• Title/Summary/Keyword: Carrier wave

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Long Distance Transmission System of Tag's ID in RFID System (전자인식 시스템에서 택 ID의 원거리 전송 시스템)

  • Kim, Dong-Hun;Jo, Hyeong-Guk
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2009.05a
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    • pp.63-67
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    • 2009
  • In RFID system, Tag's Identification data is processed in host computer by application program. Example of application program is parking administration program, library state program etc.. Tag's ID that is recognized in reader is inputted to the Host computer. Application program of computer searches data in DB of computer such as Tag ID. After finding the same ID, host computer send to control command to driver H/W in accordance with application purpose. But, It need to confirm in long distance whether achievement process is acted normally. There will be the 2 methods, when we monitors the process in long distance. One is wired monitoring system, another is wireless monitoring system. Among wire method, internet communication network is useful. RFID system manufacture first in this treatise. RFID system Embody using EM4095 chip that is doing 125KHz by carrier wave. Tag's characteristic ID is sent in remote place through module that use W3100A chip. This system Manufacture, and data send-receive confirmed using simple application program. Reception confirm by result, and pictures show by whole system and each part. And a control program explained of each part.

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Performance analysis of CSMA based MAC protocols for underwater communications (수중 통신에 적합한 CSMA기반 매체접근제어 프로토콜 연구)

  • Song, Min-Je;Jang, Youn-Seon
    • Journal of IKEEE
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    • v.22 no.4
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    • pp.1068-1072
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    • 2018
  • In underwater communications, there are many challenges due to energy limitations, long propagation delay, low data rate, and high power loss, unlike terrestrial RF communications. Especially, the propagation delay of underwater acoustic channel is five orders of magnitude higher than in electro-magnetic terrestrial channels due to the low speed of sound(1,500m/s). Thus, the MAC protocols for terrestrial communications are not suitable for underwater network. In this paper, we studied the considerations for MAC protocol in underwater acoustic channel. Here, we concentrated on CSMA based MAC protocols. From the results, we confirmed that the number of control packets has an important effect on the performance in underwater environment. These results would be useful in designing MAC protocols for underwater acoustic communications.

Technical Trends in GaN RF Electronic Device and Integrated Circuits for 5G Mobile Telecommunication (5G 이동통신을 위한 GaN RF 전자소자 및 집적회로 기술 동향)

  • Lee, J.M.;Min, B.G.;Chang, W.J.;Ji, H.G.;Cho, K.J.;Kang, D.M.
    • Electronics and Telecommunications Trends
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    • v.36 no.3
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    • pp.53-64
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    • 2021
  • As the 5G service market is expected to grow rapidly, the development of high-power, high-efficiency power amplifiers for the 5G communication infrastructure is indispensable. Gallium nitride (GaN) is attracting great interest as a key device in power devices and integrated circuits due to its wide bandgap, high carrier concentration, high electron mobility, and high-power saturation characteristics. In this study, we investigate the technology trends of Ka-band GaN radio frequency (RF) power devices and integrated circuits for operation in the millimeter-wave band of recent 5G mobile communication services. We review the characteristics of GaN RF high electron mobility transistor (HEMT) devices to implement power amplifiers operating at frequencies around 28 GHz and compare the technology of foreign companies with the device characteristics currently developed by the Electronics and Telecommunication Research Institute (ETRI). In addition, the characteristics of Ka-band GaN monolithic microwave integrated circuit (MMIC) power amplifiers manufactured using various GaN HEMT device technologies are reviewed by comparing characteristics such as frequency band, output power, and output power density of integrated circuits. In addition, by comparing the performance of the power amplifier developed by ETRI, the current status and future direction of domestic GaN power devices and integrated circuit technology will be discussed.

Social Contextual Factors Affecting Career Barriers of Multicultural Adolescents: Focusing on differences by Family Income Class (다문화청소년의 진로장벽에 영향을 미치는 사회맥락요인: 가족 소득계층별 차이를 중심으로)

  • Kim, Youngmi
    • The Journal of the Korea Contents Association
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    • v.21 no.12
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    • pp.536-545
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    • 2021
  • The purpose of this study was to identify the differences of career barriers of multicultural adolescents by family income class. The study also examined the differences of social contextual factors affecting career barriers. A total of 1,265 cases from the sixth wave of Multicultural Adolescents Panel Study was used for the analysis. The main findings are as follows: First, multicultural adolescents showed significant differences in carrier barriers by income class. Second, low-income class adolescents were significantly affected by lack of mother involvement and academic adjustment, and middle-income class were affected by family support, academic adjustment, peer relationships, and adults helping at school. Study findings were discussed in terms of implications for practical intervention on career barriers of multicultural adolescents.

