由於電磁流量計是利用法拉第定律所產生的微小電壓來換算成流量，所以對於雜訊及外在的干擾在量測的精確度上，有著明顯的影響。本論文主旨在於如何抑制干擾源而不至於影響到流量訊號的輸出的方法，進而提高量測的精確度。文中首先探討電磁流量計技術之基本原理及其應用範疇，進而論述影響系統操作之相關因素。在激磁部份設計上，先經由比較分析抉擇適當的激磁方式，並針對此種激磁方式所產生的干擾，利用選擇激磁頻率的方式來抑制。在訊號處理電路上，經由訊號放大、濾波、取樣，使雜訊對流量訊號影響降到最低。最後經由實測驗證，本文所提電磁流量計設計方法確具可行性，使流量大小和輸出電壓成線性關係。

Because the electromagnetic flowmeter uses the Faraday’s Law to generate tiny voltage to convert into the flow rate, it has obvious influence on the noise and external interference for measurement’s accuracy. This thesis investigates the method how to suppress the interference. At first the applications and fundamental principle of the electromagnetic flowmeter is given, and followed by the discussion of the factors associated with the operating of system. In the excitatory magnetic driver, first choosing proper exciting method, then suppress the interference which is generated by this excitatory method via choosing the exciting frequency. In the signal circuit, it is processed through filtering, amplifying, and avoiding magnetic interference by sampling technology. Finally, this system obtains a voltage at output of signal circuit. It can be certified that the purpose of the output voltage proportional to the flow is achieved through the experimental results.

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