許多運作在窄頻電力線通道內含的設備，其內部具切換式功能的電子零件容易產生高能量的脈衝干擾訊號，常導致資料在傳輸過程中受到破壞，以致於資料失去完整性。而根據研究統計顯示，具循環穩態(cyclostationary)特性的週期性脈衝干擾為窄頻通道內最具威脅性的雜訊干擾之一，且其能量通常較背景雜訊大上數十倍以上。
為了克服脈衝干擾對資料傳輸品質的影響，以及降低傳輸錯誤率，本論文提出一循環穩態式脈衝干擾消除演算法，採用頻移濾波器(frequency shift filter, FRESH filter)來估測脈衝干擾，以改善傳統線性非時變(linear time invariant, LTI)濾波器對於循環穩態式脈衝干擾估測的效能。此外，並結合可適性雜訊預測器(adaptive noise predictor)提升重建雜訊的完整度，來降低訊號受脈衝干擾影響的程度。由模擬結果顯示，本論文所提出之演算法可有效估測及消除接收訊號中之循環穩態式脈衝干擾，相較於傳統零化法(blanking)的消除方式，其性能有顯著的提升。

There are many power devices operated in the narrowband power line channel. Therein, the electronic components with switching function will introduce high energy impulsive noise. Therefore, the data are corrupted during transmission and data integrity issue is missed. Research statistics indicate that the periodic impulsive noise with cyclostationary characteristics is one of the most threatening noises in the narrowband channel, and its energy is usually more than 10 times larger than the background noise.
In order to overcome the impact of impulsive noise on data transmission quality and to reduce the probability of transmission error, in this thesis, we propose a cyclostationary impulsive noise mitigation algorithm utilizing frequency shift (FRESH) filter to estimate impulsive noise. It can improve the performance of cyclostationary impulsive noise estimation by the conventional linear time-invariant (LTI) filter. Moreover, an adaptive noise predictor is combined to enhance the integrity of reconstructed noise, and to reduce the impact due to signal being interfered by the impulsive noise. Simulation results show that the algorithm proposed in this thesis can effectively estimate and mitigate the cyclostationary impulsive noises in the received signals and it can achieve significantly improved performance in comparison with the conventional blanking method.

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