Lim Tien Sze

Analysis of slotted waveguide structure using MoM techniques

A number of approaches has been suggested for analyzing the performance of slotted waveguide antenna. In this study, a well-known technique namely, the method of moment (MoM) is used to design slotted waveguide antenna arrays. Two types of slotted waveguide structure namely centerline slot with tuning screw and shunt slot are presented. Generally, the performance of the slotted arrays depends on the choice of physical dimension, slot displacement, number of slots and their overall arrangements. A comparison on their effects using numerical simulation is presented and discussed.

Development of a semi-automated SAR test-bed

Observation of the Earth from aerial and spaceborne platforms using synthetic aperture radar (SAR) has provided scientists and researchers with a deeper knowledge of the physical surface information of the planet. With the aim of launching our own SAR sensor into orbit for the purpose of remote sensing, we have a program to test our systems in an airborne platform. Prior to that, we need to first test all related on-board subsystems of SAR sensor on the ground. A semi-automated rail enabled ground-based SAR imaging test-bed was developed and is able to function carrying our L-band SAR systems. Part of the challenge in this project is the scale, as related L-band SAR system is relatively larger than systems of higher bands. The target and scan area covered in the ground measurement is also large, leading to a rail design that need to be extendable yet still mobile. This paper explains our systems radio frequency (RF) subsystem, which generates, transmits and receives the electromagnetic waves and also the rail-based Positioner Subsystem. In addition, the paper also shows the SAR system design specifications, how they are applied into the RF subsystem, and its implementation with the moving platform of the Positioner Subsystem in a field test.

Kalman Filtering and Its Real‐Time Applications

Kalman filter was pioneered by Rudolf Emil Kalman in 1960, originally designed and developed to solve the navigation problem in Apollo Project. Since then, numerous applications were developed with the implementation of Kalman filter, such as applications in the fields of navigation and computer visions object tracking. Kalman filter consists of two separate processes, namely the prediction process and the measure‐ ment process, which work in a recursive manner. Both processes are modeled by groups of equations in the state space model to achieve optimal estimation outputs. Prior knowledge on the state space model is needed, and it differs between different systems. In this chapter, the authors outlined and explained the fundamental Kalman filtering model in real‐time discrete form and devised two real‐time applications that implement‐ ed Kalman filter. The first application involved using vision camera to perform real‐ time image processing for vehicle tracking, whereas the second application discussed the real‐time Global Positioning System (GPS)‐aided Strapdown Inertial Navigation Unit (SINU) system implementation using Kalman filter. Detail descriptions, model derivations, and results are outlined in both applications.

Abnormal sound analytical surveillance system using microcontroller

Analytical surveillance can perform the surveillance tasks much more efficient comparing to operator manual monitoring. This had made it getting increased markets interest in recent years. Commonly, closed circuit television (CCTV) is used for security surveillance. However, CCTVs are purely vision output. These silent videos may not provide complete picture of the happening. Sound detection is incorporate into vision surveillance for enhancement. Sound detection is able to detect abnormal sound although happen at camera blind spots or due to intentional blocking. In this paper, we propose to use microcontroller embedded system to enhance current CCTV system. Proposed abnormal sound embedded system is to carry out the sound detection, audio processing and analysis. This study is using only single microphone for sound detection. Audio amplitude and frequency range are targeted feature extracted from Fast Fourier Transform (FFT). Abnormal sound of human screaming and glass breaking were classified using decision tree. From experiment, proposed abnormal sound analytical surveillance system test yield average of 88% accuracy detection. We can consider our work is simple and cost effective for field implementation.

Ku-band ground-based SAR experiments for surface deformation monitoring

Continuous monitoring of ground deformation on high-risk areas is of great importance for the study of landslide mechanisms as well as to serve as an early warning system before the triggers of hazardous events. A new ground-based synthetic aperture radar (GBSAR) has been developed and installed at selected landslide-prone areas in Malaysia. The proposed system operates at 17.2 GHz with high resolution change detection capability using interferometry technique. This paper presents the experimental results of the GBSAR in surface deformation monitoring.

Monte-Carlo analysis of a new 6-T full-adder cell for power and propagation delay optimizations in 180 nm process

This paper presents a 1-bit full adder by using as few as six transistors per bit in its design. It is designed with a combination of multiplexing control input and Boolean identities. The proposed design features lower operating voltage, higher computing speed and lower energy consumption due to the efficient operation of 6-transistor adder cell. The design adopts Multiplexing with Control input technique to alleviate the threshold voltage loss problem commonly encountered in pass transistor logic design. The proposed design successfully embeds the buffering circuit in the full adder design and the transistor count is minimized. The improved buffering helps the design operate under lower supply voltage compared with existing works. It also enhances the speed performance of the cascaded operation significantly while maintaining the performance edge in energy consumption. For performance comparison, the proposed full adder is evaluated along with four existing full adders via extensive BSIM4 simulation. The simulation results, 180nm process models, indicate that the proposed design has lowest energy consumption per addition along with the performance edge in both speed and energy consumption makes it suitable for low power and high speed embedded processor applications.

A PC-based orientation sensing using 9-DOF strapdown inertial measurement unit

This paper presents the design and development of a PC-based orientation sensing system using strapdown inertial measurement unit (SIMU). A 9-DOF (degree of freedom) SIMU, which consists of 3-DOF gyroscopes, 3-DOF accelerometers, and 3-DOF magnetometers, are used to estimate the orientation. Data fusion is performed to improve measurement accuracy. In this paper, the orientation measurements are compared and discussed using three different approaches, known as the conventional accelerometer/gyroscope approach, the Kalman filter based 9-DOF SIMU approach, and the gradient decent algorithm based 9-DOF SIMU approach. The derivation of each approach together with the design of the PC-based orientation sensing system is outlined in this paper.

Analysis of novel slotted waveguide structure for antenna arrays application

Summary form only given. A number of approaches have been suggested for analyzing the performance of slotted waveguide antennas. In this study, a well-known technique called the method of moments (MoM) is used to design slotted waveguide antenna arrays. Novel types of slotted waveguide structure namely centerline slot with tuning screw are presented. Generally, the performance of the slotted arrays depends on the choice of physical dimension, width, and displacement of the tuning screw, number of slots and their overall arrangements. The results from the numerical simulation are compared to the widely used finite element code (high frequency structure simulator) HFSS.