| The Reduction of the Searching Candidates for the GPS Signal Acquisition |
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| GPS 초기 동기를 위한 탐색 후보 축소 |
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서흥석, 강설묵, 이상정 |
1충남대학교 전자공학과 대학원
2국방과학연구소
3충남대학교 정보통신공학부 |
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| Abstract |
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A 2-dimensional search process in the time and frequency domain is required to acquire the GPS signal, when the code phase and the carrier Doppler for the specified GPS satellite signal are unknown. This paper proposes a new scheme, called Squared-D Searching Method, which can reduce the number of carrier frequency candidates, and a new scheme, named extended Multiple Correlator(XMC), which can reduce the number of code phase candidates. The Squared-D Searching Method can take the twice of Doppler frequency, therefore it can find carrier frequency candidates. The XMC is different from the general multiple correlator in that a combined form of the locally generated codes is used for despreading. Also, this paper tries to analyze a signal detection probability of a GPS receiver under more realistic environments. The result shows that lower detection probability can be obtained when the phase differences among the codes are larger in the correlation arms of a multiple correlator. This phenomenon is not easy to explain with the previous results. And besides, the result shows that proposed acquisition schemes give better performance than a conventional acquisition scheme. |
| Key Words:
Fast Acquisition, Signal Processing, Extended Multiple Correlator, Squared-D Searching Method |
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