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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Positioning, Navigation, and Timing
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Journal DOI :
The Korean GNSS Society
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Volume & Issues
Volume 2, Issue 2 - Oct 2013
Volume 2, Issue 1 - Apr 2013
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A Satellite Navigation Signal Scheme Using Zadoff-Chu Sequence for Reducing the Signal Acquisition Space
Park, Dae-Soon ; Kim, Jeong-Been ; Lee, Je-Won ; Kim, Kap-Jin ; Song, Kiwon ; Ahn, Jae Min ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 1~8
DOI : 10.11003/JKGS.2013.2.1.001
A signal system for improving the code acquisition complexity of Global Navigation Satellite System (GNSS) receiver is proposed and the receiving correlator scheme is presented accordingly. The proposed signal system is a hierarchical code type with a duplexing configuration which consists of the Zadoff-Chu (ZC) code having a good auto-correlation characteristic and the Pseudo Random Noise (PRN) code for distinguishing satellites. The receiving correlator has the scheme that consists of the primary correlator for the ZC code and the secondary correlator which uses the PRN code for the primary correlation results. The simulation results of code acquisition using the receiving correlator of the proposed signal system show that the proposed signal scheme improves the complexity of GNSS receiver and has the code acquisition performance comparable to the existing GNSS signal system using Coarse/Acquisition (C/A) code.
A Study for Improving the Positioning Accuracy of DGPS Based on Multi-Reference Stations by Applying Exponential Modeling on Pseudorange Corrections
Kim, Koon-Tack ; Park, Kwan-Dong ; Lee, Eunsung ; Heo, Moon Beom ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 9~17
DOI : 10.11003/JKGS.2013.2.1.009
In this paper, a pseudorange correction regeneration algorithm was developed to improve the positioning accuracy of DGPS using multi-reference stations, and the optimal minimum number of reference sites was determined by trying out different numbers of reference. This research was conducted using from two to five sites, and positioning errors of less than 1 m were obtained when pseudorange corrections are collected from at least four reference stations and interpolated as the pseudorange correction at the rover. After determining the optimal minimum number of reference stations, the pseudorange correction regeneration algorithm developed was tested by comparison with the performance of other algorithms. Our approach was developed based on an exponential model. If pseudorange corrections are regenerated using an exponential model, the effect of a small difference in the baseline distance can be enlarged. Therefore, weights can be applied sensitively even when the baseline distance differs by a small amount. Also weights on the baseline distance were applied differently by assigning weights depending on the difference of the longest and shortest baselines. Through this method, the positioning accuracy improved by 19% compared to the result of previous studies.
Relative Positioning of Vehicles Carrying Hazardous Materials Using Real-Time Kinematic GPS
Kim, Hee Sung ; Choi, Kwang Ho ; Lee, Je Young ; Lim, Joon Hoo ; Chun, Se Bum ; Lee, Hyung Keun ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 19~31
DOI : 10.11003/JKGS.2013.2.1.019
It is well known that the accident of vehicles carrying hazardous materials incurs huge losses economically and socially. To detect and respond rapidly against the accident of a vehicle carrying hazardous materials, it is essential to estimate the relative navigation information between the forward tractor module and the backward trailer module of the vehicle reliably and accurately. In this paper, a precise relative positioning system based on GPS is designed, implemented, and evaluated as a prerequisite to design an effective relative navigation system for the vehicle carrying hazardous materials. An experiment using field-collected 10 Hz real GPS measurements showed that the designed relative positioning system achieves 22 cm accuracy within 15 epochs by float solutions. Also, it was found that cm-level integer solutions can be generated reliably after the quick convergence of float solutions.
A Development of GPS SIS Anomalies Generation Software
Han, Younghoon ; Ko, Jaeyoung ; Shin, Mi Young ; Cho, Deuk Jae ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 33~40
DOI : 10.11003/JKGS.2013.2.1.033
In this paper, GPS signal anomaly generation software is proposed which can be used for the analysis of GPS signal anomaly effect and the design, verification, and operation test of anomalous signal monitoring technique. For the implementation of anomalous signal generation technique, anomalous signals are generated using a commercial signal generation simulator, and their effects and characteristics are analyzed. An error model equation is proposed from the result of analysis, and the anomalous signal generation software is constructed based on this equation. The proposed anomalous signal generation software has high scalability so that users can easily utilize and apply, and is economical as the additional cost for purchasing equipment is not necessary. Also, it is capable of anomalous signal generation based on real-time signal by comparing with the commercial signal generation simulator.
Preliminary Design of GBAS Onboard Test Equipment
Jeong, Myeong-Sook ; Ko, Wan-Jin ; Bae, Joong Won ; Jun, Hyang Sig ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 41~48
DOI : 10.11003/JKGS.2013.2.1.041
When the ground subsystem of Ground Based Augmentation System(GBAS) is installed at the airport, the functions and performance of subsystem should be evaluated through ground and flight testing at the pre-commissioning phase. In the case of GBAS flight testing, it can be conducted by the existing flight check aircraft, but the GBAS ground testing requires the development of specially customized equipment to perform the ground testing. Therefore, this paper describes the preliminary design of GBAS onboard test equipment which can be independently used for the GBAS ground testing and flight testing on a car and an aircraft.
