以LoRa無線通訊技術建立供水水質即時監測系統

Abstract

馬祖南竿島以海水淡化水混合淨水場出水供應自來水，自來水供水水質受淡水與海水淡化水混合比例影響甚鉅，若海水淡化廠設備操作不當或因故損壞導致水質出現異常，導電度將會大幅上升，目前並無即時監測系統可通知此狀況。另加上淨水場餘氯監測系統目前採用之無線通訊系統為通用封包無線服務（General Packet Radio Service, GPRS），此服務使用的行動電話業務頻譜由國家通訊傳播委員會公告將於106年6月30日終止，屆時將會影響監測系統正常運作。為了改善上述狀況，本研究以LoRa無線通訊技術建立供水水質即時監測系統，並將此系統設置於淨水場之出水檢驗口。 本研究設置之系統可分為感測器、上傳器、無線通訊模組、伺服器等部分。由於導電度感測電極產生之訊號無法直接由LoRa無線通訊模組發送，因此使用開發板編寫程式將感測電極、開發板及無線通訊模組整合為感測器，並將感測電極讀取之訊號經轉換後以無線通訊模組發送至上傳器。由開發板與無線通訊模組整合之上傳器將接收到的數據經程式分類為日期、時間、測值等項目後將資料上傳至伺服器，伺服器將資料儲存至資料庫並產生數據顯示介面。水質即時監測系統設置於連江縣南竿島儲水沃淨水場，進行系統測試及評估系統穩定性與可行性。 LoRa無線通訊模組經室內訊號傳送穩定性測試其數據傳送遺失率低於5%，而實場測試結果為系統數據傳送遺失率每日均低於5%。結果顯示LoRa無線通訊技術可應用於建立水質即時監測系統，往後可與其他水質測項之感測器與本研究之系統進行軟硬體整合。

Water supply system in Nankan is a mix of purified water and desalinated water. The quality of tap water is affected by the mixing ratio of purified water and desalinated water. When the equipment of the desalination plant is improperly operated or failed, the conductivity of tap water often increases sharply. However, there is no real-time water quality monitoring system to alarm in water supply system. In addition, there have other problem is that the wireless communication system at water purification plant is General Packet Radio Service (GPRS), and National Communication Committee announced 2G spectrum to be withdrawn in June 30, 2017. They affect the operation of the monitoring system. This study aimed to use the Long-Range wireless communication system to establish a real-time water quality monitoring system in outlying islands. The real-time water quality monitoring system was divided into four parts, including sensor, uploader, wireless communication modules, and server. Because the signal generated by the conductivity probe could not be transmitted by Long-Range wireless communication module, the signal was converted by the evaluation board to the data format, which could be transmitted to uploader. The data that was integrated by the evaluation board and Long-Range wireless communication module was classified by program into data, time, and value. The server saved the data to the database and generated display interface. The real-time water quality monitoring system was set in water purification plant in Nangan Township, Lianjiang County, and the stability and feasibility of the system are tested and evaluated. In the indoor signal transmission stability testing, data transmission loss rate of Long-Range wireless communication module was less than 5%, and data transmission loss rate of the real-time water quality monitoring system was less than 5%. The result has shown that Long-Range wireless communication module is feasible to the real-time water quality monitoring practice, and available to combine other water quality sensor probe in the system.