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研究生:吳嘉富
研究生(外文):Jia-Fu Wu
論文名稱:一種使用啾聲轉換演算法為頻率擷取並應用在GPS接收器的新型快速方法
論文名稱(外文):A NEW FAST FREQUENCY-ACQUISITION TECHNIQUE USING CHIRP TRANSFORM ALGORITHM FOR GPS RECEIVER
指導教授:鄭木火
指導教授(外文):Mu-Huo Cheng
學位類別:碩士
校院名稱:國立交通大學
系所名稱:電機與控制工程系所
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2005
畢業學年度:93
語文別:英文
論文頁數:31
中文關鍵詞:全球定位系統假隨機碼傅立葉轉換法啾聲轉換演算法
外文關鍵詞:GPSPRNFFTCTA
相關次數:
  • 被引用被引用:0
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訊號擷取在全球定位系統 (GPS) 接收器中是一個粗略的同步過程,其目的是估測偽隨機碼(Pseudo-Random Number, PRN)
的延遲和都普勒頻率。 既有文獻中的擷取方法可分為時域法和頻域法。早期的方法是在時域中計算相關函數以達到最大近似估測。
近年來擷取的方法使用快速傅立葉轉換法 (Fast Fourier Transform, FFT) 在頻域中計算相關函數以減少所需計算複雜度。
但即使是使用頻域法若要估測到幾十赫芝解析度之都普勒頻率,其所需的計算複雜度仍相當高。
此乃因為FFT是計算訊號整個頻譜,但所要的都普勒頻率範圍相對於訊號的頻譜來說相當的小。
本論文因此提出利用啾聲轉換演算法 (Chirp Transform Algorithm, CTA)
的方法來克服此問題。主要是利用
CTA 會將所有的運算功能均放在都普勒頻率的頻段上,故可降低計算複雜度或提高頻率解析度。
本論文並將以CTA估測都普勒頻率及以FFT估測PRN碼的相位兩方法相結合,形成一新的訊號擷取方法,稱之為兩階段法。
其與傳統方法相比較,計算複雜度在同一性能下將可降低。
本論文最後以運算複雜度為量測參數,使用電腦模擬來驗証本論文所提方法之優越性。
Signal acquisition in GPS receiver is a coarse synchronization process
whose goal is to estimate the Pseudo-Random Number (PRN) code delay and the Doppler frequency.
The acquisition methods, in literatures, are performed in either time domain or frequency domain.
Early methods compute the correlation in the time domain to achieve
the performance of maximum likelihood estimation (MLE).
Recently, new realization techniques have been developed for
computing the correlation in frequency domain via the fast Fourier transform (FFT)
such that the computation complexity is significantly reduced.
The approaches via the FFT, however, still
require high computation complexity if one desires to
estimate the Doppler frequency with its resolution up to a few
Hertz.
The reason is because the FFT evaluates the whole signal spectrum, but the range of
possible Doppler frequency is relatively much small compared with
the signal spectrum. Therefore, this thesis employs the
Chirp Transform Algorithm (CTA) to overcome this drawback because
the CTA evaluates only within the range of Doppler frequency.
This approach can either reduce the computation complexity or increase the
frequency resolution. In this thesis, we further combine together the two techniques,
one using
the CTA for Doppler frequency estimation and the other using
the FFT for code delay estimation, yielding
a new acquisition approach, referred to as the two-stage search method
which, compared with traditional methods,
can reduce the computation complexity.
Computer simulations are also performed to demonstrate
the advantages of our proposed methods.