Channel Model and Wireless Link Performance Analysis for Short-Range Wireless Communication Applications in the Terahertz Frequency (테라헤르츠 대역 주파수에서 근거리 무선 통신 응용을 위한 채널 모델 및 무선 링크 성능 분석)

  • Chung, Tae-Jin
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.9
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    • pp.868-882
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    • 2009
  • In this paper, channel model and wireless link performance analysis for the short-range wireless communication system applications in the terahertz frequency which is currently interested in many countries will be described. In order to realize high data rates above 10 Gbps, the more wide bandwidths will be required than the currently available bandwidths of millimeter-wave frequencies, therefore, the carrier frequencies will be pushed to THz range to obtain larger bandwidths. From the THz atmospheric propagation characteristics based on ITU-R P.676-7, the available bandwidths were calculated to be 68, 48 and 45 GHz at the center frequencies of 220, 300 and 350 GHz, respectively. With these larger bandwidths, it was shown from the simulation that higher data rate above 10 Gbps can be achieved using lower order modulation schemes which have spectral efficiency of below 1. The indoor propagation delay spread characteristics were analyzed using a simplified PDP model with respect to building materials. The RMS delay spread was calculated to be 9.23 ns in a room size of $6\;m(L){\times}5\;m(W){\times}2.5\;m(H)$ for the concrete plaster with TE polarization, which is a similar result of below 10 ns from the Ray-Tracing simulation in the reference paper. The indoor wireless link performance analysis results showed that receiver sensitivity was $-56{\sim}-46\;dBm$ over bandwidth of $5{\sim}50\;GHz$ and antenna gain was calculated to be $26.6{\sim}31.6\;dBi$ at link distance of 10m under the BPSK modulation scheme. The maximum achievable data rates were estimated to be 30, 16 and 12 Gbps at the carrier frequencies of 220, 300 and 350 GHz, respectively, under the A WGN and LOS conditions, where it was assumed that the output power of the transmitter is -15 dBm and link distance of 1 m with BER of $10^{-12}$. If the output power of transmitter is increased, the more higher data rate can be achieved than the above results.

Vibration Analysis of Combined Deck Structure-Car System of Car Carriers (자동차운반선(自動車運搬船)의 갑판-차량(甲板-車輛) 연성계(聯成系)의 진동해석(振動解析))

  • S.Y.,Han;K.C.,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.27 no.2
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    • pp.63-77
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    • 1990
  • The combined deckstructure-car system of a car carrier is especially sensitive to hull girder vibrations due to mechanical excitations and wave loads. For the free and forced vibration analysis of the system, the analytical methods based on the receptance method and two schemes for efficient applications of the methods are presented. The methods are especially relevant to dynamical reanalysis of the system subject to design modification or to dynamic optimization. The deck-car system is modelled as a combined system consisting of a stiffened plate representing deck, primary structure, and attached subsystems such as pillars, additional stiffeners and damped spring-mass systems representing cars/trucks. For response calculations of the system subjected to displacement excitations along the boundaries, the support displacement transfer ratio conceptually similar to the receptance is introduced. For the verification of accuracy and calculation efficiency of the proposed methods, numerical and experimental investigations are carried out.

