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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Advanced Navigation Technology
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Journal DOI :
The Korea Navigation Institute
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Volume & Issues
Volume 8, Issue 2 - Dec 2004
Volume 8, Issue 1 - Jun 2004
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A Multiple Quantum Well Electro-absorption Modulator for Broadband Picocell Applications
Song, Ju Bin ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 91~97
This paper presents the development of InGaAsP multiple quantum well asymmetric Fabry-Perot modulators(AFPM), which have a vertical structure and high performance and describes measurements of devices operating at 10GHz for next generation broadband wireless communication applications such as picocell systems. Advantages of the AFPM include low drive voltage, which is less than -2V, and -3dB coupling loss, good flatness of the frequency response and simple fiber alignment. A simple link demonstration has been introduced, resulting in 92dB/Hz spurious free dynamic range and 40dB inter-modulation distortion. This modulator could be use for broadband radio over fiber systems such as picocell and multiple RF links.
Design of a Warning System Using Radio Beacon Signal to Avoid Hazardous Area in VFR Mode
Kim, Yeon-Myung ; Park, Dong-Young ; Yun, Tae-Won ; Hwang, Byong-Won ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 98~104
When a straight-in landing from an instrument approach using ILS or VOR/DME is not possible or desirable because of topographical reason or bad weather, a circling approach maneuver is initiated by the pilot to align the aircraft with a runway for landing. Visual contact with the runway is necessary while conducting a circle to land maneuver. This research is to develop a new warning system based on a convention marker system which alerts pilots to watch out for exceeding the circling approach area. The airborne system also uses the same receiver unit without any new installations. The objective of this research is to design and develop a Yagi antenna in a special form. The research includes computer simulations to determine the size of antenna radiation pattern and to compute an expected flight path in case of alarm to validate effectiveness of the system.
Design of Navigation System for Low Cost Unmanned Aerial Vehicle
Lee, Jang-Ho ; Kim, Sung-Pil ; Park, Mu-Hyeok ; Ahn, Iee-Ki ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 105~111
This paper describes the design of navigation system for an unmanned target drone which is operated by Korean army as for anti-air gun shooting training. Current target drone is operated by pilot control of on-board servo motor via remote control system. Automatic flight control system for the target drone greatly reduces work load of ground pilot and can increase application area of the drone. Most UAVs being operated nowdays use high-priced sensors as AHRS and IMU to measure the attitude, but those are costly. This paper introduces the development of low-cost automatic flight control system with low-cost sensors. The integrated automatic flight control system has been developed by integrating combining power module, switching module, monitoring module and RC receiver as an one module. The performance of navigation for low cost unmanned aerial vehicle, unmanned target drone as our test bed in this paper is verified by both Hardware in the loop simulation(HILS) to test performance of GPS as GPS output frequency high and results of flight test.
An Attitude Determination GPS and INS Integration Scheme: Design and Flight Experiment
Kim, Jeong Won ; Hwang, Dong-Hwan ; Lee, Sang Jeong ; Park, Chansik ; Oh, Sang Heon ; Kim, Se Hwan ; Ahn, Lee-Ki ; Lee, Jang-Ho ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 112~119
This paper proposes an attitude determination GPS/INS integrated system scheme for a UAV and presents experimental flight test results. The proposed system is designed as a part of an autopilot system and comprises a GPS attitude determination receiver, an off-the-shelf inertial measurement unit (IMU), and a navigation computer unit (NCU). UAV requires accurate attitude information for stable automatic flight control. The proposed system can provide accurate attitude information for the flight control computer (FCC) so that stable automatic flight control can be achieved. In order to verify the performance of the proposed scheme, an integrated navigation system has been developed. In order to evaluate the developed navigation system, the flight test has been performed. In the flight test, the developed system was shown to provide the position, the velocity and the attitude satisfactorily enough for stable flight control. The accuracy of the attitude information of the developed system was confirmed by comparing attitude of vertical gyro.
