小型生物雷達定位系統之模擬與實現

本篇論文主要探討如何結合被動射頻標籤(passive RFID)與無線定位技術，發展成小型生物定位及識別雷達系統，目的在於定位與辨識出多個帶有標籤的小型生物，例如紅火蟻。本系統使用到達角度定位法(Angle of Arrival, AOA)無線定位技術，並且假設為遠場的情況下，以分時多組的方式進行，也就是一個單位時間內只喚醒一個標籤做定位。由讀取端發送訊號至標籤端喚醒一個標籤後，此標籤將反射訊號做角度估測，其餘多個沒有喚醒的標籤理論上為關閉狀態不反射訊號，藉此可以有效地避開多個不同的標籤間訊號干擾，但是實際上標籤電路關閉的狀態下還是會有部分訊號洩漏出來，並且造成干擾，同時也存在著一些環境因素導致訊號不理想的問題。本篇論文主要針對實測時傳送天線造成的干擾問題，提出了非同步消除干擾演算法，也提出在二維平面使用的位置估測演算法。模擬結果顯示位置之估測結果會隨著位置估測演算法的迭代次數增加而更加準確，且高輸出訊雜比(SNR)情況下會接近理想狀態，而非同步消除干擾演算法也可從模擬結果得知可減少干擾量造成的估測位置距離誤差，且高輸出訊雜比(SNR)情況下會趨於穩定狀態。在模擬結果中也會提供以實測所得到之角度資料所做的位置分布圖。

關鍵字

被動射頻標籤；無線定位技術；抵達角度定位法

並列摘要

The aim of this thesis is to develop positioning and identification algorithms for a 3-dimensional high-resolution radar system. This radar system will be employed for positioning and identification of some small-sized creatures, such as red fire ants. Therefore, the developing radar system not only performs identification like a radio frequency identification (RFID) system but also performs positioning like a conventional radar system. In order to easily mount tags on small-sized creatures, a feasible solution is to used passive RFID technologies and employ some sophisticated algorithms on the reader side for positioning and identification. We use time division multiple access method to locate tags. At any instance, only a tag is awakened to active mode for positioning and the other tags are at sleep mode. After awaking the target tag by sending an ID code, the target tag will reflect signals that allows the reader to estimate the angle of arrival of the reflected signal. In this way, we can efficiently avoid the interference of different tags. However, the tags staying at sleep mode would leak some signal and cause interference because of the circuit imperfection. This thesis proposes an asynchronous cancellation algorithm to cancel the interference from the transmission antenna when measuring, and also proposes a positioning algorithm that can be used in the two-dimensional coordinate plane. The simulations show that increasing the number of iterations of the positioning algorithm will improve the accuracy and the performance is very close to that of the interference-free case at high output signal-to-noise ratio(SNR). The simulations also display that positioning error becomes smaller after cancellation and is stable at high output signal-to-noise ratio(SNR).

並列關鍵字

passive RFID ； wireless positioning technology ； Angle of Arrival

參考文獻

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國際替代計量

小型生物雷達定位系統之模擬與實現

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