訊號傳輸於土石流監測之功率評估

The Power Estimation of Signal Transmission in Debris Flow Monitoring

李仕煒(Shih-Wei Lee)

指導教授 ： 陸元平 ； 吳明川

國立臺北科技大學/機電學院/自動化科技研究所/碩士(2011年)

https://doi.org/10.6841/NTUT.2011.00671

摘要

近年來世界各地常有突如其來的暴雨造成土石流災害，所產生的災情是逐次嚴重，為了能準確預測土石流的發生，在土石流的防災應用中開始導入無線感測網路技術，將感測器事先埋設於可能發生土石流的區域，以便在土石流發生的初期就能監測土石流移動的資料，在災害擴大前即早進行防災的應變。而無線訊號容易受到環境的影響是眾所皆知的，尤其在土石流環境中進行無線傳輸時，除了雨水與地形植被造成的訊號干擾，最嚴重的莫過於大量的泥水侵襲，使得感測器遭受泥水覆蓋，減少訊號所能傳輸的距離，甚至訊號中斷，而無法成功傳輸土石流地區的監測資料。
為了讓無線訊號在穿透泥水時能提高資料傳輸的可靠度，目前大都以提高發射功率的方式來改善訊號衰減量，但是相對的也提高監測儀器的設計成本，因此若能了解泥水對於無線電波傳遞的衰減特性，將能在發射功率和衰減變化之間找出適合於土石流傳輸訊號的功率強度。本研究將使用防災上慣用的UHF433.9MHz頻率電波進行實驗，並加強發射功率來克服泥水所造成的能量障蔽，以找出泥水掩埋深度與功率衰減二者間的關係，提供無線感測網路在土石流監測中的環境佈建以及硬體發射功率方面能有參考依據。

關鍵字

土石流 ； 訊號衰減 ； 無線感測網路

並列摘要

In recent years, there are often sudden rainstorm causing debris flow around the world, and the effect of the disaster is becoming severer and severer. In order to accurately predict the occurrence of debris flow, researchers begin to use the technology of wireless sensor networks to precaution of debris flow. We bury the sensors into the area which may occur debris flow so that we can monitor the move data of debris flow in the initial stages of occurring debris flow and take disaster prevention before the disaster expand. The wireless signal that is easily to be affected by the environment is well known, especially in the process of wireless transmitting in the environment of debris flow. In addition to signal interference caused by rain and the vegetation, the most serious is a large number of muds attacking and results in the sensor being covered by muds. Furthermore, it reduces the distance of the signal transmitting, the signal interrupting, and fails to transmit the monitoring data of debris flow area.
In order to improve the reliability of data transmission as wireless signal penetrates the mud, nowadays, the common way is to enhance the transmission power to improve the signal attenuation, but it also increases the cost of monitoring instrument design. Therefore, if we can know the attenuation characteristics of radio waves transmission, we will be able to find an appropriate power strength of debris flow transmit signal between the transmit power and attenuation. This study will be conducted by using the usual UHF433.9MHz radio frequency to find out the relationship between the depth of buried mud and the power attenuation and offer the construction of wireless sensor networks in the environment of debris flow monitoring and the reference of hardware transmit power.

並列關鍵字

Debris flow ； Signal attenuation ； wireless sensor networks

參考文獻

[1] 尹孝元、黃清哲、連惠邦、李秉乾、周天穎、王晉倫，「自動化土石流觀測系統之發展及應用」，中華水土保持學報，第37卷，第2期，2006，第91-109頁。

[18] 黃清錦、林良宇、黃揚智、王煥文、張隆昌，近土石流發生之天候環境對2.45GHz無線信號之影響分析，電腦與通訊，2010，第71-77頁。

[30] 洪耀明、陳映熾、許祐郕、呂宏瑋、甘堯江、呂鴻廷，「地滑地即時監測系統建立之研究」，水保技術，2010，第142-150頁。

[35] 林志遠，「水中RFID技術於水產種原庫種魚監測管理之研發與應用」，農業生技產業季刊，2009，頁43-51。

[47] 陳昱仁、廖耕億、許建隆、林仲志，RFID概論：華泰文化事業股份有限公司，2009，第91頁。