• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1338-1341
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• 1997

In this paper, we propose angular rate computation algorithm using GPS carrier phase. A direct angylar rate masurement has not previously been available form GRS, although its availability is highly desirable for use in state feedback control. So we propose angular rate computationalgorithm which derive angular rate from the velocity of differentiated carrier phase og GPS. The proposed algorithm contains attitude determination using double-differentiated carrier phase and 2 baseline configuration whcih provide more practical applications than 3 baseline.

• 한국항공우주학회지
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• 제34권11호
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• pp.42-46
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• 2006

SDINS 운항중 정렬에 적용 가능한 GPS 반송파 위상변화율 측정 모델을 유도하여 새로운 SDINS/GPS 복합항법 시스템 구성 방법을 제안한다. 제안된 SDINS/GPS 복합항법 필터의 성능 분석을 공분산 해석기법을 이용하여 수행하고 이의 결과를 실제 차량 실험을 통하여 검증한다. 제안된 결합기법은 2개 이상의 안테나를 갖는 SDINS/GPS 결합시스템에 적용가능하며 기수각 추정에 직접적으로 연계된 GPS 측정치를 생성함으로써 빠른 SDINS의 기수각 추정을 가능하게 함으로써 SDINS/GPS의 항법 성능을 향상시키게 된다.

• 정보통신설비학회논문지
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• 제4권1호
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• pp.1-6
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• 2005

As an application of the GPS/SDINS integration for its synergistic results, the alignments of the SDINS utilizing GPS carrier phase rate measurements is introduced. A measurement model of GPS carrier phase rate, which does not require integer ambiguity determination process, is newly derived in order to be adopted with the SDINS in-flight alignment process. For in-flight alignment, the performance of the GPS/SDINS integration method suggested in this paper is analyzed using the covariance analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.189-191
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• 2006

This paper analyzes effect of the spinning vehicle on the GPS signal. In rapid spinning vehicles such as missiles and space rockets, carrier phase and frequency depend on the roll rate of the vehicle. It induces phase and frequency modulation caused by the roll rate. The modulated phase and frequency increase dynamic stress error of the tracking loop. Even though higher order tracking loop can remove dynamic stress error, the dynamic stress error can not be remove in this case. In order to analyze the effect of the spinning vehicle on the GPS signal, the experiments are carried out. The experiment results show the modulation of the carrier frequency and phase caused by the roll rate of the spinning vehicle.

• 한국항공우주학회지
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• 제33권6호
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• pp.45-50
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• 2005

GPS 반송파 측정값을 이용하게 되면 수 cm 이하의 정밀도로 위치 결정을 수행 할 수 있으며, 두 개 이상의 안테나를 움직이는 물체에 장착할 경우 정밀한 자세 결정을 수행할 수 있다. GPS 반송파 측정값을 사용하는 경우 항상 미지정수 결정의 어려움이 발생하게 되며, 미지정수 결정 과정에서 올바른 결정을 할 수 있는 척도로 성공확률을 확인할 필요가 있다. 본 논문에서 저궤도 위성의 자세 결정을 위하여 이중차분된 측정값을 사용하게 되며, 이때 만들어진 측정행렬과 측정값의 공분산을 이용하여 성공확률을 계산하게 된다. 성공확률을 향상시키기 위하여 저궤도 위성의 위치벡터와 자세벡터가 수직이라는 제한 조건을 사용하여 측정값을 증가시키는 방법을 제안하였다. 적용된 저궤도 위성의 궤도는 우리별 3호의 궤도 정보를 이용하여 만들었으며 시뮬레이션을 통하여 그 결과를 확인 하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.114.1-114
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• 2001

GPS Receiver gives pseudorange Doppler and integrated carrier phase for measurements to compute navigation information. Thought the integrated carrier phase can be transfer to the equal domain as pseudorange by multiplying the wave length of the received signal, in order to get position information from the carrier phase measurements the integer ambiguity should be resolved. And differencing technique is generally used to eliminate the common error terms of the integrated carrier phase measurements between robber and server. In short baseline double-differencing operation has effect on elimination the common biases for both stations and thus ambiguity resolution are to be reliable. But the baseline increases, the integer ambiguity resolution is hardly, due to the correlated common error is increase ...

