• The Journal of Information Technology
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• v.12 no.4
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• pp.11-17
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• 2009

In this paper, frequency synthesizer for radar system is designed and developed. Optimizing the phase noise and lock time, each module is designed as two-type PLL circuit, and then the performance of PLL frequency synthesizer is compared. The experiment result shows the lock time of 70 usec, the phase noise of less then 100 dBc, the bandwidth above 500MHz.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.3
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• pp.167-174
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• 2008

This paper presents the technology trend of various active safety systems for vehicle. The safety system is applied to various industry fields and is expected to be spread all over the market. So far, good examples of the developed active safety systems are ACC(Adaptive Cruise Control), CMS(Collision Mitigation Systems) and APSS(Active Pedestrian Safety Systems). And, a basic operation principle, system model and detection performance in a UWB radar for vehicle is investigated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.198-207
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• 2016

Bistatric radar can perform detection and identification for stealth targets that are rarely detected by the conventional monostatic radar. However, high resolution range profile(HRRP) generated from the received signal in the bistatic radar cannot show exact range information of the target because the bistatic geometry lead to the distortions of the bistatic HRRP. In addition, electromagnetic scattering mechanisms of the target are varied depending on the bistatic geometry. Thus, efficient database construction is a crucial factor to achieve successful classification capability in bistatic target identification. In this paper, a database construction method based on realistic flight scenarios of a target, which provides a reliable identification performance for the monostatic radar, is applied to bistatic target identification. Then, the capability and efficiency of the method is analyzed. Simulation results show that reliable identification performance can be achieved using the database construction based on the flight scenarios when the target is a considerable distance away from the bistatic radar.

• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.63-68
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• 2017

SAR(Synthetic Aperture Radar) uses electromagnetic signals to acquire ground information and has been used for wide coverage reconnaissance missions regardless of weather conditions. However SAR is known to be vulnerable to interference signals by other communication devices or radar instruments and may suffer from undesirable performance degradations and image quality. In this paper, a modified Eigen-subspace based filter is proposed that can be easily applied to SAR images affected by interference signals. The method of constructing Eigen-subspace based filter is briefly described and various simulations are performed to show the performance of the interference mitigation process. The suppression filter is applied to a ALOS PALSAR raw data affected by interfering signals in order to verify its superiority over the Notch filter.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.80-86
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• 2010

Compressive Sensing (CS) has been widely studied as a promising technique in many applications. The CS theory tells that a signal that is known to be sparse in a specific basis can be reconstructed using convex optimization from far fewer samples than traditional methods use. In this paper, we apply CS technique to Multiple-input multiple-output (MIMO) radar systems which employ uniform linear arrays (ULA). Especially, we investigate the problem of finding the direction-of-arrival (DOA) using CS technique and compare the performance with the conventional adaptive MIMO techniques. The results suggest the CS method can provide the similar performance with far fewer snapshots than the conventional adaptive techniques.

• Journal of the Korean Society of Safety
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• v.23 no.1
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• pp.46-50
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• 2008

The purpose of the present study was to investigate the mariner's information characteristics in ship-ta-ship collision situation using the full mission ship-handling simulator. Risk levels of ship-to-ship collision were manipulated by whether the target ship complies with the naval regulations and by movement patterns of target ship. Dependent variables reflecting mariner's information characteristics in ship-ta-ship collision situation were measured in terms of radar detection reaction time, free recall performance of past navigation situation, and subjective ratings for the task difficulty. The results showed that, in general, the mariners appeared to be deteriorated in their radar detection reaction time and free recall performance as the risk of ship-ta-ship collision increased. Also, the mariners tended to rate required tasks more difficult in the high risk ship-ta-ship collision situation.

• Journal of information and communication convergence engineering
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• v.15 no.3
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• pp.175-181
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• 2017

This paper describes the upgrade of an existing wave information retrieval algorithm by employing noise reduction in the pixel domain. Several algorithms for collecting wave information parameters from X-band radar image sequences including the wind field and current velocity have been developed over the past three decades. Using these algorithms, a band-pass filter (BPF) is applied to remove the non-wave contribution from the image spectra after the sea surface current velocity has been computed. However, such BPF designs have been both complex and insufficient in removing undesired components in X-band radar images. For this study, to improve the performance of wave information retrieval, an efficient noise reduction algorithm is incorporated into a regular wave information retrieval process. That is, the proposed algorithm was designed for operation in a more proper manner by effectively removing the undesired components in the pixel domain. Experiment results demonstrate that the proposed algorithm produces very close estimates to the buoy data records under undesirable noise conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.2
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• pp.109-116
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• 2014

In this paper, we propose a frequency reuse method for efficient frequency use of multi-site weather radar. Our method uses a set of orthogonal pulse compression codes and CLEAN algorithm for sidelobe interference cancellation. Computer simulation results show that performance of proposed method meet performance requirements of [1], The current S-band weather radars in South Korea use the 8 different frequency channels to avoid interference. Using proposed method, number of occupied channels can reduce from 8 to 1, the 7 frequency channels may be use for other services.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.6
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• pp.140-146
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• 1989

In many situations, radar targets are embedded in a clutter environment and clutter rejection is required. The clutter is unwanted radar echoes and may arise owing to reflections from ground and weather disturbances and statistical properties of the clutter vary with range and azimuth as well as time. That is, adaptive signal processing is required. In this paper, a clutter suppression algorithm based on the clutter whitening filter (WF) and doppler filter bank(DFB) is described which provides improved performance compared with conventional nonadaptive clutter suppression algorithm that is the cascaded moving target indicator (MTI) and (DFB). The clutter whitening filter algorithm is based on the Burg's maximum entropy method.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.3
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• pp.224-232
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• 2015

In order to develop an active safety system which avoids or mitigates collisions with preceding vehicles such as autonomous emergency braking (AEB), accurate state estimation of the nearby vehicles is very important. In this paper, an algorithm is proposed using 3 dynamic models to better estimate the state of a vehicle which has various dynamic patterns in both longitudinal and lateral direction. In particular, the proposed algorithm is based on the Interacting Multiple Model (IMM) method which employs three different dynamic models, in cruise mode, lateral maneuver mode and longitudinal maneuver mode. In addition, a Probabilistic Data Association Filter (PDAF) is utilized as a data association algorithm which can improve the reliability of the measurement under a clutter environment. In order to verify the performance of the proposed method, it is simulated in comparison with a Kalman filter method which employs a single dynamic model. Finally, the proposed method is validated using radar data obtained from the field test in the proving ground.