中文摘要：

准确获取腔衰荡信号是腔衰荡光谱技术定量探测气体浓度的基础。针对腔衰荡信号的特征，设计了一种基于FPGA的腔衰荡信号采集与处理系统。系统以FPGA为主控制器，在触发信号激励下，通过FPGA硬件逻辑实现了腔衰荡信号的高速采集、多次采样结果的对应点累加平均和USB数据传输。测试表明，系统具有较好的准确度和稳定性（准确度在4％o范围内）；实际应用于腔衰荡系统时，设计的采集系统与国外数据采集卡数据的一致性可达到99．4％。结果表明，该数据采集与处理系统可完全满足腔衰荡信号的采集要求。

英文摘要：

Accurate acquisition of cavity ring-down signal is the basis of quantitative detection of gas concen- tration by cavity ring-down spectroscopy. Aimed at the characteristics of cavity ring-down signal, a cavity ring-down signal acquisition and processing system based on FPGA is designed. FPGA is used as main con- troller of system. The system realizes high speed acquisition of the cavity ring~down signal, accumulation average of the corresponding point and transmission of the USB data under excitation of trigger signal. Tests show that the system has good accuracy and stability （accuracy in the range of 4 per thousand）. When ap- plied in cavity ring-down system, the consistency of data from the data processing system and foreign data acquisition card can reach 99.4%. Results show that the data acquisition and processing system can fully meet the acquisition requirements of cavity ring-down signal.