• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.5
• /
• pp.777-782
• /
• 2017

The Signal Intelligence (SIGINT) system based on the adaptive beamformer, comprised of the AOA estimator followed by the interference canceller, is a cutting edge technology for collecting various signal information utilizing all sorts of devices such as the radar and satellite. In this paper, we present the efficient adaptive SIGINT structure consisted of an AOA estimator and an adaptive beamformer. For estimating AOA information of various signals, we employ the Multiple Signal Classification (MUSIC) algorithm and for efficiently suppressing high-power interference signals, we employ the Minimum Variance Distortionless Response (MVDR) algorithm. Also, we provide computer simulation examples to verify the performance of the presented adaptive beamformer structure.

• Journal of Internet Computing and Services
• /
• v.24 no.2
• /
• pp.27-36
• /
• 2023

Waveguides are transmission lines that guide electromagnetic waves in the desired direction and are utilized in various fields such as medical devices, radar systems, and satellite communications. Computational electromagnetics (CEM) is essential for designing and optimizing waveguides. The finite element method (FEM), which is one of the numerical analysis techniques, is efficient in solving closed problems such as waveguides. In order to apply FEM for waveguide analysis, boundary conditions that truncate the computational domain are required. This paper performs electromagnetic simulations using absorbing boundary conditions (ABC) and waveguide port boundary conditions (WPBC) in 2/D and 3/D waveguides using the finite element method and compared their performances. The accuracy of the analysis was verified by comparing the results with HFSS, a representative commercial electromagnetic simulation software. Simulation results confirm that applying WPBC allows for smaller analysis domains than ABC.

• Journal of Digital Convergence
• /
• v.11 no.7
• /
• pp.201-207
• /
• 2013

The chirp signaling has been mainly used in radar systems due to its good correlation characteristics, and nowadays it is applied to real time locating system(RTLS). The RTLS with chirp signaling was chosen as a standard such as ISO/IEC 24730-5 and IEEE 802.15.4a. In this paper, the performance of a real time locating system with chirp signaling was evaluated and simulated with relative distance error rates. We considered three cases of S/I = -30[dB], -20[dB], and -10[dB] with Rician factor K=10 and K=20. The performance was enhanced with K factor improvement by 25%, 27% and 50% for respective three cases of S/I. As results, in case of S/I < -20[dB], the minimum signal power is required for performance improvement even though the line of sight component is helpful. And also, in case of S/I ${\geq}$ -20[dB], as the line of sight component is stronger the better performance is obtained.

• Journal of the Institute of Convergence Signal Processing
• /
• v.2 no.1
• /
• pp.12-18
• /
• 2001

SAR radar and FLIR images, which are taken from sensors on aircrafts or satellites, are compressed prior to transmission to facilitate rapid transfer through the limited bandwidth channels. In this case, it is important that it achieves compression ratio as high as possible as well as high target detection rate. In this paper a joint ATR-compression system based on the subband coding and VQ is proposed, which utilizes the encoder as a predictor or classifier for target detection. Simulation result shows that the proposed system achieves a relatively high level of target detection performance as well as a high compression ratio over 200:1.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.2
• /
• pp.49-56
• /
• 2011

One of the most important VANET applications is providing active safety by broadcasting emergency messages. In order to prevent broadcast storm of flooding-based broadcasting scheme in which any node receiving message will rebroadcast, the existing protocols use the different methods to limit the number of relay nodes. Nevertheless, the existing protocols have low delivery ratio with high traffic density and cause message overhead. Currently, the dramatic increase in the number of vehicles equipped with Global Positioning System (GPS) and onboard radar created new application scenarios that were not feasible before. Consequently, we proposed a broadcasting protocol that selects relay node by using GPS-based position information and detecting neighboring vehicles with the help of onboard radar to. Simulation results show that our proposed protocol has better performance than the existing schemes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.11
• /
• pp.1248-1258
• /
• 2010

