• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.11
• /
• pp.40-46
• /
• 2014

We introduce a parameter estimation algorithm by using pole-zero coefficients of Pade approximation for radar active cancellation. Proposed scheme is based on relation among pole-zero coefficients of Pade approximation, parameters, and samples of received signal. A closed form solution for parameter estimation is achieved with a few samples of received signal and a simple comparison. Also, stepwise estimation algorithm is proposed to suppress beat effect which is occurred by active cancellation over long time with imperfectly estimated parameters. Simulation results show that proposed scheme performs faster radar active cancellation with lower computational complexity than the conventional schemes.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.11
• /
• pp.903-910
• /
• 2020

This paper introduces a simulator to assess the impacts of the wind and the airframe vibration on the performance of the Active Electronically Scanned Array (AESA) radar mounted in an aircraft. The AESA radar is mounted on the nose cone of an aircraft, and vibration occurs due to the drag force. This vibration affects the behavior of the AESA radar and can cause phase errors in signal. The simulator adopts the geometric model for nose cone, the mathematical models on the rigid-body dynamics of the aircraft, the average/turbulent winds, and the mode/ambient vibrations to compute the position and the attitude of the radar accurately. Numerical studies reflecting a set of test scenarios were conducted to demonstrate the effectiveness of the developed simulator.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.8
• /
• pp.1752-1758
• /
• 2010

A FM-CW radar is used for the various purposes as a remote sensing device since it has the advantages of the relatively simple implementation and the low probability of signal interception. A FM-CW radar uses the same frequency modulated continuous wave for both transmission and demodulation. Therefore, the received beat frequency represents the range and Doppler information of targets. However, using the conventional FFT method, the degree of accuracy and resolution in the spectrum estimation can be seriously degraded in the detection and tracking of fast moving targets because of the short dwell time. Therefore, in this paper, the model parameter estimation methods called as an autoregressive method is applied to overcome these problems and showed that the improved accuracy and resolution can be obtained for the target range and velocity estimation.

• Journal of the Korea Society for Simulation
• /
• v.27 no.4
• /
• pp.61-68
• /
• 2018

This paper deals with ground clutter model for FOD (foreign object debris) surveillance FMCW (frequency modulated continuous waveform) radar. In the FOD surveillance radar, it has received not only the signals reflected by FOD, but also the clutters of the surface of the runway and the grassland simultaneously. However, to detect the FOD, the clutter rejection algorithm is necessary because the RCS (radar cross section) of FOD is nearly same to RCS of the grassland. In addition, it is difficult to apply the MTI (moving target indicator) algorithm as the clutter rejection algorithm because both the FOD and the clutter coexist stationarily. Hence, to remove the stationary clutter, it is crucial to accurately generate clutter map considering the surface of road. In this paper, in order to generate the clutter map, the respective beat signal at every range bin is generated in the case of only the surface without FOD, and then the beat signal accumulated 100 times. And also, Weibull distribution is applied to the RCS value to take the scattering distribution of clutter into consideration. The simulation results show that FOD can be well detected by applying the generated clutter map to the FOD FMCW radar.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.12
• /
• pp.1205-1214
• /
• 2013

Recently spaceborne SAR systems are increasing image resolution and frequency. As a high quality image resolution, the wider bandwidth is required and a wideband signal generator with RF component is very complicated and RF impairments of device is increased. Therefore, it is very important to improve performance by reducing these errors. In this study, the transmission signal of the wideband signal generator is applied to the phase noise, IQ imbalance, ripple gain, nonlinear model of high power amplifier. And we define possible structures of wideband signal generator and measure the PSLR and ISLR for the performance assesment. Also, we extract error of the amplitude and phase from the waveform and use a quadratic polynomial curve fitting and examine the performance change due to nonlinear device. Finally, we apply a high power amplifier predistortion method for non-linear error compensation. And we confirm that distortion in the output of the amplifier by intermodulation component is decreased by 15 dB.

• Proceedings of KOSOMES biannual meeting
• /
• 2003.05a
• /
• pp.125-134
• /
• 2003

This paper describes on the design of Passive-type Radar Reflector for small Ship (PRR-S) based on the newly revised 2000 SOLAS regulations. The design idea, adopted in the study, is to hold PRR-S in the proper ‘catch rain’ position to avoid fluctuations of Radar Cross Section (RCS) due to ship's heeling. The PRR-S consists of octahedral-type radar reflector with circular plates and three-axis gimbaled stabilizer with weight on the bottom of outer gimbal ring. Performance test for the PRR is carried out in an anechoic chamber. The test results show that the reflected radar signal from PRR-S is more uniformly distributed than the reference model (Davis Echomaster).

• Journal of the Korean Geotechnical Society
• /
• v.37 no.9
• /
• pp.13-24
• /
• 2021

Recently, attempts have been made to detect fouling patterns in the ground using Ground Penetrating Radar (GPR) during the maintenance of gravel ballast railway tracks. However, dealing with GPR signal data obtained with a large amount of noise in a site where complex ground conditions are mixed, often depends on the experience of experts, and there are many difficulties in precise analysis. Therefore, in this study, a numerical modeling technique that can quantitatively simulate the GPR signal characteristics according to the degree of fouling of the gravel ballast material was proposed using python-based open-source code gprMax and RSA (Random sequential Absorption) algorithm. To confirm the accuracy of the simulation model, model tests were manufactured and the results were compared to each other. In addition, the identification of the fouling layer in the model test and analysis by various test conditions was evaluated and the results were analyzed.

• Journal of IKEEE
• /
• v.24 no.4
• /
• pp.1034-1038
• /
• 2020

In order to effectively process target recognition using radar, accurate signal information for the target is required. However, such a target signal is usually mixed with noise, and this part of the study is continuously carried out. Especially, image processing, target signal processing and target recognition for the target are examples. Since the field of target recognition is important from a military point of view, this paper carried out research on target recognition of aircraft using a tree-structured fuzzy neural networks. Fuzzy neural networks are learned by using reflected signal data for an aircraft to optimize the model, and then test data for the target are used for the optimized model to perform an experiment on target recognition. The effectiveness of the proposed method is verified by the simulation results.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.9
• /
• pp.898-903
• /
• 2008

In most cases, the trajectory of a ballistic missile is well explained by the Kepler's laws. It implies that the remaining trajectory of the ballistic missile including its final destination can be easily predicted if the position and velocity vector of the ballistic missile at any point on its path can be exactly known. Hence, an effective tracking algorithm based on an exact radar measurement model is very important for developing Ballistic Missile Defense(BMD) system. In this paper, we address to design a nonlinear filter, Unscented Kalman Filter(UKF), to track the ballistic missile.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10b
• /
• pp.761-766
• /
• 1998

GPR(Ground Penetrating Radar) designed with a digital-based signal processing technology utilizes to identify very easily the location, the thickness and the level of either an underground embedment or an underground structure. Prior to use of this GPR equipment on pavement of about 15cm thick, the equipment should foremost be calibrated on a known sample under known condition. The purpose of this study is to verify the applicability of the GPR equipment to a model pavement of about 15cm thick. As part of this effort, the general approach of this study is to verify the applicability of the GPR equipment by various thickness levels and its error ranges thru a statistical analysis.