• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.4
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• pp.73-85
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• 2010

In dense electronic warfare signal environments, the conventional radar identification methods based on the basic parameters such as frequency, pulse width, and pulse repetition interval are confronted by the problem of identification ambiguity. To overcome this critical problem, a new approach introducing scan pattern of radars has been presented. Researches on new identification methods, however, suffer from a practical problem that it is not easy to secure the many radar signals including various scan pattern information and operation parameters. This paper presents a modeling method of radar signals with which we can generate radar signals including various scan pattern types according to the parameters determining the variation pattern of received signal strength. In addition, with the radar signals generated by the proposed model we analyze their characteristics according to the location of an electronic warfare support (ES) system.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.487-495
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• 2022

This paper describes the design and development of a high-power transmit receive module(TRM) for mounting on X-band synthetic aperture radar(SAR) of the NEXTSat-2. The TRM generates a high-power pulse signal with a bandwidth of 100 MHz in the target frequency range of X-band and amplifies a low-noise on the received signal. Tx. path of the TRM has output signal level of more than 200 watts (53.01 dB), pulse droop of 0.35 dB, signal strength change of 0.04 dB during transmission signal output, and phase change of 1.7 ˚. Rx. path has noise figure of 3.99 dB and gain of 37.38 ~ 37.46 dB. It was confirmed the TRM satisfies all requirements. The TRM mounted on the NEXTSat-2 flight model(FM) which will be launched using the KSLV-II (Nuri).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2233-2240
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• 2007

This paper presents the measured path loss exponents and standard deviations using measured data at 60GHz to analyze the propagation characteristics of millimeter wave bands having great demand for picocellular communications. In addition the angle of arrival(AOA) were measured to analyze the arrival direction of muitipath waves affecting the received signal strength. As results of analysis, the pathloss exponents in each environment are found to be lower than 2 for free space pathloss exponent. They were determined with the qualities of bottom materials affecting signal strength. The angles of arrival by multipath waves were different with the circumference structures between transmitter and receiver. That is, the multipath waves excluding direct and ground reflected wave were difficult to find in wide space such a gymnasium and playground, however the wall multipath waves were found to arrive at receiver in the corridor. The multipath waves at 60GHz can be known to hardly affect to the received signal strength because of weak signals compared with direct wave.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.341-343
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• 2014

실내 무선 측위 시스템(IPS : Indoor Positioning System) 중 Wifi 신호를 활용하는 방식의 대부분은 측위를 수행하기 이전에 AP의 mac 정보와 수신세기를 수집 하여 radio map을 구축하고 이후 측위 과정에서 수집되는 AP의 정보와 비교하여 위치를 판단한다. 이 방식은 신호 세기의 변화가 없을 경우 실내에서 매우 높은 정확도로 측위를 수행할 수 있다. 그러나 현실세계에서는 구축된 radio map의 신호에 심각한 영향을 줄 수 있는 여러 가지 상황이 존재한다. 대표적으로 채널 간섭 현상을 둘 수 있다. radio map으로 구축되어 있는 AP의 신호 영역 내에 동일 채널 및 인접 채널을 가지는 AP 및 테더링 기기 등이 신규로 설치될 경우 기존 radio map 신호에 영향을 주어 측위 과정에서 정확도가 떨어지는 문제점이 발생하다. 본 논문에서는 앞서 언급한 문제점을 해결하기 위해 AP의 특성 정보를 다중 그리드 Radio map으로 구성하는 방안을 연구하였다. 이 다중 그리드 Radio map을 통해 측위 단계에서 수집된 AP 신호를 더욱 정확하게 분석하고 신호 변동에 능동적으로 대처할 수 있도록 구성하여 기존의 문제점을 해결할 수 있는 방안에 대하여 제안한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.889-896
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• 2022

Data required in a wireless sensor network environment requires more accurate figures as technology advances and its complexity increases. However, in the case of operating a large number of sensor nodes in a large area, the balance between the power consumed and the data quality that can be acquired accordingly should be considered for that purpose. In particular, in complex, densely populated urban areas or military operations with specific goals, location data requires increasingly detailed and high accuracy over a wide range. In this paper, we propose a method of mounting a Global Positioning System(: GPS) only on some of the sensor nodes deployed in the wireless sensor network and improving the error of GPS location data measured on that sensor node through Angle of Arrival(: AoA) and Received Signal Strength Indicator(: RSSI).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.6
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• pp.1149-1157
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• 1994

In this case of the mobile communication of vehicles with satellite, the signal at attenuation is due to roadside trees. To analyze this signal attenuation, a roadside tree was modeled as different obstacles of rectangular type and then using Fresnel and Kirchhoff diffraction theory, a formula was derived for signal intensity variation caused by the roadside tree model. The signal attenuation of a roadside tree model was obtained by numerical analysis with variation of the elevation angle, the position and distance between a receiver and a transmitter, and these were compared with experimental results. The results of comparison between theoretical and experimental values show, as expected, the good agreement of the signal attenuation trend.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.5
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• pp.105-113
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• 2009

In this paper, a vehicle antenna for AM, FM, TDMB, GPS systems was designed and implemented. AM antenna loaded into small space of shark shape was designed by ferrite turn style antenna. For the FM and TDMB antenna, folded monopole antenna which helical is folded was applied. GPS antenna for achieving characteristics both bandwidth and gain improvement was designed microstrip patch that has air substrate and fractal structure. Receiving signal strengths by the measurement were presented for the AM, FM and TDMB antenna. AM signal strength was -65.7dBm, this strength is almost as same conventional pole antenna as -63.4dBm. It can be replaced conventional pole or glass antenna by the studied antenna. Signal strengths for FM and TDMB were -55.66 and -43.50dBm at center frequency, they are 5~10dB higher than conventional antenna. Measurements of bandwidth and gain for the GPS antenna showed 135 MHz under VSWR 2 : 1 and 4.31dBi, gains over GPS band were 3~5dB higher than ceramic patch antenna.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.90-94
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• 2014

This paper suggests the system that allows nearby firefighters to read about the transmission direction of a distress signal and track the location by RSSI of received distress signal which is transmitted wirelessly after sensing the distress signal of a firefighter using the Wireless Sensor Network(WSN) based on IEEE 802.15.4 and Received Signal Strength Indicator(RSSI) in the building. Also, It was confirmed that the location tracking using RSSI is possible because the difference between theoretical value and experimental value is little when experiment using the proposed system.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.128-133
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• 2020

In this study, an 1-dimensional positioning method using iterative linear regression for path loss expression is proposed. In the proposed method, received signal strengths (RSS) measured in several locations and distances between the measuring locat ions obtained by dead reckoning are used to derive a linear regression for the path loss from the transmitting beacon. In the proposed method, for the distance between the transmitting beacon and a target measuring location, several tentative values are assumed. For each tentative value, a linear regression is obtained. Among the linear regression expressions, the one closest to the known reference RSS value is selected and used to derive the distance to the target location. Test results show that the proposed method is more accurate than path loss model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.8
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• pp.643-650
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• 2014

Recently, the wireless communication applications are studied in various environment by the development of short range communication system like wireless sensor networks. This paper presents the analysis of localization schemes for ship application using received signal strength. The localization schemes using received signal strength from wireless networks are classified under two methods, which are Range based method and Range free method. Range based methods estimate the location with least square estimation based on estimated distance using path-loss model. Range free methods estimated the location with the information of anchor nodes linked to target. Simulation results show the appropriate localization scheme for each cabin environments based on the empirical path-loss model in warship's internal space.