• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.1
• /
• pp.7-12
• /
• 2008

A GNSS(Global Navigation Satellite System) using GPS provides us with very useful information concerning the positioning of users in many sectors such as transportation, social services, the justice system and customs services, public works, search and rescue systems and leisure. A GNSS using the Galileo satellite is due to work in 2008 and expected to be used in various fields such as aviation, marine transportation, land surveying, resources development precise agriculture, telemetics, and so on. In this paper, we discuss the implementation and testing of a combined GPS/Galileo receiver which we named KSTAR V1.0. Each tracking module of GPS/Galileo dual mode correlator has the five track arms which consist of Very Early code, Early code, Prompt code, late code, and Very late code. Each of 24 tracking modules can be assigned to GPS and/or Galileo signal by changing mode selection register. The basic correlator integration dump period is set to 1ms for GPS C/A code and fast Galileo signal tracking. The performance of the developed combined GPS/Galileo receiver was tested and evaluated using the IF (Intermediated Frequency)-level GPS/Galileo signal generator.

• Journal of Satellite, Information and Communications
• /
• v.6 no.1
• /
• pp.68-74
• /
• 2011

In this paper, we present the enhancement results such as availability and accuracy using the GPS L1 and Galileo E1 signal combination. To enhance the acquisition and tracking performance of signal processing in GNSS receiver. several tracking loops with integrator, discriminator, and loop filter module are applied. Also, this paper presents the performance comparison results between prototype receiver equipped with hardware board and software receiver. Also the tracking loop performance of real hardware receiver is verified by comparing with tracking accuracy, sensitivity occurred by the Spirent simulator. Especially, to process the Galileo E1 signal, it is used the a power early late type which is the typical type for DLL discriminator.

• Journal of Astronomy and Space Sciences
• /
• v.25 no.3
• /
• pp.291-298
• /
• 2008

With the growth of civil and commercial applications, the Global Navigation Satellite System(GNSS) that provides the positioning, navigation, and timing information affects to our life. In order to meet all the requirements of civilian user, new positioning technology with the accuracy of 10cm level has been applied and the positioning accuracy is getting improved. In this study, dual coverage(DAEJ, SUWN) GPS measurements were applied to improve the positioning accuracy for GPS L1 single frequency users. We processed some GPS data obtained from the distributed test sites in the wide area over Korea Peninsula. As a result, the combined solution output using dual coverage showed more improved positioning accuracy than that of single coverage.

• Journal of Astronomy and Space Sciences
• /
• v.14 no.2
• /
• pp.347-354
• /
• 1997

We developed a GPS phase data processing S/W system which calculates baseline vectors and distances between two points located in the surface of the Earth. For this development a Double-Difference mothod and L1 carrier phase data from GPS(Global positioning System) were used. This S/W system consists of four main parts: satellite position calculation, Single-Difference equation, Double-Difference equation, and correlation. To verify our S/W, we fixed KAO($N36^{circ}.37,E127^{circ}.37,H77.61m$), one of the International GPS Services for Geodynamics, which is located at Tae-Jon, and we measured baseline vectors and relative distances with data from observations at approximate baseline distances of 2.7, 42.1, 81.1, 146.6km. Then we compared the vectors and distances with the data which we obtained from the GPSurvey S/W system, with the L1/L2 ION-Free method and broadcast ephemeris. From the comparison of the vectors and distances with the data from the GPSurvey S/W system, we found baseline vectors X, Y, Z and baseline distances matched well within the extent of 50cm and 10cm, respectively.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2011.06a
• /
• pp.319-320
• /
• 2011

이 연구에서는 국토해양부 해양교통시설과 위성항법중앙사무소가 운영하고 있는 DGNSS 기준국의 신호수신환경을 파악하기 위해 관측자료의 TEQC 품질평가와 현장조사를 병행하였다. TEQC는 GPS 수신기로 관측한 원시자료를 RINEX형식으로 변환 편집하고, 관측자료의 품질을 점검하는데 이용하는 GPS 전처리 소프트웨어이다. TEQC 품질점검 기능을 통해 GPS 관측자료의 데이터수신율, L1과 L2 신호의 의사거리 다중경로오차, 사이클슬립에 관한 지수를 산출하였고, 이를 현장조사결과와 상호 비교하였다. 장기 관측 자료의 TEQC 품질지수 결과를 통하여 시간변화에 따른 관측소의 주변환경 및 장비변화 시점을 간접적으로 확인하였다.

• Journal of IKEEE
• /
• v.24 no.2
• /
• pp.649-653
• /
• 2020

GPS is a representative satellite navigation system that provides users with accurate location and time information. GPS L1 C / A is opened for civilian and thus utilized in various fields. When the satellite signal reaches the receiver, signal acquisition unit of the digital signal processing hardware searches and acquires the signal among visible satellites. The signal acquisition unit has different implementation methods depending on the signal searching method, such as serial search acquisition, parallel frequency search, parallel code phase search. In this paper, we compare and analyze the three representative acquisition hardwares using live GPS L1 C/A signals. According to the comparison, the parallel code phase search acquisition outperforms the other methods due to reduction of the number of the searchings and a high resolution.

• Journal of Advanced Navigation Technology
• /
• v.18 no.1
• /
• pp.7-13
• /
• 2014

In this paper, an effect on a GPS receiver by spoofing signal is analyzed and a GPS spoofing signal detection algorithm for GPS L1 C/A spoofing signal is proposed. A proposed detection algorithm monitors the correlation function distortion by the spoofing signal. If detected distortion is over a detection threshold, we can determine that the spoofing signal is received. The detection threshold is calculated from the statistical characteristics of a thermal noise. For verifying the suggested algorithm, a MATLAB-based simulation platform is implemented. This platform has functionalities to track GPS signal and measure the correlation values. By using this platform, the correlation function distortion by spoofing signal is observed. Also a performance of the algorithm proposed in this paper is applied and confirm the detection of a spoofing signal.

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

• Journal of Astronomy and Space Sciences
• /
• v.21 no.4
• /
• pp.371-382
• /
• 2004

To improve the precision of relative positioning for GPS single frequency(L1) receiver, we accomplished the GPS data processing using the weighted smoothing techniques. The weighted phase smoothing technique is used to minimize the measurement error of pseudorange and position domain smoothing technique is adopted to make the complement of cycle-slip affection. we also considered some component errors like as ionospheric error, which are related with baseline length, and processed for several baselines (5, 10, 30, 40, and 150 km) to check the coverage area of this algorithm. This paper shows that weighted phase smoothing technique give more stable results after using this technique and the position domain smoothing technique can reduce the errors which are sensitive to the observational environment. Based on the results, we could find out that this algorithm is available for post-time and real-time applications and these techniques can be substitution methods which is able to get the high accuracy and precision without resolving the Integer ambiguity.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.1
• /
• pp.61-68
• /
• 2017

In this paper, the coarse acquisition code (C/A code), for civil navigation, of the ranging codes for Global Positioning System (GPS) is studied, simulated and analyzed by using Matlab. We can see with the simulation results that the correctness of the method and feasibility, which is at simulation platform to further study on the real environment of GPS signal, can be confirmed. With using this results, we think, the complexity of tracking the satellite signal environment can be captured, and the performance of satellite receiver will be improved.