在本論文中,我們提出在數位通訊系統中對傳播延遲時間估測的最大概似演算法。我們使用光纖模擬軟體OptSim來模擬光纖通訊系統並使用最大概似估計演算法來估測傳播延遲時間。在模擬的過程中,我們考慮了訊號衰減、通道色散以及可加白色高斯雜訊的影響。我們將128個二位元資料串以不同資料傳輸速率透過單模光纖傳輸在接收端對傳播延遲時間作估測。研究結果顯示我們提出的最大概似估計演算法在高低資料傳輸速率皆有準確的估測。而此演算法在通道色散影響下也有好的效能。 In this thesis, we present a maximum-likelihood (ML) algorithm for estimating propagation delays in digital communication systems. The ML estimate algorithm is then tested on an optical fiber communication system using the OptSim software package. The effects of signal attenuation, channel dispersion and the additive white Gaussian noise are considered in our simulations. We transmit 128 bit binary data sequences over a single mode fiber at various transmission rates and estimate the propagation delay at the receiver. Study results show that our ML estimation algorithm yields accurate estimates for both low and high data rates. The algorithm also works very well under channel dispersion.