• Title/Summary/Keyword: GPS P(Y) code

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Analysis of Coarse Acquisition Code Generation Algorithm in GPS System (GPS 시스템의 C/A 부호 생성 알고리듬의 분석)

  • Zhang, Wei;Suh, Hee-Jong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.12 no.1
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    • pp.61-68
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    • 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.

GPS Jamming Techniques and Anti-Jamming GPS Technologies (GPS 재밍 기법과 항재밍 GPS 기술)

  • Jo, In-hwa;Kim, Hyeong-suk;Park, Tae-yong
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.10a
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    • pp.573-575
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    • 2015
  • Positioning system using satellite GPS is used at positioning, navigation, acquisition time information and other various field and taking an important part precision guided weapon such as missile. But commercial code(C/A code) do not have ECCM. Therefore commercial code is vulnerable to various jamming techniques and noise jamming from near station can attack even the encrypted military code(P code) GPS. In this paper, GPS jamming techniques, North Korean GPS jamming cases and anti-jamming GP S technologies are surveyed and described.

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Technical Issues on Implementation of GPS Signal Authentication System

  • So, Hyoungmin;Jang, Jaegyu;Lee, Kihoon;Park, Junpyo
    • Journal of Positioning, Navigation, and Timing
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    • v.7 no.3
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    • pp.139-146
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    • 2018
  • In recent years, a satellite navigation signal authentication technique has been introduced to determine the spoofing of commercial C/A code using the cross-correlation mode of GPS P(Y) code received at two receivers. This paper discusses the technical considerations in the implementation and application of authentication system simulator hardware to achieve the above technique. The configuration of the simulator consists of authentication system and user receiver. The synchronization of GPS signals received at two devices, data transmission and reception, and codeless correlation of P(Y) code were implemented. The simulation test result verified that spoofing detection using P(Y) codeless correlation could be achieved.

Performance Comparison of Different GPS L-Band Dual-Frequency Signal Processing Technologies

  • Kim, Hyeong-Pil;Jeong, Jin-Ho;Won, Jong-Hoon
    • Journal of Positioning, Navigation, and Timing
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    • v.7 no.1
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    • pp.1-14
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    • 2018
  • The Global Positioning System (GPS) provides more accurate positioning estimation performance by processing L1 and L2 signals simultaneously through dual frequency signal processing technology at the L-band rather than using only L1 signal. However, if anti-spoofing (AS) mode is run at the GPS, the precision (P) code in L2 signal is encrypted to Y code (or P(Y) code). Thus, dual frequency signal processing can be done only when the effect of P(Y) code is eliminated through the L2 signal processing technology. To do this, a codeless technique or semi-codeless technique that can acquire phase measurement information of L2 signal without information about W code should be employed. In this regard, this paper implements L2 signal processing technology where two typical codeless techniques and four typical semi-codeless techniques of previous studies are applied and compares their performances to discuss the optimal technique selection according to implementation environments and constraints.

Precise Static Positioning with Dual-Frequency P-code/Phase Receivers in Global Positioning System (GPS위성의 P코드/위상측정용 2주파수 수신기에 의한 정밀측위)

  • Lee, Young Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.2
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    • pp.219-228
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    • 1993
  • The development of the Global Positioning System was one of the most significant technical advancements in the surveying fields during the 1980's. In recent years, the use of GPS techniques are increased because of the improvements of receiver design and the data analysis, and the greater accuracy. In this paper, the static positioning with special linear combinations of data is reviewed and some experiences of dual-frequency P-code/phase receivers are discussed. The test results of Wild GPS System-200 show that the highest accuracies of 1ppm are obtainable on baselines of 7km/37km and the positional accuracies of 10m, which is applicable to determination of initial coordinates, are also possible on point-positioning of P-code measurements.

