• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.280-287
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• 2006

Advent of the new European satellite positioning system, Galileo will result in development of new satellite receivers such as, GPS/Galileo dual mode receiver. Furthermore, a new GNSS satellite receiver would be required to be self-reconfigured to certain navigational environments like, indoor, high interference, integrity, etc. In this paper, design and implementation issue of a FPGA based flexible GNSS receiver which gets navigation solution using L1 band signals of GPS and Galileo simultaneously is addressed.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.185-185
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• 2000

This paper designs an interference mitigation filter for GPS receiver using a time-domain signal processing techniques (Adaptive Transversal filter). ATF is designed using verilog and simulated using COSSAP for evaluating its performance.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.97-97
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• 2000

In this paper, a signal processing algorithm for software GPS receiver is proposed. The signal processor takes snapshot of the sampled If signal from the RF section of the GPS receiver. All the processing for code and carrier tracking and correlation are implemented using the digital signal processing techniques. In order to achieve fast code acquisition, correlation of the incoming GPS signal is performed using the FFT method, After code acquisition, to reduce the Doppler shift effect and increase the accuracy, the interpolation or the tracking are performed. The performance of the proposed processing algorithm is first evaluated using matlab/simulink. A signal acquisition board for sampling and logging GPS IF signal form the Mitel GPS RF chip set is constructed. In order to analyze the performance of the designed algorithm the experiments are performed and the results are analyzed.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.8
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• pp.752-758
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• 2006

A GPS receiver provides much information such as calculated position, speed, heading, status of satellites, current time errors, etc. It is well-known that GPS signals from GPS receiver mounted on moving vehicle are often distorted, contaminated by various noises, and blocked by tunnel or tall buildings. The phenomenon often obstructs correct navigation especially when a vehicle keeps stopping or is moving in low speed. Therefore it is needed to pre-process the signals to adapt it to various applications. In this paper, an algorithm to pre-process the signals is proposed. For this, GPS data obtaining from uNAV GPS receiver are analyzed and classified based on dynamic characteristic. Then, the proposed algorithm is applied to the data and some test results are shown to verify the usefulness of the algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.494-502
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• 2001

GPS(Global Positioning System) and GLONASS(GLObal Navigation Satellite System) are basic technologies providing the information of the position and the time, and they have various applications such as navigation, survey, control, and so on. However, each GPS and GLONASS has limited number of visible satellites, and, from the view of strategy, it is undesirable to be heavily dependent on only one system. Thus, GPS/GLONASS combined receiver became required to obtain more precise navigation and system stability. In this paper, the RF front end of GPS/GLONASS combined receiver was fabricated on 130$\times$80 $\textrm{mm}^2$ PCB(Printed Circuit Board), and its system application was shown finally one chip possibility of GLONASS receiver is studied.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.64-72
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• 2013

This paper describes the analysis of the tracking and navigation performance of a GPS receiver in a launch vehicle simulation when the carrier tracking loop is designed as a 3rd order phase-locked loop with variable bandwidths. There are differences of tracking and navigation performance according to the variable bandwidths under the dynamics condition. When the bandwidth is set to narrow, the GPS receiver could not track the satellite signals so that the navigation information could not be calculated.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.394-396
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• 2006

When developing a new GPS receiver module, the essential problems are evaluation of reliable algorithms, software debugging, and performance comparison between algorithms to find optimal solution. Most GPS receiver modules nowadays use a correlator to track signals from satellites and an MCU (Micro Controller Unit) to control operations of the entire module. The problem of software evaluation from MCU is very difficult, due to limitation of MCU resources and low ability of interfacing with user. Normally, user has to expense special tool kit for a limiting access to MCU but it is also hard to use. This article introduces an implementation of a GPS receiver test bed using correlator GP2021 interfacing with ISA (Industry Standard Architecture) PC bus. This way can give user complete control and visibility into the operation of the receiver, then user can easily debug program and test algorithms. For this article, the least square method is implemented to test the hardware and software performance.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.2
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• pp.195-206
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• 1997

By this time, in order to measure baseline in a few minutes, we must have used expensive dual frequency receiver. Recently, low-priced single frequency receiver have taken place of dual frequency receiver at short base-line by advancement in software development, improvements in geodetic survey receiver system. In this study, according to the observation time and measurement interval, we analyzed differences of each components of baseline by field experiment and we propose the criterion for the minor control point surveying by single frequency GPS receiver.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.6_1
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• pp.537-543
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• 2007

Since the GPS absolute positioning with pseudorange measurements can significantly be affected by the observation error, the time series analysis of the GPS receiver clock errors was performed in this study. From the estimated receiver clock errors, the time series model is generated, and constrained back in the absolute positioning process. One of the CORS (Continuously Operating Reference Stations) network is used to analyze the behavior of the receiver clock. The dominant part of the model is the linear trend during 24 hours, and the seasonal component is also estimated. After constraining the modeled receiver clock errors, the estimated position error compared to the published coordinates is improved from ${\pm}11.4\;m\;to\;{\pm}9.5\;m$ in 3D RMS.

• Journal of Astronomy and Space Sciences
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• v.28 no.1
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• pp.55-62
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• 2011

The precise orbit determination (POD) of low earth orbiter (LEO) has complied with its required positioning accuracy by the double-differencing of observations between International GNSS Service (IGS) and LEO to eliminate the common clock error of the global positioning system (GPS) satellites and receiver. Using this method, we also have achieved the 1 m positioning accuracy of Korea Multi-Purpose Satellite (KOMPSAT)-2. However double-differencing POD has huge load of processing the global network of lots of ground stations because LEO turns around the Earth with rapid velocity. And both the centimeter accuracy and the near real time (NRT) processing have been needed in the LEO POD applications--atmospheric sounding or urgent image processing--as well as the surveying. An alternative to differential GPS for high accuracy NRT POD is precise point positioning (PPP) to use measurements from one satellite receiver only, to replace the broadcast navigation message with precise post processed values from IGS, and to have phase measurements of dual frequency GPS receiver. PPP can obtain positioning accuracy comparable to that of differential positioning. KOMPSAT-5 has a precise dual frequency GPS flight receiver (integrated GPS and occultation receiver, IGOR) to satisfy the accuracy requirements of 20 cm positioning accuracy for highly precise synthetic aperture radar image processing and to collect GPS radio occultation measurements for atmospheric sounding. In this paper we obtained about 3-5 cm positioning accuracies using the real GPS data of the Gravity Recover and Climate Experiment (GRACE) satellites loaded the Blackjack receiver, a predecessor of IGOR. And it is important to reduce the latency of orbit determination processing in the NRT POD. This latency is determined as the volume of GPS measurements. Thus changing the sampling intervals, we show their latency to able to reduce without the precision degradation as the assessment of their precision.