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.179-184
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• 2006

Rapid and high-precision positioning with a Global Navigation Satellite System (GNSS) is feasible only when very precise carrier-phase observations can be used. There are two kinds of mathematical models for ambiguity resolution. The first one is based on both pseudorange and carrier phase measurements, and the observation equations are of full rank. The second one is only based on carrier phase measurement, which is a rank-defect model. Though the former is more commonly used, the latter has its own advantage, that is, ambiguity resolution will be freed from the effects of pseudorange multipath. Galileo will be operational. One of the important differences between Galileo and current GPS is that Galileo will provide signals in four frequency bands. With more carrier-phase data available, frequency combinations with long equivalent wavelength can be formed, so Galileo will provide more opportunities for fast and reliable ambiguity resolution than current GPS. This paper tries to investigate phase only fast ambiguity resolution performance with four Galileo frequencies for short baseline. Cascading Ambiguity Resolution (CAR) method with selected optimal frequency combinations and LAMBDA method are used and compared. To validate the resolution, two tests are used and compared. The first one is a ratio test. The second one is lower bound success-rate test. The simulation test results show that, with LAMBDA method, whether with ratio test or lower bound success rate validation criteria, ambiguity can be fixed in several seconds, 8 seconds at most even when 1 sigma of carrier phase noise is 12 mm. While with CAR method, at least about half minute is required even when 1 sigma of carrier phase noise is 3 mm. It shows that LAMBDA method performs obviously better than CAR method.

• 대한공간정보학회지
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• 제9권1호
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• pp.59-66
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• 2001

GPS/GLONASS 결합을 통해 위성의 가시성, 정확성, 그리고 이용성 등이 증가하였다. 하지만 두 시스템 결합에서 시간계 차이, 좌표계 차이, 그리고 GLONASS의 상이한 주파수에 의해 결합 반송파 주파수에서 반송파 미지정수 결정에 관한 문제점을 가지고 있다. 따라서 본 연구에서는 단독위치결정에서 GPS/GLONASS 결합에 의한 위치결정 정확도를 평가하고, GPS/GLONASS 결합에 의한 위성의 가시성과와 위성신호 수신고도각에 따른 자료획득율을 검토함으로써 GPS/GLONASS 결합 특성을 알아보고자 한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.303-306
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• 2006

A roll rate estimation method is proposed using the GPS measurement for spinning vehicles such as guided munitions and smart bombs. Before designing the roll rate estimator, the carrier phase and the carrier frequency deviation caused by spinning have been observed. Based on the observation, the spinning frequency is estimated using I and Q value from the correlator. The proposed method is evaluated through computer simulations using a software defined receiver and a GPS IF signal generator.

• Journal of Astronomy and Space Sciences
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• 제33권1호
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• pp.45-54
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• 2016

This study developed an approach for improving Carrier-phase Differential Global Positioning System (CDGPS) based realtime satellite relative navigation by applying laser baseline measurement data. The robustness against the space operational environment was considered, and a Synthetic Wavelength Interferometer (SWI) algorithm based on a femtosecond laser measurement model was developed. The phase differences between two laser wavelengths were combined to measure precise distance. Generated laser data were used to improve estimation accuracy for the float ambiguity of CDGPS data. Relative navigation simulations in real-time were performed using the extended Kalman filter algorithm. The GPS and laser-combined relative navigation accuracy was compared with GPS-only relative navigation solutions to determine the impact of laser data on relative navigation. In numerical simulations, the success rate of integer ambiguity resolution increased when laser data was added to GPS data. The relative navigational errors also improved five-fold and two-fold, relative to the GPS-only error, for 250 m and 5 km initial relative distances, respectively. The methodology developed in this study is suitable for application to future satellite formation-flying missions.