本論文針對防丟器的剖面進行追蹤分析。防丟器包含發射器及接收器，發射器會發射訊號，接收器會記錄RSSI (Receive Signal Strength Index)與發射點數，其中RSSI表示訊號的強度。在工程理論上，RSSI與距離具有函數關係；然而環境中的干擾及事件發生都會影響此函數關係，特別是事件發生會嚴重地改變此函數關係，因此論文主要目的在於區別事件是否發生。
所謂的剖面指的是變數之間的函數關係，而論文中的剖面追蹤是利用管制圖的概念，用管制圖來監控剖面的參數估計值。如果管制圖上的點子出界，則表示事件發生而導致失控。
本論文以腳踏車是否被偷為例，嘗試一些實驗後找出顯著影響的因子設計實驗，包含17種腳踏車未被偷之情境與18種腳踏車被偷情境；欲利用未被偷的實驗建立試驗管制圖，而以被偷之情境來追蹤，用以驗證管制圖之有效性。
論文中主要透過分析防丟器產生的RSSI與距離的剖面、距離與發射點數的剖面來探討事件是否發生。另外剖面追蹤其實是種事後追蹤的方法，為了能即時追蹤，本論文亦採用預測區間的方式，來追蹤事件是否發生。
本論文建議監控距離與發射點數的剖面，因該方法的表現最好，另外建議增加防丟器上能紀錄距離的功能，此方法會更加合適。
本論文提出的即時追蹤方式並沒有特別好，因此一個比較好的即時追蹤方法是未來值得研究的方向。 / The device of Babyfinder is designed to detect if an event occurs. The Babyfinder includes transceiver and receiver. The signal strength, Received Signal Strength Indicator (RSSI), generates once there are distances between transceiver and receiver. In wireless communication theory, the relationship between RSSI and distance should be expressed by the model that RSSI = a + b ln (distance) Nevertheless, some circumstance noises and user noises (or common causes), and/or events (special causes) may affect the variation of RSSI. Since the occurrence of events may change the functional relationship of RSSI and distance, to distinguish if the functional relationship is changed by the occurred events is the subject of this study. This study designs some events and noises experiments based on the real noise factors and special events. Two monitoring schemes are proposed to distinguish the occurred events and noise circumstance. One is the profile monitoring scheme, the other is the real time monitoring scheme. The two proposed approaches of profile monitoring scheme are considered to monitor the profile of RSSI and distance and that of distance and the number of transmitting points, respectively. The profile monitoring approach for distance and the number of transmitting points shows better performance. However, the profile monitoring is an after-event tracing approach. It cannot detect the occurred events in time. A better approach of real-time monitoring approach is worth to be proposed in the future study.
| Identifer | oai:union.ndltd.org:CHENGCHI/G0097354005 |
| Creators | 徐伊萱 |
| Publisher | 國立政治大學 |
| Source Sets | National Chengchi University Libraries |
| Language | 英文 |
| Detected Language | English |
| Type | text |
| Rights | Copyright © nccu library on behalf of the copyright holders |
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