橋梁振動頻率為橋梁安全之重要依據之一，本研究透過高精 度速度儀來量測橋梁自然振動頻率，同時研發接收器來接收速度規 之量測數據，再透過多點跳躍之無線感測網路，將資料回傳至以中 繼站，再以嵌入式系統進行資料儲存，經過實驗室之壓力測試成功 後，資料遺失率小於0.6%，顯示訊號接收效果佳；使用電力方面， 若採用12 伏特電池來計算一天設備之耗電量，前端站約為3 安培小 時(AH)電池，中繼站約為30 安培小時(AH)，本系統未來將透過自然 頻率之變化，來監測於洪水期間橋墩沖刷深度。

The vibration frequency of bridge is the one of important basis for bridge safety. This study adopted the high precision speed meter to measure the nature frequency of bridge, which is received by a self-developed receiver. The multi-hop function of wireless sensor network will be applied to transmit the data into the mid-station. A embedded system saved the data. After the pressure test in the laboratory, the loss rate of data is small than 0.6%, which shows a good receiving rate. If the 12 voltage battery is used, the consuming power of one day is 3 ampere hour in the front station and 30 ampere hour in the mid-station. This system will be applied to estimate the erosion depth of bridge pier by the variation of nature frequency during the flood period.