張帆人毛偉龍臺灣大學：陳韋佑Chen, Wei-YuWei-YuChen2007-11-262018-07-062007-11-262018-07-062007http://ntur.lib.ntu.edu.tw//handle/246246/53486全球定位系統(GPS)可在各種導航、時頻同步等工程應用領域提供精確的位置與時間資訊。GPS雖能藉由展頻碼的程序增益，來抵抗一些寬頻的干擾(如熱雜訊與通道雜訊)或是低能量的窄頻干擾，但其仍無法應付更高能量的干擾，因此GPS接收機的干擾抑制研究，已成為一重要且實際的課題。 在本論文中，所探討的干擾訊號是調頻干擾。由於調頻干擾之頻率會隨著時間進行而改變，所以必須利用時頻分析方法偵測干擾的特性。時頻分析方法包含了短時傅立葉轉換(Short Time Fourier Transform, STFT)、蓋博轉換(Gabor Transform)、魏格納分佈(Wigner Distribution)及希爾伯特-黃轉換(Hilbert-Huang Transform, HHT)。經由模擬與比較得知HHT具有較佳的時頻解析度，所以我們運用HHT來呈現GPS調頻干擾的抑制效果。這個方法是以稱為經驗模態分解(EMD)的方式產生一組本質模態函數(IMF)為基礎。我們將最大能量的IMF當作是干擾並且將它移除。 接著，我們將利用弦波調頻干擾及線性調頻干擾作為干擾抑制之測試。經過軟體模擬可知在HHT的架構下，對於窄頻的調頻干擾已有不錯的抑制效果，且對於寬頻調頻干擾而言也能偵測出干擾源的特性。整體干擾抑制之效能較之前相關的研究提升許多。The global position system (GPS) can provide accurate positioning and timing information in many applications. GPS can cope with wideband noise (such as thermal noise and channel noise) or low power narrowband interference with the processing gain of spreading code. However, GPS cannot reject high power interference completely. Therefore, interference suppression research of GPS receiver has become an important issue. In this thesis, we consider interference source as frequency modulation interference. Because frequency modulation interference is time-varying interference signal, we apply time-frequency analysis to detect characteristics of interference. The ways to analyze time-frequency include Short Time Fourier Transform (STFT), Gabor Transform, Wigner Distribution, and Hilbert-Huang Transform (HHT). Because Hilbert-Huang Transform has the best time-frequency resolution, we use HHT to simulate the performance of frequency modulation interference suppression. It is based on the empirical mode decomposition (EMD), which generates a set of intrinsic mode functions (IMF). We take the IMF which has the biggest energy as interference and remove it. Then, we use sinusoidal frequency modulation interference and linear frequency modulation interference to perform interference suppression test. Through software simulation, under HHT frame we can get excellent interference suppression result for narrowband frequency modulation interference and can detect interference characteristics for wideband frequency modulation interference. Compare to the previous research, the interference suppression ability in this research is superior.第一章 序論.......1 1.1 研究動機......1 1.2 研究方向......1 1.3 論文組織......4 第二章 GPS訊號特性與接收機架構.......5 2.1 GPS訊號產生流程......5 2.2 GPS電碼特性......6 2.3 GPS訊號與雜訊強度分析......12 2.4 GPS接收機系統架構......14 第三章 時頻分析方法介紹及模擬分析.......17 3.1 基本概念......17 3.1.1 瞬時頻率(Instantaneous Frequency)......19 3.1.2 測不準原理(Uncertainty Principle)......24 3.2 以傳統傅立業轉換為基礎之時頻分析方法......25 3.2.1 Short Time Fourier Transform (STFT)定義及性質......25 3.2.2 Gabor Transform定義及性質......26 3.2.3 Wigner Distribution定義及性質......27 3.3 Hilbert-Huang Transform (HHT).......29 3.3.1 技術發展背景......29 3.3.2 本質模態函數(Intrinsic Mode Function)......29 3.3.3 經驗模態分解(Empirical Mode Decomposition)......30 3.4各分析方法模擬與比較......33 第四章 調頻干擾抑制之模擬.......37 4.1 模擬環境之設定......37 4.2 干擾抑制效能評估方法......42 4.3 模擬結果......44 4.3.1 弦波調頻干擾之測試......44 4.3.2 線性調頻干擾之測試......56 第五章 結論與未來展望.......69 5.1 結論......69 5.2 未來展望......69 參考文獻.......71 附錄A 測不準原理之證明.......73 附錄B 透過經驗模態分解(EMD)分析白高斯雜訊的特性.......75 附錄C 利用重疊快速傅立葉轉換進行調頻干擾抑制之模擬與比較.......811352103 bytesapplication/pdfen-US希爾伯特-黃轉換、干擾抑制、時頻分析、調頻訊號、GPS接收機Hilbert-Huang Transform, Interference Suppression, Time-Frequency Analysis, Frequency Modulation Signal, GPS Receiverthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/53486/1/ntu-96-R94921003-1.pdf