Performance Analysis of Pseudolite Tropospheric Delay Models Using Radiosonde Meteorological Data
So, Hyoungmin ; Park, Junpyo ; Song, Kiwon ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 49~57
DOI : 10.11003/JKGS.2013.2.1.049
When pseudolite navigation system is applied to wide area, the tropospheric delay is the main error factor. In this study, we experimentally compared and analyzed the performance of the conventional pseudolite tropospheric delay models. The integration method using radiosonde meteorological data was suggested to derive the reference value for the comparison and analysis. Flight tests were carried out to analyze the performance of the tropospheric delay models according to the elevation angle and distance conditions between the user receiver and the pseudolite. As the results of this study, we provided the basis for the choice of tropospheric delay model appropriate to the relative location characteristics of the pseudolite and the user.
Performance Evaluation of Ionosphere Modeling Using Spherical Harmonics in the Korean Peninsula
Han, Deokhwa ; Yun, Ho ; Kee, Changdon ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 59~65
DOI : 10.11003/JKGS.2013.2.1.059
The signal broadcast from a GPS satellite experiences code delay and carrier phase advance while passing through the ionosphere, which causes a signal error. Many ionosphere models have been studied to correct this ionospheric delay error. In this paper, the ionosphere modeling for the Korean Peninsula was carried out using a spherical harmonics based model. In contrast to the previous studies, we considered a real-time ionospheric delay correction model using fewer number of basis functions. The modeling performance was evaluated by comparing with a grid model. Total number of basis functions was set to be identical to the number of grid points in the grid model. The performance test was conducted using the GPS measurements collected from 5 reference stations during 24 hours. In the test result, the modeling residual error was smaller than that of the existing grid model. However, when the number of measurements was small and the measurements were not evenly distributed, the overall trend was found to be problematic. For improving this problem, we implemented the modeling with additional virtual measurements.
Design of 3-Dimension Remote Controller Applying the EMD Algorithm which Attenuates the Effect of Noise
Yeo, Sang-Rae ; Choi, Heon Ho ; Ko, Jae Young ; Park, Chansik ; Lee, Sang Jeong ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 67~74
DOI : 10.11003/JKGS.2013.2.1.067
In this study, a remote controller was designed using localization technique. The designed remote controller system consists of infrared transmit/receive module for time synchronization, ultrasonic transmit/receive module for measuring the TOA value, and micro-controller for processing the measured data value. For the position estimation method of remote controller, the Savarese method was used which does not have a problem of diverging solution depending on initial value. The noise included in the measured value was removed by separating the signal and noise with the use of EMD method which is the non-stationary signal analysis technique. The designed system was tested by constructing a simulation environment, and the improvement of accuracy and precision for the application of EMD method was examined.
A Design of LORAN Disciplined Oscillator
Hwang, Sang-Wook ; Choi, Yun Sub ; Yeo, Sang-Rae ; Park, Chansik ; Yang, Sung-Hoon ; Lee, Sang Jeong ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 75~80
DOI : 10.11003/JKGS.2013.2.1.075
This article presents the design of long range navigation (LORAN)-disciplined oscillator (LDO), employing the timing information of the LORAN system, which was developed as a backup system that corrects the vulnerability of the global positioning system (GPS)-based timing information utilization. The LDO designed on the basis of hardware generates a timing source synchronized with reference to the timing information of the LORAN-C receiver. As for the LDO-based timing information measurement, the Kalman filter was applied to estimate the measurement of which variance was minimized so that the stability performance could be improved. The oven-controlled crystal oscillator (OCXO) was employed as the local oscillator of the LDO. The controller was operated by digital proportional-integral-derivative (PID) controlling method. The LDO performance evaluation environment that takes into account the additional secondary factor (ASF) of the LORAN signals allows for the relative ASF observation and data collection using the coordinated universal time (UTC). The collected observation data are used to analyze the effect of ASF on propagation delay. The LDO stability performance was presented by the results of the LDO frequency measurements from which the ASF was excluded.
1-Point Ransac Based Robust Visual Odometry
Nguyen, Van Cuong ; Heo, Moon Beom ; Jee, Gyu-In ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 81~89
DOI : 10.11003/JKGS.2013.2.1.081
Many of the current visual odometry algorithms suffer from some extreme limitations such as requiring a high amount of computation time, complex algorithms, and not working in urban environments. In this paper, we present an approach that can solve all the above problems using a single camera. Using a planar motion assumption and Ackermann's principle of motion, we construct the vehicle's motion model as a circular planar motion (2DOF). Then, we adopt a 1-point method to improve the Ransac algorithm and the relative motion estimation. In the Ransac algorithm, we use a 1-point method to generate the hypothesis and then adopt the Levenberg-Marquardt method to minimize the geometric error function and verify inliers. In motion estimation, we combine the 1-point method with a simple least-square minimization solution to handle cases in which only a few feature points are present. The 1-point method is the key to speed up our visual odometry application to real-time systems. Finally, a Bundle Adjustment algorithm is adopted to refine the pose estimation. The results on real datasets in urban dynamic environments demonstrate the effectiveness of our proposed algorithm.
Radio Frequency Based Emergency Exit Node Technology
Choi, Youngwoo ; Kim, Dong Kyoo ; Kang, Do Wook ; Choi, Wan Sik ;
Journal of Positioning, Navigation, and Timing, volume 2, issue 1, 2013, Pages 91~100
DOI : 10.11003/JKGS.2013.2.1.091
This paper introduces an indoor sensor fusion wireless communication device which provides the Location Based Service (LBS) using fire prevention facility. The proposed system can provide information in real time by optimizing the hardware of Wi-Fi technology. The proposed system can be applied to a fire prevention facility (i.e., emergency exit) and provide information such as escape way, emergency exit location, and accident alarm to smart phone users, dedicated terminal holders, or other related organizations including guardians, which makes them respond instantly with lifesaving, emergency mobilization, etc. Also, the proposed system can be used as a composite fire detection sensor node with additional fire and motion detect sensors.