• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.615-625
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• 2012

GPS attitude outputs or carrier phase observables can be effectively utilized to compensate the attitude error of the strapdown inertial navigation system. However, when the integer ambiguity is not correctly resolved and/or a cycle slip occurs, an erroneous GPS output can be obtained. If the erroneous GPS output is applied to the attitude determination GPS/INS (ADGPS/INS) integrated navigation system, the performance of the system can be degraded. This paper proposes an ADGPS/INS integration system using the triple difference carrier phase observables. The proposed integration system contains a cycle slip detection algorithm, in which the inertial information is combined. Computer simulations and flight test were performed to verify effectiveness of the proposed navigation system. Results show that the proposed system gives an accurate and reliable navigation solution even when the integer ambiguity is not correctly resolved and the cycle slip occurs.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.12
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• pp.1067-1075
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• 2002

The system error model for the compensation of the low-cost personal navigation system is derived and the error compensation method using GPS is also proposed. The walking navigation system (WNS) that calculates navigation information through walking detection has small error than INS, but the error also increases with time. In order to improve reliability of the system regardless of time, WNS is integrated with GPS. Since WNS is usually used in urban area, the blockage of CPS signal is frequently occurred. Therefore tightly coupled Kalman filter is used for the integration of WNS and GPS. In this paper, the system model for the design of tightly coupled Kかm filter is designed and measurement is linearized in consideration of moving distance error. It is shown by Monte Carlo simulation that the error is bounded even through the number of visible satellite is less than 4.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.285-289
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• 2006

In this paper, a design and implementation of GPS/Galileo software receiver is given. As a GPS receiver, it is able to perform every function of receiver such as acquisition, code and carrier tracking, navigation bit extraction, navigation data decoding, pseudorange calculations, and position calculations. A method to acquire and track the Galileo BOC(1,1) signal is also required because the correlation of BOC(1,1) signal has multiple peaks different from that of GPS signal. Therefore, a method to detect the main-peak in correlation function of BOC signal is required to avoid false acquisition. In this paper, very-early, very late correlation is implemented to track the correct main peak. The performance of implemented GPS/Galileo software receiver with BOC(1,1) signal tracking feature is evaluated with GPS/Galileo IF signal generator.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.738-743
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• 2012

Kalman filter is generally used in INS/GPS integrated navigation filter. However, the INS with low performance inertia sensor can not find accurate azimuth in initial alignment stage because sensor noise level is too large compare to Earth rotation rate, therefore the performance and stability of Kalman filter can not be guaranteed. In this paper, the extended Kalman filter and particle filter combined filter structure which can be overcome large initial azimuth error is proposed.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.1
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• pp.114-122
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• 2009

An adaptive Kalman filter is designed as a post-navigation filter to improve the accuracy of GPS receiver's navigation performance in high dynamic environments. Not only the adaptive Kalman filter reduces the large noise error of navigation data which is obtained by least square method, but also the filter is not degraded as normal Kalman filter in high acceleration movements because the system noise is estimated. Also an initialization structure of the filter is desisted in consideration for irregular output condition of navigation data by least squared method such as reacquisition status in GPS receiver. The filter performance is verified by GPS simulator which has the simulation capability of high velocity and acceleration. Finally, a vehicle test including DGPS is executed to conform the real improvement of that filter performance. This filter can be applied to various data measurement systems to improve accuracy in high dynamic conditions besides GPS receiver.

• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.763-770
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• 2005

Global Navigation Satellite System (GNSS) has become an indispensable tool for providing precise position, velocity and time information for many applications like traditional surveying and navigation etc. However, Global Positioning System (GPS), which was developed and is maintained and operated by the U.S. Department of Defence (DoD), has monopolized the world industry and market, and hence there exists the situation that most of GNSS users absolutely depend upon the GPS. In order to overcome the monopoly, some countries, such as Russia, Japan and European Union (EU), have developed their own GNSSs, so-called GLONASS, JRANS and Galileo systems. Among them, the most prospective system in near future is EU's Galileo system scheduled to launch in 2008. This research has focused on the next generation GNSS system based on GPS and Gralileo system with developing a GNSS simulation software, named as GIMS2005, which generates and analyzes satellite constellation and measurements. Based on the software, a variety of simulation tests have been carried out to recognize limits of GPS-only system and potential benefits of integrated GPS/Galileo positioning. Geometry simulation results have showed that comparing with GPS-only case, the number qf visual satellites, Dilution of Precision (DOP) values, internal reliabilities and external reliabilities.

• Proceedings of the Korea Society of Design Studies Conference
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• 2005.05a
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• pp.130-131
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• 2005

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.319-326
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• 2009

In this paper, the key technologies of Navigation receiver for GNSS sensor station are presented as a development result of a GNSS ground station in ETRI. A wide-band antenna and RF/IF components and SW signal processing unit to cover the GPS and Galileo signals for GNSS receiver are developed and its performance is verified by using GPS live signal and GNSS RF signal simulator from SpirentTM. We also gather GIOVE-A signal by using H/W antenna and RF/IF units in IF-level as sampling frequency and bit number, 112MHz and 8bits, respectively by using the developed wide-band antenna and RF/IF components. Data acquisition is done by using commercial data acquisition device from National Instrument TM. The gathered data is fed into SW receiver to process Galileo E1 to verify Galileo signal processing by Galileo live signal from GIOVE-A.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.3
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• pp.119-129
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• 2016

This paper presents an integrated navigation system for accurate navigation solution-based safety and convenience services in the vehicular augmented reality (AR)-head up display (HUD) system. For lane-level guidance service, especially, an accurate navigation system is essential. To achieve this, an inertial navigation system (INS)/global positioning system (GPS)/vision/digital map (IGVM) integrated navigation system has been developing. In this paper, the concept of the integrated navigation system is introduced and is implemented based on a multi-model switching filter and vehicle status decided by using the GPS data and inertial measurement unit (IMU) measurements. The performance of the implemented navigation system is verified experimentally.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2520-2527
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• 2015

Position information is important to carry out military operations. In general, GPS is used to estimate position. However, GPS is vulnerable to jamming due to the low received signal strength, therefore GPS can be easily jammed. The relative navigation is an auxiliary navigation system defined in JTIDS. When GPS is jammed, the relative navigation requires ground reference units on the ground to operate accurately. If the ground reference unit does not exist, nodes operated by the relative navigation depend on the inertial navigation system to identify their position. However, this positioning scheme based on only INS causes accumulative position error, therefore the nodes cannot identify their position accurately for a long time. In this paper, we propose an alternative to reduce position error generated by depending inertial navigation system. In order to verify that the performance of proposed scheme is better than that of the existing scheme, various simulations are conducted.