臺灣博碩士論文加值系統

跳頻通訊為軍方保密通訊的重要手段，針對此一通訊方式之電子反制技術益顯重要。掌握敵方通信機參數，將有助於我方更有效率遂行干擾與電子反制作為；還原敵方傳送之訊息或語音，對軍事情報搜集，將有極大之助益。有關跳頻通信之相關反制技術，因屬國防科技之範疇，各國研究成果甚少公開。現有文獻皆以跳頻通信為主軸，研究如何抗干擾及保密通信；以反制的觀點，探討截收竊聽技術的文獻相對偏少。
本論文主要以反制之觀點，探討在不明白通訊雙方跳頻信號的同步機制下，運用短時傅立葉轉換(STFT, Short-Time Fourier Transform)作為跳頻信號時頻域分析之工具，設計一跳頻通信解調機制，針對慢速跳頻(SFH, Slow Frequency-Hopping)M進制頻移鍵送(MFSK, M-ary Frequency Shift Keying)信號及調頻(FM, Frequency Modulation)號進行截收、估測及解調。
經由電腦軟體模擬驗證，本論文提出之跳頻通信截收機架構，確可估測出跳頻信號使用頻率、跳頻週期、信符週期、M進制值等跳頻信號相關參數，不僅可以軟體方式實現離線(Off-Line)截收解調，亦可做為硬體實現線上(On-Line)截收解調之參考。

Frequency Hopping (FH) is an important technique in secret communication of military usage. The electronic counter technologies for FH communications are also vital. To grasp enemy's communication machine parameters will contribute to our jamming and electron counter mission efficiently. There is also great benefit of military intelligence collection if we could recover the messages or audio of the transmitted signal. However, most of the published researches just focus on the applications and the inherent merits of the FH communications. The studies of counter measures and related techniques for FH communications are rare in the literature.
In this thesis, we probe into counter viewpoint to operate the time-frequency analysis of FH signal under the unclear synchronous scheme by applying the Short-Time Fourier Transform (STFT) and design a frequency hopping demodulation scheme to intercept, estimate and demodulate the signal of Slow Frequency Hopping (SFH) M-ary Frequency Shift Keying (MFSK) and Frequency Modulation (FM).
By the simulation validation, the proposed FH interceptor architecture can correctly estimate the important parameters such as FH signal frequency, hopping duration, symbol duration and the alphabet size of M-ary symbol. This architecture concept is valuable to realize the workable off-line or on-line interceptor.

1. 緒論 1
1.1 研究動機與目的 1
1.2 論文架構 3
2. 跳頻展頻通信系統 5
2.1 跳頻展頻通信系統架構 6
2.1.1 跳頻展頻傳送機 7
2.1.2 跳頻展頻接收機 12
2.1.3 MFSK信號解調與偵測 13
2.2 假雜訊碼序列 16
2.2.1 假雜訊碼序列產生器 16
2.2.2 最大長度序列 17
2.2.3 最大長度序列之隨機特性 18
3. 跳頻信號相關參數之估測 21
3.1 時頻域信號分析 21
3.2 短時傅立葉轉換法 22
3.2.1 短時傅立葉轉換法數學模型 22
3.2.2 窗型函數效應 24
3.3 跳頻參數之估測 25
4. 模擬架構與性能分析 28
4.1 模擬架構 28
4.1.1 發射機架構 28
4.1.2 截接收機架構 28
4.2 模擬結果與性能分析 31
4.2.1 跳頻通道檢測 31
4.2.2 信號解調 37
4.2.3 跳頻頻段分析 42
5. 討論與建議 44
參考文獻 45

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