In this paper, a method for simultaneously realizing the sum and difference patterns which are required in the monopulse radar sensor systems, is presented by using single taper array antenna with rectangular microstrip patches. The widths of patches are first determined by the voltage weights which are synthesized for the fundamental array factor patterns to be applied to the monopulse operation by using the sidelobe levels(SLLs) control technique. As the bi-directionally series-fed technique is applied and the lengths of connecting lines between patches are appropriately adjusted, the single array generates two phase-shifted beams which activates out-of-phase and in-phase ports of a $180^{\circ}$ hybrid coupler to synthesize the sum and difference patterns. The simulated results on the configuration designed at 9.5 GHz are compared with measured results showing the validity of the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.10a
• /
• pp.398-402
• /
• 2003

In this paper, a VCDRO(Voltage Control Dielectric Resonator Oscillator) applied to FMCW(Frequency Modulated Continuous Wave)Radar as stable source is implemented and constructed with a MESFET for low noise, a dielectric resonator of high frequency selectivity, and high Q varator diode to obtain a good phase noise performance and stable sweep characteristics. The designed circuits is simulated thrash harmonic balance simulation technique to provide the optimum performance. The measured result of a fabricated VCDRO shows that output is 2.22dBm at 12.05GHz, harmonic suppression -30dBc, phase noise -130dBc at 100kHz offset, and sweep range of varator diode $\pm$18.7MHz, respectively. This oscillator will be available to FMCW Radar.

• Journal of Navigation and Port Research
• /
• v.27 no.4
• /
• pp.465-469
• /
• 2003

It has well known that MUSIC and ESPRIT algorithms estimate angle of arrival(AOA) with high resolution by eigenvalue decomposition of the covariance matrix which were obtained from the array antennas, However, the disadvantage of MUSIC and ESPRIT is that they are computationally ineffective, and then they are difficult to implement in real time. the other problem of MUSIC and ESPRIT is to require calibrated antennas with uniform features, and are sensitive ti the manufacturing fault and other physical uncertainties. To overcome these disadvantages, several method using neural model have been study. For multiple signals, those methods require huge training data prior to AOA estimation. This paper proposes the algorithm for AOA estimation by interconnected Hopfield neural model. Computer simulations show the validity of the proposed algorithm. It follows that the proposed method yields better AOA estimates than MUSIC. Moreover, out method does not require huge training procedure and only assigns interconnected coefficients to the neural network prior to AOA estimation.

• Journal of Advanced Navigation Technology
• /
• v.24 no.3
• /
• pp.224-231
• /
• 2020

An optical tracking plays an important role for measurement operation, as it is responsible for low altitude measurements that are difficult to obtain with radar systems. Since the existing optical tracking systems have not been developed in the proving ground itself so far, it is difficult to modify them to fit the environment of the proving ground. Also, they are designed as a vehicle-mounted type, so there is a limitation in selecting an optimal site. The in-house developed small optical tracking system is designed with a simple configuration to overcome these shortcomings and makes it possible for operators to operate the system at any place in the proving ground. In addition, there has been a need of developing small optical trackers by ourselves to be prepared for future research so that artificial intelligence (AI) can be applied to the optical tracking systems. In this paper, we described the design concept of the small optical tracker, the configuration of the components to implement the basic tracking function, and showed the results of the simulation to set the configuration of the equipment according to the characteristics of the flight targets.

• Journal of Advanced Navigation Technology
• /
• v.19 no.6
• /
• pp.465-472
• /
• 2015

In order to improve the performance of TCAS it should improve the performance of the sensor, which transmits a variety of information. In this paper, To improve the performance of the existing radar sensors such as being used in behalf of the next generation air traffic control system, ads-b the applied. In addition, ADS-B in a high precision by using information from the correction GPS system, SBAS assume would be able to apply an improved location accuracy for TCAS and analyzed TCAS and ADS-B. Played the simulation results, TCAS equipment receives the help of these ADS-B can calculate a CPA to determine the position of the aircraft in advance, and it was confirmed that it is possible to reduce the unnecessary RA operation, also, the pilot reduction and the workload, it has advantages such as fuel consumption and time associated with the reduced operation unnecessary RA was confirmed.