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A Study on Calculation of Protection Ratio for Frequency Coordination in Microwave Relay System Networks (M/W 중계 시스템 망의 주파수 조정을 위한 보호비 계산에 대한 연구)

  • Suh Kyoung-Whoan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.2 s.105
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    • pp.139-147
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    • 2006
  • This paper suggests an efficient method of protection ratio calculation and shows some results applicable to frequency coordination in microwave(M/W) relay system networks, and the net filter discrimination(NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively. NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. In addition, NFD and protection ratio for different systems with channel bandwidth 20 and 40 MHz have been investigated to be used for actual M/W networks. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

Development of Android-Based Photogrammetric Unmanned Aerial Vehicle System (안드로이드 기반 무인항공 사진측량 시스템 개발)

  • Park, Jinwoo;Shin, Dongyoon;Choi, Chuluong;Jeong, Hohyun
    • Korean Journal of Remote Sensing
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    • v.31 no.3
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    • pp.215-226
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    • 2015
  • Normally, aero photography using UAV uses about 430 MHz bandwidth radio frequency (RF) modem and navigates and remotely controls through the connection between UAV and ground control system. When using the exhausting method, it has communication range of 1-2 km with frequent cross line and since wireless communication sends information using radio wave as a carrier, it has 10 mW of signal strength limitation which gave restraints on life my distance communication. The purpose of research is to use communication technologies such as long-term evolution (LTE) of smart camera, Bluetooth, Wi-Fi and other communication modules and cameras that can transfer data to design and develop automatic shooting system that acquires images to UAV at the necessary locations. We conclude that the android based UAV filming and communication module system can not only film images with just one smart camera but also connects UAV system and ground control system together and also able to obtain real-time 3D location information and 3D position information using UAV system, GPS, a gyroscope, an accelerometer, and magnetic measuring sensor which will allow us to use real-time position of the UAV and correction work through aerial triangulation.

A Study on the Ultra Small Size 25 Watt High Power Amplifier for Satellite Mobile Communications System at L-Band (L-band 위성통신 시스템을 위한 극소형 25 Watt 고출력증폭기에 관한 연구)

  • Jeon, Joong-Sung;Ye, Byeong-Duck;Kim, Dong-Il
    • Journal of Navigation and Port Research
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    • v.26 no.1
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    • pp.22-27
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    • 2002
  • The 25 Watt hybrid MIC SSPA has been developed in the frequency rang from 1.6265 GHz to 1.6465 GHz for uplink of INMARST's earth station. To simplify the fabrication process, the whole system is designed of two parts composed of a friving amplifier and a power amplifier. The Motorolas MRF-6401 is used for driving part, the Motorolas MRF-16006 and MRF-16030 is used the power amplifier. We reduced weight and volume of high power amplifier through arranging the bias circuits in the same housing. The realized SSPA has more than 30 dB for gain within 20 MHz bandwidth, and the voltage standing wave ratios(VSWR) of input and output port are less than 1.7, respectively. The output power of 44 dBm is achieved at the 1 dB gain compression point of 106365 GHz These results reveal a high power amplifier of 25 Watt which is the design target. The Proposed SSPA manufacture techniques in this paper can be applied to the implementation of high power amplifiers for some radars and SCPC.

Performance Analysis or MC / DS CDMA System with Hybrid SC / MRC Diversity over Multi-path Fading Channels (다중경로 페이딩 채널에서 Hybrid SC/MRC 기법이 적용된 MC / DS CDMA 시스템의 성능분석)

  • 김원섭;박진수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.7A
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    • pp.748-755
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    • 2004
  • In this paper, the hybrid SC/MRC technique was applied to the MC/DS-CDMA system in the Nakagami-m multi-path fading environment. The applied scheme was compared with other cases when the MRC technique was applied and then performances were analyzed. The result of analysis showed that the performance of the applied system, whose number of branches (L) for the input diversity of each carrier wave was 3 and かme selected number of branches ( Lc) was 2, was better than that of the MRC technique when the Lc of the MRC technique was 2. The performance of the applied system was lower than that of the MRC technique, then the Lc of the MRC technique was 3. However, as the fading index was lowered, which means the telecommunication environment deteriorated, the performance of the hybrid SC/MRC-(2/3) diversity technique when Lc of MRC technique was 3, was almost the same as that of the MRC technique. The hybrid SC/MRC-(2/3) diversity technique shows a similar performance to that of the MRC technique, when the Lc of the MRC technique was 4. Therefore, it was confirmed that the MC/DS-CDMA system could reduce complexity and achieve similar performance to that of the MRC by applying the hybrid SC/MRC technique, which utilized the advantages of the SC technique and high performance of the MRC scheme, rather than the MRC diversity technique that requires bit synchronization, frequency of fading, and phase synchronization for every diversity branch.