臺灣博碩士論文加值系統

近來衛星通訊已廣泛用於大眾的生活上，特別是應用於廣播上。由於衛星通訊是採用較高的頻率來傳送資訊，以至於有較大的頻寬可以傳送越來越大量的多媒體資訊的需求。
經過本實驗室多位學長的研究與努力下，終於完成了中華衛星一號Ka頻帶通道的模擬程式。目前所剩的任務就是去利用實驗的結果來驗證此模擬程式的結果是否與真實的中華衛星一號通道特性相符。此任務的完成必須仰賴大量的資量處理與比對的工作。由於之前所建立的Ka頻帶模擬程式沒有建立中華衛星的軌道，因此必須再跑模擬程式前先作一些處理，其目的是為了得到中華衛星的相關資訊。造成之前的模擬流程因為這些事前的準備工作而變的非常的複雜與耗時。為了可以減少模擬有需要的時間，唯有自己建立一套衛星軌道模型以預測軌道資訊才是根本的解決之道。也唯有如此，整個模擬及比對的流程才得以被簡化，而所需的時間方能減少到最低。
中華衛星一號與地球之間的關係可以利用一些基本的天文動力學推導出來。在介紹整個理論及解決問題的方法和技巧之後，將完整的描述軌道預測的演算法和流程並將結果與NASA的SGP4模型作比較。在軌道模型整合到Ka頻道模擬程式後，整個模擬及比對的流程的改變會在後頭敘述，並展示利用此流程所得到的一些結果。此後的工作將會依照此新的流程來進行。

Nowadays, satellite communication is commonly used for civilians, especially in the broadcasting area. By using higher frequency bands in satellite communication, it has advantage of broader bandwidth to transmit more mounts of multimedia data required by human activity.
After lots of team efforts, the Ka-band simulation program was built. It now remains to verify whether the simulation results are close to real channel via ROCSAT-1 or not. This task can be only be accomplished with great mount of data processing and comparison. Since the existing Ka-band simulation program doesn’t include the orbit model of ROCSAT-1, it is necessary to run some pre-simulation to get the orbit information of ROCSAT-1. Therefore, the existing procedure of running simulation is very complicated and consumes lots of time. In order to reduce the time of simulation, it is necessary to build orbit model of ROCSAT-1 of our own. Thus, the whole procedure of simulation could be simplified. And the time of simulation can be reduced to the least.
The main relationship between ROCSAT-1 and the Earth is deduced by fundamental dynamics. After describing the whole theory of two-body mechanics, the technique to simplify and solve the problem will also be introduced. Next, The whole algorithm of orbit prediction will be described in detail and be compared with the SGP4 model. The whole procedure of simulation with orbit model integrated into the Ka-band simulation program will be described subsequently and followed by the simulation results using this new procedure. From now on, all works will be processed using this new procedure.

Chapter 1. Introduction……………………………………………………………1
1.1. Overview of Direct Broadcast Experiments via ROCSAT-1……………1
1.2. Thesis Organization………………………………………………………4
Chapter 2. Coordination and Time System………………………………………5
2.1. Coordinate System………………………………………………………5
2.1.1. The Geocentric-Equatorial Coordinate System…………………………6
2.1.2. The Right Ascension-Declination Coordinate System…………………6
2.1.3. The Body-Fixed Coordinate System……………………………………7
2.1.4. The Perifocal Coordinate System………………………………………7
2.1.5. The Topocentric-Horizon Coordinate System………………………….8
2.2. Coordinate Transformation………………………………………………9
2.2.1. Transformation Between XYZ and PQH………………………………9
2.2.2. Transformation Between XYZ and SEU………………………………11
2.3. Orbit Elements…………………………………………………………12
2.4. Time and Calendar……………………………………………………13
2.4.1. Time……………………………………………………………………14
2.4.2. Calendar………………………………………………………………15
Chapter 3. Two-Body Mechanics…………………………………………………17
3.1. Fundamental Dynamics…………………………………………………17
3.2. The Elliptical Orbit……………………………………………………20
3.2.1. Geometry of The Ellipse………………………………………………21
3.2.2. Period of an Elliptical Orbit……………………………………………22
3.3. Flight as Function of Time……………………………………………24
3.3.1. Position and Velocity in Terms of True Anomaly……………………24
3.3.2. Anomaly as Function of Time…………………………………………25
3.4. Physical Effect and Perturbations………………………………………26
3.4.1. The Ellipsoid Model of the Earth………………………………………26
3.4.2. Perturbation…………………………………………………………… 27
Chapter 4. Simulation on Orbit Prediction……………………………………32
4.1. Algorithm and Procedure of Orbit Prediction…………………………32
4.2. Simulation Results………………………………………………………39
4.3. The Procedure of Ka-band Simulation and Comparison………………45
Chapter 5. Conclusion…………………………………………………………52
Appendix A. Format of Two-Line Element File………………………………53
Appendix B. Newton-Raphson Method…………………………………………56
Appendix C. Constants…………………………………………………………...58
Reference…………………………………………………………………………….59

[1] J. F. Kiang, “Direct Broadcast Simulation o Digital TV Signals”, quarterly report to NSPO, February, 1998.
[2] Yi-Jeng Liau, “Simulation & Preliminary Verification of Direct Broadcast Experiments via ROCSAT-1”, Master Thesis, National Tsing-Hua University, 2000.
[3] Bate, Roger R./Mueller, Donald D.,/White, Jerry E., "Fundamentals of Astrodynamics," New York :The McGraw-Hill Companies, Inc.,1971.
[4] David A. Vallado, “Fundamentals of Astrodynamics and Applocations ”, 2nd Ed., Space Technology Library, 2001.
[5] George W. Collins, II, “The Foundations of Celestial Mechanics”, Pachart Pulishing House, 1989.
[6] P. Kenneth Seidelmann, “Explanatory Dupplement to the Astronomical Almanac”, University Science Books, 1992.
[7] Dan Boulet, “Method of Orbit Determination for the Micro Computer”, Willmann-Bell, Inc., 1991.
[8] Felix R. Hoots, Ronald L. Roehrich, “Spacetrack Report NO.3”, 1988.
[9] William H. Press, Saul A. Teukolsky, William T. Vetterling, Brian P. Flannery, “Numerical recipes in C”, 2nd Ed., Cambridge University Press, 1992.