• Journal of Wetlands Research
• /
• v.10 no.2
• /
• pp.173-178
• /
• 2008

The habitat composition in the Han-river estuary, where white-naped crane(Grus vipio; endangered migrating bird) spend winter, was analysed by the geographic information system(GIS). And the habitat use pattern of white-naped crane collected by satellite tracking method was analysed. The % composition of seven habitat categories of land cover classification was compared for the buffers of radii 100 m, 200 m, 500 m, and 1 km, respectively, around the white-naped crane position point(n=228), and the statistical analysis was done using chi-square test. The results showed no selective use of habitat area by white-naped crane in the buffers of 100 m, 200 m and 500 m, but showed clear selection of habitat use (p < 0.05) in the case of 1 km buffer.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.19 no.5
• /
• pp.582-589
• /
• 2016

Multi-mode monopulse system is widely used for satellite terminal like UAV because of high tracking accuracy and low size/weight profile. In order to calculate tracking error, Multi-mode monopulse system utilizes high-order mode signal, and it should have enough C/N(carrier to noise) level therefore tracking system needs narrow band filtering of received satellite beacon signal as much as possible. However, UAV suffers for beacon frequency drift derived from Doppler effect due to satellite figure 8 movement and UAV maneuvering. Therefore wideband signal processing needs to be considered in advance for exact doppler compensation and consequent time delay. In this paper, we propose the multi-stage Digital Signal processing system for beacon signal, which could minimize the signal delay under high Doppler and low C/N condition.

• Journal of Advanced Navigation Technology
• /
• v.17 no.6
• /
• pp.810-815
• /
• 2013

In case Wi-Fi network based First responder's position tracking system is used, range measurement must be generated from RSSI finger print database. However, it is impossible to build up finger print database and to perform rescue operation at same time in the scene of rescue. In this paper, improvised Wi-Fi network without finger print database and pedestrian dead reckoning based first responders tracking system is proposed.

• Journal of Astronomy and Space Sciences
• /
• v.5 no.1
• /
• pp.31-43
• /
• 1988

The differential correction process determining osculating orbital elements as correct as possible at a given instant of time from tracking data of artificial satellite was accomplished. Preliminary orbital elements were used as an initial value of the differential correction procedure and iterated until the residual of real observation (O) and computed observation(C) was minimized. Tracking satellite was NOAA-9 or TIROS-N series. Two types of tracking data were prediction data precomputed from mean orbital elements of TBUS and real data obtained from tracking 1.70 GHz HRPT signal of NOAA-9 using 5 meter auto-track antenna in Radio Research Laboratory. Accrding to thacking data either Gause method or Herrick-Gibbs method was applied to preliminary orbit determination. In the differential correction stage we used both of the Escobal(1975)'s analytical method and numerical method using f, g series for the comparision. The results between analytical and numerical ones are nearly consistent. And the differentially corrected orbit converged to the same value in spite of the differences between preliminary orbits of each time span.

• Journal of Astronomy and Space Sciences
• /
• v.12 no.1
• /
• pp.123-132
• /
• 1995

We developed a S/W system to simulate the orbit tracking data as nearly equal as the real data obtained at the tracking antenna by modeling various causes that could have effects on the tracking data (range, range rate, azimuth, elevation) of an artificial satellite. Using the S/W developed we produced delay values of tracking data due to the light-time effect and the terrestrial atmosphere. According to the simulation results due to the Earth atmosphere, the values delayed by the troposhpere were increased as the temperature, relative humidity, and pressure of the troposphere are more larger. However, delay values due to the ionosphere were dependent on both the maximum electron density and the frequencies used. They are more and more increased as the maximum electron density and frequency are more larger. And the delaying values by the light-time effect are more larger by the fast orbital motion as the altitude of an artificial satellite is more lower.

• Journal of Advanced Navigation Technology
• /
• v.15 no.4
• /
• pp.495-501
• /
• 2011

The characteristics of a discriminator estimating a tracking error in a signal tracking loop of a GPS receiver can be affected by the noise power, and the slope of the discriminator function is actually lowered as the noise power increases. In this paper, an algorithm to compensate the lowered slope of the function using the estimated C/N0 is studied, and a new design method of a code tracking which provides more accurate tracking error than a conventional one by adopting the compensation algorithm is proposed. Through the experimental results, finally, it has been check that the accuracy of the proposed DLL is enhanced about 50% when the dynamics of the vehicle is 20g/s.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.39 no.1
• /
• pp.65-70
• /
• 2002

In this thesis, we realized tracking system for the purpose of receiving performance improvement of KOREASAT's signal in Korea peninsula. Using Scan-mode antenna point out receivable area without position information sensor and using step-track algorithm reach to peak level. Furthermore, the performance of the completed system was verified by physical experiments that directly receives satellite signal. And decided the optimal size of steps for tracking speed and structure of the system by reiterative approach experiments.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.9
• /
• pp.875-882
• /
• 2007

In order for a vehicle to follow a predetermined trajectory accurately, its position must be estimated accurately and reliably. In this thesis, we propose trajectory tracking control methods for unmanned vehicle and a positioning system using ultrasonic wave. The positioning problem is an important part of control problem for unmanned navigation of a vehicle. Dead Reckoning is widely used for positioning of vehicle. However this method has problems because it accumulates estimation errors. We propose a new method to increase the accuracy of position estimation using the Ultrasonic Satellite System (USAT). It is shown that we will be able to estimate the position of vehicle precisely, in which errors are not accumulated. And proposed trajectory tracking control methods include both a new path planning method and a lateral control method for vehicle. The experimental results show that the proposed methods enables exact vehicle trajectory tracking even under various environmental factors.

• International Journal of Aeronautical and Space Sciences
• /
• v.11 no.4
• /
• pp.351-359
• /
• 2010

This paper proposes a linear system control algorithm with collision avoidance in multiple satellites. Consideration of collision avoidance is augmented by adding a weighting term in the cost function of the original tracking problem in linear quadratic control (LQC). Because the proposed algorithm relies on a similar solution procedure to the original LQC, its inherent advantages, including gain-robustness and optimality, are preserved. To confirm and visualize the derived algorithm, a simple example of two-vehicle motion in the two-dimensional plane is illustrated. In addition, the proposed collision avoidance control is applied to satellite formation flying, and verified by numerical simulations.

• Journal of IKEEE
• /
• v.26 no.2
• /
• pp.211-218
• /
• 2022

This paper presents a S-band phased array antenna system for receiving LEO satellite telemetry signals. The proposed antenna, which is performed to be beam-tiled along the elevation direction, consists of 16 sub-array assemblies, 16 active circuit modules, a perpendicular feed network and a control/power unit. In order to precisely track an LEO satellite, the developed antenna is placed with its elevation axis along the projected trajectory of the satellite on the earth. The center of antenna aperture is facing to the maximum elevation angle in the LEO trajectory. The beam-tilted angles for tracking LEO satellite are obtained by calculating accurately satellite points. Satellite tracking measurements are carried out in the range of ±30° with the respect to the maximum elevation angle. The S/N ratio of 16.5 dB and the Eb/No of 13.3 dB at the maximum elevation angle are obtained from the measurements. The measured result agrees well with the pre-analyzed system margin.