• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.6
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• pp.750-759
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• 2009

FLIR(Forward Looking Infrared) geo-pointing is a function that helps pilots to see a target within the field of view under all coordinates and attitudes of helicopter. Geo-pointing controls FLIR LOS(line of sight) toward known target coordinates by using azimuth and elevation angles calculated from several information such as helicopter coordinates and attitudes, a FLIR position from a GPS antenna, and target coordinates. Geo-pointing performance has been tested and evaluated on the ground to save flight test costs and ensure flight safety. In this paper, design and implementation of a geo-pointing system is described with the results of performance test conducted on the ground test system.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.302-305
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• 2002

본 논문에서는 기존의 원형 링 마이크로스트립 슬롯 안테나에 십자슬롯과 truncated를 통하여 원형편파를 구현할 수 있는 새로운 안테나 구조를 제안하였다. 금전구조는 입력단 설계가 간단하고 정함이 쉬운 전자파 결합방식을 사용하였고, Ansoft HFSS V8.0으로 최적화 한 후 제작 및 측정하였다. 제안된 안테나는 GPS(1.55MHz)대역에서 원형편파(RHCP, LHCP)특성을 만족하고, 각각의 안테나 구조에서 7.74%의 임피던스 대역폭(VSWR$\leq$2)을 갖고 안테나의 방사소자를 소형화하였다. 이는 기존의 월평 링 마이크로스트립 슬롯 안테나의 임피던스 대역폭 및 편파특성을 획기적으로 개선한 것이다.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.207-208
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• 2010

In this paper, we carried out calibration of laser scanning MMS(Mobile Mapping System) using Lynx Mobile Mapper, a new MMS developed at Optech Incorporated. Laser scanning MMS could be defined as an integration of several subsystems. Subsystems are composed of laser scanner, gps receiver and antenna, INS(Inertial Navigation System), DMI(Distance Measurement Instrument). These are obtained 3D spatial information by direct-georeferencing technology. To obtain 3D spatial information, calibration of laser scanning MMS is required prior to operation system, it is similar to airborme lidar system. 145 checkpoints were used to accuracy estimation. The accuracy results are about 5cm(RMSE) for calibration in all directions(east, north, ellipsoidal height).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.310-311
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• 2011

In this paper, refer to necessity about independent navigation system for back up of GPS by LORAN-C and suggest a solution of Co-location modeling of LORAN-C with DGPS and analysing for the interference.

• Korean Journal of Agricultural Science
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• v.42 no.1
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• pp.63-71
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• 2015

Path planning is an essential part for traveling and mowing of autonomous lawn mower tractors. Objectives of the paper were to analyze operation patterns by a skilled farmer, to extract and optimize waypoints, and to demonstrate generation of formatted planned path for autonomous lawn mower tractors. A 27-HP mower tractor was operated by a skilled farmer on grass fields. To measure tractor travel and operation characteristics, an RTK-GPS antenna with a 6-cm RMS error, an inertia motion sensing unit, a gyro compass, a wheel angle sensor, and a mower on/off sensor were mounted on the mower tractor, and all the data were collected at a 10-Hz rate. All the sensor data were transferred through a software program to show the status immediately on the notebook. Planned path was generated using the program parameter settings, mileage and time calculations, and the travel path was plotted using developed software. Based on the human operation patterns, path planning algorithm was suggested for autonomous mower tractor. Finally path generation was demonstrated in a formatted file and graphic display. After optimizing the path planning, a decrease in distance about 13% and saving of the working time about 30% was achieved. Field test data showed some overlap, especially in the turning areas. Results of the study would be useful to implement an autonomous mower tractor, but further research needs to improve the performance.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.97-104
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• 2018

In the conventional direction finding, the antenna is installed at a high position on the ground to detect the position of the target with the environment of the LOS(Line of Sight) as much as the signal receiving environment. However, in order to configure such environment, high cost and installation time were required. In this paper, we use TDOA(Time Difference of Arrival) technique to utilize drones in direction finding, so that four drones can be used for directions finding simulation. Simulations based on drone and TDOA direction finding were constructed using additional signal processing Taylor series and Exact Interactive Algorithm. In the simulation, the receiving power is defined by using the 800MHz path-loss model using the GPS information of the ground direction detection, and the position estimation performance is analyzed when the TDOA technique, the Taylor series, and the Exact Interactive Alogrithm are applied.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.11-20
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• 2016

In this paper, a system that can collect GPS L1 C/A, GLONASS G1, and BDS B1I signals with single front-end receiver was implemented using a universal software radio peripheral (USRP) and its performance was verified. To acquire the global navigation satellite system signals, hardware was configured using USRP, antenna, external low-noise amplifier, and external oscillator. In addition, a value of optimum local oscillator frequency was selected to sample signals from three systems with L1-band with a low sampling rate as much as possible. The comparison result of C/N0 between the signal collection system using the proposed method and commercial receiver using double front-end showed that the proposed system had 0.7 ~ 0.8dB higher than that of commercial receiver for GPS L1 C/A signals and 1 ~ 2 dB lower than that of commercial receiver for GLONASS G1 and BDS B1I. Through the above results, it was verified that signals collected using the three systems with a single USRP had no significant error with that of commercial receiver. In the future, it is expected that the proposed system will be combined with software-defined radio (SDR) and advanced to a receiver that has a re-configuration channel.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.27-32
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• 2019

This study describes the design and implementation of a simulated signal generator to demonstrate the performance of VHF band radar for the detection of small targets in RCS(Radar Cross Section). The transmission and reception antenna beam widths used in the simulated signal generating apparatus may be large, which may cause problems in the degree of isolation. Interference signal immunity and isolation characteristics are improved by considering operating conditions of VHF radar to solve isolation of antennas. Simulated signal generator performs the following: VHF radar transmission and reception correction, simulation signal generation, target Doppler, RCS and distance simulation, remote control, and GPS clock synchronization function. After the fabrication of the simulated signal generator, the main characteristics, such as the output characteristics and the reflection signal simulations, were tested. When the microwave radar assembly is completed in the future, it will be utilized for the performance evaluation of VHF radar.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.621-622
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• 2017

In this paper, a low-complexity FFT processor is proposed for narrow-band interference signal cancellation based array antenna. The proposed FFT pocessor can support the variable length of 64, 128 and 512. By reducing number of non-tirval multipliers with mixed radix-4/2/4/2/4/2 algorithm and flexible multi-path delay commutator(MDC) architecture, the complexity of the proposed FFT processor is dramatically decreased. The proposed FFT processor was designed in Xilinx system generator and Implemented with Xilinx Virtex-7 FPGA. With the proposed architecture, the number of slices for the processor is 11454, and the number of DSP48s is 194.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.3
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• pp.183-188
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• 2018

The Global Navigation Satellite System (GNSS) signal gets delayed as it goes through the troposphere before reaching the GNSS antenna. Various tropospheric models are being used to correct the tropospheric delay. In this study, we compared effectiveness of two popular troposphere correction models: Global Pressure and Temperature (GPT) and Satellite-Based Augmentation System (SBAS). One-year data from a particular site was chosen as the test case. Tropospheric delays were computed using the GPT and SBAS models and compared with the International GNSS Service tropospheric product. The bias of SBAS model computations was 3.4 cm, which is four times lower than that of the GPT model. The cause of higher biases observed in the GPT model is the fact that one cannot get wet delays from the model. If SBAS-based wet delays are added to the hydrostatic delays computed using the GPT model, then the accuracy is similar to that of the full SBAS model. From this study, one can conclude that it is better to use the SBAS model than to use the GPT model in the standard code-pseudorange data processing.