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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/11126

Title: 全數位化空間濾波器之韌體設計與實現
Firmware Design and Implementation of All-Digital Spatial Filter
Authors: 洪賢昇
Contributors: NTOU:Department of Electrical Engineering
Keywords: 空間濾波器;韌體開發;帶通取樣;全數位式;盲蔽式;適應性;位置誤差;指向誤差;束波器
Spatial filter;Firmware developement;Bandpass sampling,All digital;Blind,Adaptivity;Position error;Pointing error;Beamformer
Date: 2001-08
Issue Date: 2011-06-28T08:08:27Z
Abstract: 在傳統的低通取樣理論中,訊號處理的取樣率必須高於訊號最高頻率的兩倍,因此對於具有較高載波頻率的帶通訊號,則會出現取樣率必須提高的現象。在本報告中,利用帶通取樣原理設計全數位式盲蔽適應性束波器,直接對中頻訊號進行取樣,可以有效降低類比-數位轉換器的取樣率,增加束波器在韌體上的可行性。由於束波器在實際應用中,感測器的位置經常由於人為擺設不準確,或受風及狂浪等環境因素的影響而產生誤差,以及陣列對目標信號的入射方向判斷可能發生錯誤,所以針對全數位式盲蔽適應性束波器與DS束波器、MVDR束波器,以電腦模擬方式評估在位置誤差及指向誤差下的效能。經由電腦模擬結果顯示,全數位式盲蔽適應性束波器在這些條件下能有效地抑制雜訊及干擾。最後再以實際水槽量測的資料進行電腦離線分析,驗證全數位式盲蔽適應性束波器的可行性。
In the conventional lowpass sampling theory, the sampling rate must be twice higher than the largest frequency of a low-pass signal. Therefore, the sampling rate would be largely increased for a band-pass signal with higher carrier frequency. In this report, the bandpass sampling principle is employed to design an all-digital blind adaptive beamformer, which directly takes samples from a bandpass signal, effectively reduces the sampling rate of analog-to-digital Converter, and increases the feasibility of firmware implementation. In practical applications, position errors due to hydrophone array deployment or environmental factors, such as wind and turbulent waves, as well as pointing error of the desired signal source can detrimentally affect beamformer's performance. We investigate the performances of three types of beamformers, i.e. blind, delay sum (DS), and MVDR, under position or pointing error by computer simulations. Simulation results have shown that the all-digital blind adaptive beamformer is able to effectively reduce noise and interfering signals. Finally, using the data measured in water trough by computer off-line analysis, the feasibility of the blind beamformer is verified.
Relation: NSC90-2611-E019-023
URI: http://ntour.ntou.edu.tw/ir/handle/987654321/11126
Appears in Collections:[電機工程學系] 研究計畫

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