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Simulation of GNSS Spoofing Detection Method Using Encrypted Ranging Signal (암호화 신호원을 이용한 위성항법 기만 검출기법 모의)

  • So, Hyoungmin
    • Journal of Advanced Navigation Technology
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    • v.20 no.5
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    • pp.394-400
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    • 2016
  • It is well known that the encrypted ranging signal, such as GPS P(Y) code, is immune to spoofing attack. However, in order for users to use the signal, there needs permission from the operator. And also there are many restrictions for use because of security issues. In this paper, a ground reference station equipped with high-gain directional antenna and a user receiver were simulated. In the reference station, the encrypted code can be demodulated from the high-gain signal. And then the code can be used to detect spoofing attack in the user receiver. This paper proposes the spoofing detection method using the encrypted signal and deals with simulation results.

GNSS 이용 시각비교 통합 모니터링

  • Kim, Jun-Hwan;Yang, Seong-Hun;Lee, Yeong-Gyu;Lee, Seung-U;Lee, Chang-Bok;Kim, Gi-Du
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.2
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    • pp.482-485
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    • 2006
  • 다채널 시각비교 수신기(R100-40T, Euro-80)를 이용한 GPS C/A 코드 시각비교 데이터와 Ashtech Z12T 수신기를 이용한 P3 코드 시각비교 데이터를 통합 모니터링함으로서, 간편하게 시각비교 결과를 확인 할 수 있게 GUI(Graphic User Interface) 환경으로 구현하였다. 수신기들은 현재 KRISS(Korea Research Institute of Standards and Science)에서 사용 중인 위성이용 시각비교 수신기들이다. 본 시각비교 통합 모니터링 프로세스를 통해서 GPS C/A code 시각비교 데이터와 P3 code 시각비교 데이터 각각을 비교 분석함으로써 시각비교 결과의 신뢰성을 검증하는데 사용한다.

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THE MEASUREMENT OF THE IONOSPHERIC TOTAL ELECTRON CONTENT USING P-CODE OF GPS (GPS의 P 코드를 이용한 이온층의 총전자수 측정)

  • 서윤경;박필호;박종욱;이동훈
    • Journal of Astronomy and Space Sciences
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    • v.11 no.1
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    • pp.71-80
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    • 1994
  • It is generally known that the measurement of the ionospheric total electron content(TEC) by GPS can more accurately monitor the broader area of the ionosphere than other current methods. \Ve measured the TEC along a slant path considering the arrival time differences of P-code which is transmitted from GPS satellites with the modulation on two L-band carrier frequencies, L1 (1574.42MHz) and L2 (1227.60MHz). Under the assumptions that the ionosphere is uniformly distributed and its average height is 350km, we transformed the slant TEC to the vertical TEC at the point that the line-of-sight direction to GPS satellite cut across the average height of the ionosphere. Because there is no dual frequency P-code GPS receiver in Korea, we used the data observed at the TAIW GPS station ($N25^{\circ},E121.5^{\circ}$) in Taiwan which is one of the core stations in International GPS and Geodynamics Services (IGS). The TEC values obtained in this work showed a typical daily variation of the ionosphere which is high in the daytime and low in the nighttime. Our results are found to be consistent with the SOLAR-DAILY data of NOAA and the Klobuchar's model for the ionospheric correction of GPS. In addition, in the cornparision with SOLAR-DAILY data, we estimated the precision of our TEC measurement as 2 TEC.

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Delayed Parallel Interference Cancellation for GPS C/A Code Receivers

  • Glennon, Eamonn P.;Bryant, Roderick C.;Dempster, Andrew G.
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.2
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    • pp.261-266
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    • 2006
  • A number of different techniques are available to mitigate the problem of cross correlations caused by the limited dynamic range of the 10-bit Gold codes in the GPS C/A code. These techniques include successive-interference cancellation (SIC) and parallel-interference cancellation (PIC), where the strong signals are subtracted at IF prior to attempting to detect the weak signals. In this paper, a variation of these techniques is proposed whereby the subtraction process is delayed until after the correlation process, although still employing a pure reconstructed C/A code signal to permit prediction of the cross correlation process. The paper provides details on the method as well as showing the results obtained when the method was implemented using a software GPS receiver. The benefits of this approach are also described, as is the application of the method to the cancellation of CW interference.

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