 , wherein said plurality of reference coils comprises at least one of said reference coils positioned on each of opposite sides of said active sensor coil.
4. The NQR sensor assembly in accordance with claim 2 , wherein said plurality of reference coils are at least partially overlapped a predetermined amount in the length-wise and height-wise dimensions that substantially reduces mutual inductance between said plurality of reference coils.
5. A nuclear quadrupole resonance (NQR) system comprising:
an active sensor coil configured to transmit radiofrequency (RF) signals to an object of interest and receive return RF signals from the object of interest to generate sensor signals substantially representative of the return signals, said active sensor coil extending in a length-wise dimension and a height-wise dimension orthogonal to the length-wise dimension;
at least one reference coil extending in the length-wise dimension and the height-wise dimension and separated from said active sensor coil in a depth-wise dimension orthogonal to the length-wise and height-wise dimensions, said at least one reference coil thereby decoupled from said active sensor coil, said at least one reference coil configured to receive environmental RF signals to generate reference signals at least partially representative of the environmental RF signals; and
a correction unit in communication with said active sensor coil and said at least one reference coil, said correction unit configured to remove interference components from the sensor signal using the at least one reference signal.
6. The NQR system in accordance with claim 5 further comprising a transmit/receive switch configured to shift said active sensor coil between a receive mode of operation and a transmit mode of operation.
7. The NQR system in accordance with claim 5 further comprising an NQR spectrometer configured to transmit pulsed signals to said active sensor coil to facilitate the transmission of the RF signals.
8. The NQR system in accordance with claim 5 , wherein said correction unit is configured to determine a presence of radiofrequency interference (RFI) in the environmental RF signals.
9. The NQR system in accordance with claim 5 , wherein said correction unit is configured to generate a synthesized reference signal at least partially representative of the environmental RF signals and estimated interference parameters.
10. The NQR system in accordance with claim 5 , wherein said at least one reference coil is a plurality of said reference coils co-located with said active sensor coil.
11. The NQR system in accordance with claim 10 , wherein said plurality of reference coils comprises at least one of said reference coils positioned on each of opposite sides of said active sensor coil.
12. The NQR system in accordance with claim 5 , wherein said at least one reference coil and said active sensor coil are tuned to receive return RF signals within a frequency band defined by at least one resonant frequency of the object of interest.
13. The NQR system in accordance with claim 5 , wherein said active sensor coil is configured to be positioned closer to the object of interest than said at least one reference coil such that a sensitive volume is defined proximate the object of interest.
14. A method for performing nuclear quadrupole resonance (NQR) detection, said method comprising:
defining a linear phased-coil array comprising co-locating an active sensor coil with at least one reference coil such that the coils extend in a length-wise dimension and a height-wise dimension orthogonal to the length-wise dimension, wherein the at least one reference coil is separated from the active sensor coil in a depth-wise dimension orthogonal to the length-wise and height-wise dimensions, thereby decoupling the least one reference coil from the active sensor coil;
generating sensor signals from an active sensor coil and reference signals from at least one reference coil;
reducing an interference component of the sensor signals using the reference signals to generate corrected signals; and
determining a presence of a target material based on the corrected signals.
15. The method in accordance with claim 14 , wherein generating sensor signals from the active sensor coil comprises transmitting radiofrequency (RF) signals to the target material and receiving return RF signals from the target material to generate the sensor signals that are substantially representative of the return RF signals.
16. The method in accordance with claim 15 further comprising switching the active sensor coil between a receive mode of operation and a transmit mode of operation through operation of a transmit/receive switch.
17. The method in accordance with claim 14 , wherein generating reference signals from at least one reference coil comprises receiving environmental RF signals to generate the reference signals that are at least partially representative of the environmental RF signals.
18. The method in accordance with claim 14 , wherein reducing an interference component of the sensor signals comprises determining a presence of radiofrequency interference (RFI) in the environmental RF signals.
19. The method in accordance with claim 14 , wherein reducing an interference component of the sensor signals comprises generating synthesized reference signals at least partially representative of the environmental RF signals and estimated interference parameters.
20. The method in accordance with claim 14 , wherein generating reference signals from at least one reference coil comprises receiving environmental RF signals from a plurality of reference coils co-located with the active sensor coil.