| 1. |
- Aldhubaib, F., et al.
(författare)
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Aspect segmentation and feature selection of radar targets based on average probability of error
- 2010
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Ingår i: IET Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 4:10, s. 1654-1664
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Tidskriftsartikel (refereegranskat)abstract
- Through statistical estimation by a non-parametric model, a fused polarimetric and resonant return from the radar target is modelled as a function of the target aspect angle. The outcome of this type of modelling is a set of non-parametric density estimates, which are then used to represent this target in a multi-dimensional probability space. These densities within this probability space can be well separated and therefore utilised to make decision rules to identify targets of interest. The return set to be modelled is the average power set associated with spectral bands centred on the target natural resonant frequencies. This return set is mapped into density set using a Gaussian kernel function; subsequently, the density set will be considered as the target radar feature set of interest. To decrease density overlapping between respective densities of different targets, a criterion based on the Bayesian error is employed; first, to bisect the aspect global range into smaller sectors, and second, to select discriminative features that can minimise the average probability of error between the targets respective features. The results show that two targets with similar resonant frequencies can be separated by the Bayesian error criterion based on the proposed features. A simple likelihood ratio test had more than 80% success down to 20 dB of signal-to-noise ratio.
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| 2. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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A Novel, Fast, Approximate Target Detection Technique for Metallic Target Below a Frequency Dependant Lossy Halfspace
- 2010
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 58:5, s. 1699-1710
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Tidskriftsartikel (refereegranskat)abstract
- The extinction pulse (E-Pulse) technique has been widely applied to problems involving radar target identification. In this paper a fast approximate target detection and recognition scheme based on the E-Pulse technique is proposed and applied to a subsurface target detection and recognition scenario. Previous studies have demonstrated that the target resonances for subsurface targets are closely related to the target resonances for a target within a homogenous environment. In the proposed method, the target resonance for the target in the homogenous medium will be used to construct the E-Pulse for target detection and recognition purposes. The details of the proposed method will be described in this paper. The obvious example of a target below a dielectric halfspace is the use of ground penetrating radar (GPR) for detecting and recognizing unexploded ordnance (UXO). However, instead of a GPR related scenario, a numerical example of a biomedically related problem, of a hip prosthesis model sited within a halfspace of homogenous human tissue model with realistic dielectric properties will be used to demonstrate the feasibilities of the proposed technique for target detection and recognition. The reasons for the choice of this particular example will also be explained in the paper.
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| 3. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Joint Time-Frequency Analysis of Transient Electromagnetic Scattering from a Subsurface Target
- 2012
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Ingår i: IEEE Antennas and Propagation Magazine. - 1045-9243. ; 54:5, s. 109-130
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Tidskriftsartikel (refereegranskat)abstract
- The complexity of transient electromagnetic scattering from objects in free space has been well known for years. Such complexity is mainly due to the high aspect dependency of the early-time response, and the interactions between the various scattering events. Attempts have been made to analytically and numerically study the transient scattering problem using time-frequency (TF) analysis. Using this technique, the occurrences of the scattering events and their frequency content can be revealed, which leads to further information about the actual scattering behavior. For the case of subsurface targets, the entire problem becomes more complicated with the introduction of a dielectric interface. Analytical solutions of such complicated electromagnetic problems are usually not available, and can only be numerically addressed in most cases. In this paper, a systematic study of transient scattering from some subsurface targets is presented. The various interactions between the target and the interface of the half-space can be clearly observed. The findings from this work have opened up some issues that are left for further investigation.
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| 4. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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On the modelling of transient scattering under ultra wideband short-pulse electromagnetic excitation
- 2010
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Ingår i: 2010 Asia-Pacific Symposium on Electromagnetic Compatibility, APEMC 2010. - 9781424456215 ; , s. 854-857
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Konferensbidrag (refereegranskat)abstract
- Accurate modelling of electromagnetic radiation, scattering and propagation using ultra wideband (UWB) sources has been of significant interest with ongoing application in areas such as short-range communications, through-the-wall imaging, ground-penetrating radar and medical imaging etc. Numerical modelling of these applications is vital to the evaluation and enhancement of their performance In this paper, a review of different methods for numerical modelling of the transient electromagnetic response under UWB short-pulse excitation is undertaken. The advantages, limitations and challenges of both direct and indirect time domain methods are described in detail and numerical examples of transient scattering demonstrate the use of an indirect time domain method.
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| 5. |
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| 6. |
- Lui, Hoi-Shun, 1980, et al.
(författare)
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Resonance Based Target Recognition Using Ultra-Wideband Polarimetric Signatures
- 2012
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Ingår i: IEEE Antennas and Propagation Magazine. - 1045-9243. ; 60:8, s. 3985-3988
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Tidskriftsartikel (refereegranskat)abstract
- Automated target recognition based on resonances embedded in the ultrawideband transient signatures has been of significant research interest throughout the years. In most studies, targets are usually illuminated and measured using a linear polarized basis. This could lead to an incorrect result for target recognition as some resonant modes may not be well excited at that particular incident aspect and polarization state. In this communication, the possibility of using a full-polarimetric ultrawideband target signature is investigated. Target recognition of some simple wire targets using the extinction pulse technique demonstrate that it would be easier to fully excite all of the important resonances using a circular polarization basis with due consideration of the co- and cross-polarized target signatures.
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