Zhou, Xiao ; Heo, Joo ; Chang, KyungHi ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 120~128
Although conventional OFDM/QAM modulation scheme using guard interval is robust to channel induced ISI (Inter-Symbol Interference) in time-domain, it is very sensitive to ICI (Inter-Carrier Interference) due to doppler effect in frequency domain. OFDM/OQAM-IOTA modulation scheme utilizes IOTA (Isotropic Orthogonal Transform Algorithm) filter that has orthogonality in time and frequency domain so that it is robust to delay spread and doppler effect. OFDM/OQAM-IOTA system can increase bandwidth effeciency since it does not use guard interval. In this paper, we show the structure of OFDM/OQAM-IOTA and perfect channel estimation scheme for OFDM/OQAM-IOTA system. We also compare OFDM/OQAM-IOTA system and OFDM/QAM system in AWGN and 1-path Rayleigh fading channel. Simulation results show that OFDM/OQAM system outperforms OFDM/QAM system.
Practical Applications Study of the Pseudolite
Chang, Jae-Won ; Kwon, TaeHee ; Lee, Sang Jeong ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 129~135
In this paper, the practical applications of the pseudolite are explained with the basic concept of the pseudolite. Many researches have been developed to improve the performance of the GPS. Most of those researches need the extra equipments. But without the extra equipments, the performance of GPS can be improved only with the change in the software in GPS system. In this paper, the pseudolite and the integrated navigation system including GPS as well as pseudolite only with navigation system for the demand of more precise navigation system are introduced. Also, the advantage of the pseudolite is confirmed by some simulations.
An Efficient Channel Estimation Method in Rapid Fading Channel for OFDM Systems
Kang, Yeon-Seok ; Hwang, Tae-Wook ; Kim, Young-Soo ; Suh, Duk-Young ; Kim, Jin-Sang ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 136~144
In this paper, we present an improved channel estimation method for orthogonal frequency division multiplexing systems using pilot-symbol-aided parameter estimation. Conventional linear minimum mean square error(LMMSE) channel estimation method uses only pilot symbols for channel estimation. So, as the fading channel varies rapidly, a performance is decreased. We proposed a channel estimation method, which estimates channel attenuation in the middle of pilots using pilot symbols and then estimates the whole channel attenuation with pilots and estimated channel attenuation. Compared with conventional LMMSE channel estimation method, the proposed method is significantly robust in a rapid fading channel with high Doppler frequency and delay spread.
A Comparative Performance Analysis of STBC-OFDM Systems Under Frequency-Selective Rayleigh Fading Environments
Lee, Sang-Ho ; Jung, Ho-Chul ; Park, Hyung-Rae ; Kim, Jong-Ho ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 144~154
In this paper we apply the space-time block codes (STBCs), the key technologies for the 4th generation mobile communication systems, to the OFDM system and analyze their performances. First, we derive the signal models for representative STBC schemes and demodulation procedures for each scheme. We also select the parameters for OFDM system considering mobile cellular environments and assign adequate modulation schemes to STBC-OFDM schemes according to the transmission rate from 2bps/Hz to 4bps/Hz. We finally compare and analyze the performances of STBC-OFDM schemes for the selected transmission rates through computer simulations, together with performance comparison when the same modulation scheme being adopted.
Analysis and Modelling of Dynamically Variable Topology of Low Earth Orbit Satellite Networks
Vazhenin, N.A. ; Ka, Min-Ho ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 155~162
Recently, significant interest is shown to creation rather inexpensive global systems communications on base of Low-Earth-Orbit Satellite Networks (LEOSN). One of problems of design and creation LEOSN is development of the stream control methods and estimation it's efficiency in such networks. The given problem is complicated, that the topology of the satellite networks varies in time. It essentially hinders the analytical decision of the given problem. An effective way of overcoming of these difficulties is simulation modeling. For realization of research experiments on learning the information streams routing algorithms in LEOSN a special program complex SANET was developed. In the given paper principles of development of LEOSN simulation models and architecture of the manager by the process of a simulation modeling of the unit are considered. Methods of promotion of modeling time and architecture of a simulator complex offered in the article allow to boost essentially efficiency of simulation analysis and to ensure simulation modeling of the satellite networks consisting of several hundreds space vehicles.
