• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.9
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• pp.952-958
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• 2014

In this paper, we propose a parametric sparse recovery algorithm(SRA) applied to a radar signal model, based on the compressive sensing(CS), for the ISAR(Inverse Synthetic Aperture Radar) image reconstruction from an incomplete radar-cross-section(RCS) data and for the estimation of rotation rate of a target. As the SRA, the iteratively-reweighted-least-square(IRLS) is combined with the radar signal model including chirp components with unknown chirp rate in the cross-range direction. In addition, the particle swarm optimization(PSO) technique is considered for searching correct parameters related to the rotation rate. Therefore, the parametric SRA based on the IRLS can reconstruct ISAR image and estimate the rotation rate of a target efficiently, although there exists missing data in observed RCS data samples. The performance of the proposed method in terms of image entropy is also compared with that of the traditional interpolation methods for the incomplete RCS data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1109-1115
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• 2010

FMCW(Frequency Modulation Continuous Wave) Radar can detect the distance and the velocity of forward obstacles using linearly modulated FM signal. For better performance, the RF of radar should be operated with wideband frequency linearity on 300 MHz bandwidth at 77 GHz carrier frequency. In this paper, we propose a simple method for improving frequency linearity of FMCW radar implemented with VCO. The proposed method shows that the Voltage-Frequency relation of VCO could be measured by using the modified Tx waveform of FMCW radar. Then the measured nonlinearity could be compensated using LUT(Look-up Table) with easy. It is noted that the proposed can be adopted in existing system without extra circuit.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.5
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• pp.590-597
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• 2016

We designed the multiple scattering points generation system to simulate an actual situation of target signal for high range resolution radar system. This provides replicating the target signals and controlling the status of target signals for radar system. This is composed transmit antenna and multi target generator. Transmit antenna is waveguide array antenna and multi target generator has signal distribution module and control & power module. Multi target generator is able to provide the high isolation and variable output power. Moreover, in order to monitor all output signals of the multi target generator, the flows of signals are programed in control & power module. The performance is demonstrated using experimented results of high range resolution radar.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.2
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• pp.106-112
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• 2012

Smart Highway is the intelligent highway that improves a traffic safety, reduces incidence of traffic accidents, and supports intelligent and convenient driving environment so that drivers can drive at high speeds in safety[1]. In order to implement the highway, it is required to gather a dangerous data such as obstacle, wild animal, disabled car, etc. To provide the situation information of the highway, it has been gathered traffic information using various sensors. However, this technique has problems such as the problems of various information gathering, lack of accuracy depending on weather conditions and limitation of maintenance. Therefore, in order to provide safe driving information to driver by gathering dangerous condition, radar system is needed. In this paper, we used a developing 34.5GHz RWR(Road Watch Radar) radar for gathering dangerous information and we verified performance of obstacle detecting and resolution through field test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.1-6
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• 2018

This study examined the quality improvement of printed circuit boards (PCBs) in relation to the power consumption for radar. The radar examined is currently in production and being used by the military. The PCB converts 28 V DC to 5 V DC but frequently malfunctions. Therefore, cause analysis was carried out. As a result, the power consumed by a certain communication IC was very high, and the heat generated by the high power consumption caused damage to the surrounding parts. Accordingly, it was changed to an improved communication IC that meets all the radar system specifications. System tests were carried out for the changed communication IC to check the impact on the system, and environmental tests were performed, which proved that the performance required by the radar system is satisfactory. As a result of this improvement, there has been no history of failure in this PCB so far. Therefore, the quality of this PCB has been improved.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.5
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• pp.619-627
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• 2021

Recent advance in low cost and light-weight drones has extended their application areas in both military and private sectors. Accordingly surveillance program against unfriendly drones has become an important issue. Drone detection and classification technique has long been emphasized in order to prevent attacks or accidents by commercial drones in urban areas. Most commercial drones have small sizes and low reflection and hence typical sensors that use acoustic, infrared, or radar signals exhibit limited performances. Recently, artificial intelligence algorithm has been actively exploited to enhance radar image identification performance. In this paper, we adopt machined learning algorithm for high resolution radar imaging in drone detection and classification applications. For this purpose, simulation is carried out against commercial drone models and compared with experimental data obtained through high resolution radar field test.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.501-504
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• 2000

The classical image reconstruction for stripmap SAR is the range-Doppler imaging. However, when the spotlight SAR system was envisioned, range-Bowler imaging fumed out to fail rapidly in this SAR imaging modality. What is referred to as polar format processing, which is based on the plane wave approximation, was introduced for imaging from spotlight SAR data. This paper has been studied for the raw data processing schemes in the spotlight-mode synthetic aperture radar. we apply the wavefront reconstruction scheme that does not utilize the approximation in spotlight-mode SAR imaging modelity, and compare the performance of target imaging with the polar format inversion scheme.

• Journal of electromagnetic engineering and science
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• v.17 no.3
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• pp.113-119
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• 2017

The application of compressive sensing (CS) to a radar imaging system based on a frequency-scanned microstrip leaky wave antenna is investigated. First, an analytical model of the system matrix is formulated as the basis for the inversion algorithm. Then, $L_1-norm$ minimization is applied to the inverse problem to generate a range-azimuth image of the scene. Because of the antenna length, the near-field effect is considered in the CS formulation to properly image close-in targets. The resolving capability of the combined frequency-scanned antenna and CS processing is examined and compared to results based on the short-time Fourier transform and the pseudo-inverse. Both simulation and measurement data are tested to show the system performance in terms of image resolution.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.183-185
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• 2010

A 2.4 GHz dual-polarized antenna for a Doppler radar is studied. The proposed dual-polarized antenna using a stacked annular ring patch with two co-centric gap-coupled feed lines and a $90^{\circ}$ hybrid exhibits fairly good performance of 22 dB isolation at a center frequency of 2.4 GHz. Using a $90^{\circ}$ hybrid, a right-handed circular polarization for the transmitter and a left-handed circular polarization for the receiver are implemented. The gain of the designed antenna is about 0 dBi over operating frequencies. The antenna size including a ground plane is only $40{\times}40\;mm^2$.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.5
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• pp.507-512
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• 2007

This paper presents a tracking filter with ship's motion compensation for a ship-borne radar tracking system. The ship's maneuver is described by displacement and rotational motions in the ship-centered east-north frame. The first order Taylor series approximation of the measurement error covariance of the converted measurement is derived in the ship-centered east-north frame. The ship's maneuver is compensated by incorporating the measurement error covariance of the converted measurement and displacement of the position state in the tracking filter. The simulation results via 500 Monte-Carlo runs show that the proposed method follows the target successfully and provides consistent tracking performance during ship's maneuvers while the conventional tracking filter without ship motion compensation fails to track during such periods.