由於多載波調變技術有較大的頻寬效益及較高的資料傳輸率，所以近幾年的數位傳輸系統多採用多載波調變的模式。而多載波調變信號的接收端主要是完成各個載波DQPSK信號的解調，因此在檢測解調之前必須有相位回復及時間回復的機制，以確保解調的正確性。 本論文主要針對多載波調變信號接收端的時間回復和檢測解調系統提出設計理論和運作說明，而時間回復系統方面運用數位時間回復的模式，提出時間評估系統來達到時間同步，檢測解調方面採用的是DQPSK調變信號的差分解調以及硬式決策。 本論文主要就是設計時間評估與檢測解調系統，利用SPW模擬系統的運作過程，再用Ｃ語言程式完成系統設計，將結果提出來討論，並作效能評估。 Owing to the fact that multi-tone modulation have more bandwidth efficiency and higher data rate , most digital transmission systems in the recent years adopt this kind of modulation . The major work of the receiver for the multi-tone signal is to demodulate each DQPSK signal . After demodulation , the receiver should perform phase recovery and timing recovery to assure correct of the demodulation . In this thesis , a theory concentrated on the design of the phase recovery and timing recovery system , and a description of the operation procedures . We adopt digital timing recovery methods , energy method and differential-energy method , in building timing recovery system . We adopt differential demodulation and hard decision for the demodulation and detection of the DQPSK signal . This thesis use SPW simulation tool to simulate the operation procedures and use C language to complete the design of the whole system. Finally , we discuss the various results and evaluate the efficiency .