Performance Analysis of Frequency Synchronization for HDR-WPAN System
Park, Ji-Woo ; Kang, Hee-Gok ; Kim, Jae-Young ; Oh, Chang-Heon ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 163~168
In this paper, we propose a frequency synchronization algorithm using characteristic of CAZAC sequence for HDR-WPAN and analyze the performance by signal constellation and EVM(error vector magnitude). The proposed frequency offset technique estimated each sample phase error of two sequences among 12 CAZAC sequences which have excellent autocorrelated characteristic. Estimated phase error is multiplied to each sample of next sequence for compensating the frequency offset. The remaining frequency offset after compensating it with two sequences has maximum 0.002 offsest ranges at each sample. The computer simulation proved that the permission of EVM value had satisfied in the case of DQPSK at 20[dB].
A Study on the Digital Watermarking Embedded Transmission of Still Image in Wireless Multimedia Communication Environment
Jo, Song-Back ; Lee, Yang-Sun ; Kang, Heau-Jo ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 169~175
We analyzed about digital watermarking embedded transmission of still image in wireless multimedia communication environment. Also, we proposed improved watermark techniques. It effects that get in original image than method to use conventional image is less and shows robust watermark restoration ability from outside attack. Performance analysis achieved about still image and restoration of watermark information using OFDM/QPSK still image transmission system in wireless channel environment. Analysis result, VI watermark performance that influence in original image is very small. And it could know that show high restoration performance. Also, It showed superior copyright information extraction performance than image watermark in wireless channel environment of same transmission error condition.
Design and Implementation of two-stage Low Noise Amplifier for S-band
Cho, Hyun-Sik ; Kang, Sang-Rok ; Kim, Jang-Gu ; Choi, Byung-Ha ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 176~183
In this paper, two-stage low noise amplifier(LNA) for S-band is designed and implemented using ATF54143 HEMT of HP CO. In order to get noise figure and input VSWR to be wanted, it is considered input VSWR and noise figure simultaneously in matching-circuit designing. The fabricated two-stage low noise amplifier has the gain of 27.8dB, input VSWR and output VSWR under 1.5.
Design & Fabrication of a Feedforward Power Amplifier for 900 MHz Band RFID Readers
Jung, Byoung-Hee ; Chae, Gyu-Sung ; Kim, Chang-Woo ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 184~190
A feedforward linear power amplifier (FLPA) has been developed for UHF-band RFID reader applications. The main and error amplifiers are composed of a 2 stage so that linearity of the FLPA can be improved. The FLPA has been implemented on an FR-4 substrate (Er=4.7 and thickness=0.8 mm) with 3-dB and 10-dB hybrid couplers for input/output power divider and combiner. For 2-tone measurement (input level=-11 dBm at
=915 MHz and
=916 MHz), the FLPA exhibits a -18.52 dBm of
, which indicates that
cancellation with feedforward loop is more than 27 dB. From 890 to 960 MHz, 1-dB gain compression output power and power gain of the FLPA are higher than 30 dBm and 40 dB, respectively.
An Adaptive Viterbi Decoder Architecture Using Reduced State Transition Paths
Ko, Hyoungmin ; Cho, Won-Kyung ; Kim, Jinsang ;
The Journal of Advanced Navigation Technology, volume 8, issue 2, 2004, Pages 190~196
The development of a new hardware structure which can implement the viterbi algorithm efficiently is required for applications such as a software radio because the viterbi algorithm, which is an error correction code function for the second and the third generation of mobile communication, needs a lot of arithmetic operations. The length of K in the viterbi algorithm different from each standard, for examples, K=7 in case of IS-95 standard and GSM standard, and K=9 in case of WCDMA and CDMA2000. In this paper, we propose a new hardware structure of an adaptive viterbi decoder which can decode the constraint length in K=3~9 and the data rate in 1/2 ~ 1/3. Prototyping results targeted to Altera Cyclon EPIC20F400C8, shows that the proposed hardware structure needs maximum 19,276 logic elements and power dissipation of 222.6 mW.