• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.382-389
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• 2013

In anti-jamming GPS receiver, adaptive signal processing techniques in which the radiation pattern of adaptive array antenna of elements may be adaptively changed used to reject interference, clutter, and jamming signals. In this paper, I describes adaptive signal processing technique using the sample matrix inversion(SMI) algorithm. This adaptive signal processing technique can be applied effectively to wideband/narrowband anti-jamming GPS receiver because it does not consider the satellite signal directions and GPS signal power level exists below the thermal noise. I also analyzed the effects of covariance matrix sample size and diagonal loading technique on the system performance of five-element circular array antenna. To attain near optimum performance, more samples required for calculation covariance matrix. Diagonal loading technique reduces the system nulling capability against low-power jamming signals, but this technique improves robustness of adaptive array antenna.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.822-825
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• 1999

This paper compares two methods of GPS/INS integration ; tightly-coupled integration ana loosely-coupled integration. In the tightly -coupled method an integrated Kalman filter is designed to process raw GPS measurement data for state update and INS data for propagation. The loosely-coupled integration method uses the solution outputs from a stand-alone GPS receiver for update. The loosely-coupled method is simpler and can readily be applied to off-the-self receivers and sensors while the tightly-coupled integration requires access to raw measurement mechanism of the receiver. Simulation result show that the tightly-coupled integration system exhibits better performance and robustness than loosely-coupled integration method.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.114.4-114
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• 2001

Recently, variety services are more and more developed due to supply of PDA, cellular phone, and etc. Also, a services based on location information are very helpful in traffic, shopping, and emergency. Thus the user position is positively necessary for these services. One of the latest applications in GPS is the E911 call service for wireless phones. In this case, current GPS Navigation accuracy meets the FCC requirements but the hardware size and power consumption of GPS is issued for implementation. And, some case of applications need to snapshot location solution with fast TTFF(Time-To-Fist-Fix) than continuous location solution. The software GPS receiver could be the solution ...

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.121-125
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• 2006

A new GPS receiver correlator for the deeply-coupled GPS/INS integration system is proposed in order to the computation time problem of the Kalman filter. The proposed correlator consists of two early, prompt and late arm pairs. One pair is for detecting data bit transition boundary and another is for the correlator value calculation between input and replica signal. By detecting the data bit transition boundary, the measurement calculation time can be made longer than data bit period. As a result of this, the computational time problem of the integrated Kalman filter can be resolved. The validity of the proposed method is given through computer simulations.

• Journal of Astronomy and Space Sciences
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• v.27 no.4
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• pp.345-352
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• 2010

Korea multi-purpose satellite-5 (KOMPSAT-5) is a low earth orbit (LEO) satellite scheduled to be launched in 2010. To satisfy the precision orbit determination (POD) requirement for a high resolution synthetic aperture radar image of KOMPSAT-5, KOMPSAT-5 has atmosphere occultation POD (AOPOD) system which consists of a space-borne dual frequency global positioning system (GPS) receiver and a laser retro reflector array. A space-borne dual frequency GPS receiver on a LEO satellite provides position data for the POD and radio occultation data for scientific applications. This paper describes an overview of AOPOD system and operation concepts of the radio occultation mission in KOMPSAT-5. We showed AOPOD system satisfies the requirements of KOMPSAT-5 in performance and stability.

• Journal of Advanced Navigation Technology
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• v.1 no.1
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• pp.23-34
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• 1997

A multi-channel digital GPS receiver has been developed including a RF-to-IF engine (engine 1), a digital signal processing engine (engine 2) with a microprocessor interfacing, and a navigation software. A high speed SiGe heterojunction bipolar transistor (HBT) as a active device has been mounted on chip-on-board (COB) type hybrid ICs such as LNA, mixer, and VCO in RF front-end of the engine 1 board. A 6-channel digital correlator together with a real-time clock and a microprocessor interface has been realized using an Altera Flex 10K FPGA as well as ASIC technology. Navigation software controlling the correlator for GPS signal tracking, retrieval and storing a message retrieval, and position calculation has been implemented. The GPS receiver was tested using a single channel STR2770 simulator. Successful navigation message retrieval and position determination was confirmed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.1044-1050
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• 2013

This paper analyzes what is mitigated as spoofing attack using the U-Blox Receiver and GPS RF signal generator developed at ETRI. Generally the spoofing attack made the target receiver to be wrong navigation solution by providing false measurement of code and carrier. So we analyzed the impact of spoofing attack through the signal strength and navigation solution. In oder to test of effect of anti-spoofing signal, we consider the signal with antiphase code to spoofing signal and generated GPS normal signal and spoofing signal and anti-spoofing signal using GPS RF signal generator. This paper analyzed that the GPS receiver was responded to the spoofing attack according to code phase difference between spoofing and anti-spoofing signal. We confirmed that the spoofing signal was disappeared by anti-spoofing signal if code phase is an exact match.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.2
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• pp.167-173
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• 2006

Ionosphere is the largest error source on propagation of GPS signals. Dual frequency (L1,L2) GPS receiver can be effectively able to eliminate the ionosphere error by using linear combination of two frequencies, but the single frequency receiver (L1) have to compute the ionosphere error. In this research, we developed the new ionospheric model with $1^{\circ}$ by $1^{\circ}$ spatial resolution based on the grid from using 9 GPS reference stations which have been operated by KASI (Korea Astronomy and Space Science Institute) and computed TEC (Total Electron Contents) over South Korea by epoch. This paper gives the positioning results of Klobuchar model with that of a newly developed KASI regional ionospheric model and shows the positioning precision of the KASI regional ionospheric model along with TEC variation of ionosphere.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1388-1391
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• 1996

This paper presents the structure and functions of the differential beacon receiver for receiving DGPS error correction data. The differential beacon receiver is designed using commercially available components. Its functions are being implemented and tested in laboratory. Filed test is scheduled for the end of this year.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.13-17
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• 2017

This paper presents an approach to enable a typical GPS receiver to be much less susceptible to intentional disruption such as jamming and change in link environment. In order for the GPS receiver to cope with jamming and to get adaptivity, a $4{\times}4$ beamforming antenna is designed using metamaterials. The design results show the antenna gain much higher than 5 dBi and the movable beam.