ABSTRACT IN CHINESE i
ABSTRACT IN ENGLISH ii
ACKNOWLEDGEMENTS IN CHINESE iii
LIST OF FIGURES vi
LIST OF TABLES viii
1 INTRODUCTION 1
1.1 Introduction . . . . . . . . . . . . . . . . . . 1
1.2 Motive and Literatures Review . . . .. . . . . . 1
1.3 Organization of the Thesis . . . . . . . . . . . 2
2 GPS SIGNAL MODEL 3
2.1 Introduction to GPS . . . . . . . . . . . . . . 3
2.2 GPS Signals From Satellites .. . . . . . . . . . 4
2.2.1 Signal Structure . . . . . . . . . . . . . . . 4
2.2.2 Generation of C/A Code . . . ... . . . . . . . 4
2.3 GPS Receiver . . . . . . . . . . . . . . . . . . 6
2.3.1 RF Module . . . . . . . ...... . . . . . . . . 7
2.3.2 A/D Converters . . . . . . . . . . . . . . . . 8
2.4 Input Signals of The Digital Baseband Processor . 8
3 C/A CODE ACQUISITION 9
3.1 Acquisition Using FFT . . . . . . . . . . . . . . 10
3.1.1 Serial(code delay)-Parallel(Doppler frequency) Method 10
TABLE OF CONTENTS
3.1.2 Parallel(code delay)-Serial(Doppler frequency) Method 11
3.2 Acquisition Using CTA . . .. . . . . . . . . 12
3.2.1 CTA Algorithm [13] . . . . . . . . . . . . 13
3.2.2 CTA Method . . . . . . . . . . . . . . . . 14
3.2.3 Two-stage Search Strategy . . .. . . . . . 15
3.3 Computation Complexity . . . . . . . . . . . 17
4 SIMULATIONS AND DISCUSSIONS 20
5 CONCLUSIONS 29
References 30
1.U. J. Cheng, J. H. William, and I. S. Joseph, ``Spread Spectrum Code Acquisition in the Presence of Doppler Shift and Data Modulation,"
,"IEEE Trans. Commun., Vol. 38, pp. 241-250, 1990.
2.D.J.R Van Nee, and A. J. R. M. Coenen, ``New Fast GPS Code-Acquisition Technique Using FFT
," IEE Electronics Letters, Vol. 27, pp. 158-160, Jan. 1991
3.C. L. Spillard, S. M. Spangenberg, and G. J. R. Povey, ``A Serial-Parallel FFT Correlator of PN Code Acquisition from LEO Satellites
," l Spread Spectrum Techniques and Applications, 1998. Proceedings., 1998 IEEE 5th International Symposium on
, Vol. 2, pp. 446-448, Sept. 1998

4.Y. F. Liu, Z. J. Chen, and S. L. Gus, ``Implement and Performance Analysis of PN Code Acquisition Based on FFT,"
sl Proceedings of the 5th World Congress on Intelligent Control and Automation, pp. 5399-5401 June, 2004.
5.J. Starzyk and Z. Zhu, ``Averaging Correlation for C/A Code Acquisition and Tracking in Frequency Domain," IEEE MWSCS, Fairborn, Ohio, Aug. 2001.

6.A. Alaqeeli, J. Starzyk, and F. Van Graas, ``Real-Time Acquisition and Tracking for GPS Receivers," Circuits and Systems, 2003. ISCAS '03. Proceedings of the 2003 International Symposium,
Vol. 4, pp. IV-500-IV-503, May 2003.
7.D. N. Fernaado and M. N. L. Jose, ``A New Fast Code/Frequency Acquisition Algorithm for GPS C/A Signals," Vehicular Technology Conference, 2003. VTC 2003-Fall. 2003 IEEE 58th,
Vol. 2, pp. 766-770, Oct. 2003.
8.J. B.-Y. Tsui, sl Fundamentals of Global Positioning System Receivers, A Software Approach, Wiley, New York, 2000.
9.``Global Positioning System Standard Positioning Service Signal Specification," 2nd edition, GPS Joint Program Office, Jan. 1995.
10.W. H. Zhuang, ``Composite GPS Receiver Modeling, Simulations and Applications," Ph.D dissertation, Department of Electrical
Engineering, University of New Brunswick, Fredericton, Oct. 1992.
11.W. H. Zhuang and J. Tranquilla,
``Digital Baseband Processor for the GPS Receiver - Modeling and Simulations,"
IEEE Trans. on Aerospace and Electronic Systems, Vol. 29, pp. 1343-1349, Oct. 1993.
12.W. J. Hurd, J. I. Statman, and V. A. Vilnrotter,
``High Dynamic GPS Receiver Using Maximum Likelihood Estimation and Frequency Tracking,"
IEEE Trans. on Aerospace and Electronic Systems, Vol. 23, pp. 425-437, July 1987.
13.A. V. Oppenheim, R. W. Schafer, and J. R. Buck,
Discrete Time Signal Processing,
Prentice Hall International Editions, second edition, 1999.
14.J. B. Thomas,
``Functional Description of Signal Processing in the Rogue GPS Receiver,"
JPL Publication, 88-15, Pasadena, California, June 1988.
15.J. J. Spilker,
``GPS Signal Structure And Performance Characteristics,"
Navigation, Institute of Navigation, Vol. 25, No. 2, pp. 121-146, 1978.
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