【作者】 潘佚；

【导师】 郑筱祥； 叶树明；

【作者基本信息】 浙江大学 ， 生物医学工程， 2011， 博士

【摘要】 海洋叶绿素原位监测对海洋科学研究和环境监测有重要意义。水体叶绿素含量随时间和空间变化,传统实验室测量方法难以反映有机物质在生态系统中的真实情况,原位测量成为发展方向。海水叶绿素浓度含量低,测量环境复杂(阳光干扰、照明干扰等)、原位测量时间持续长等工作条件要求原位仪器必须满足高精度、强抗干扰和低功耗等关键技术需求。传统非原位测量在实验室中进行,可通过屏蔽、暗室环境来避免干扰；传统原位测量仪器则使用基于LED的脉冲调制方案来提高抗噪声和抗干扰性能。在功耗、体积的限制下,现有设计方案已无法在测量精度、抗噪声和干扰性能方面再有显著提高。针对这种情况,论文结合伪随机信号处理技术、光调制技术和近年国内外水下原位荧光仪器的研究成果,创新性地从调制方法入手,利用伪随机序列的相关特性和频谱扩展效应,提出了一种适用于原位荧光测量系统的、基于伪随机序列的荧光调制方案,并应用于高信噪／干比、高精度、低功耗的原位荧光测量仪器。本论文的主要工作内容和创新点为：1、建立了荧光测量系统信号传输的数学模型,从信号、噪声和干扰的频谱角度定量分析了伪随机序列调制系统对噪声和干扰的抑制能力,通过数学分析和仿真等手段给出了序列参数与测量系统的抗噪声、抗干扰性能之间的定量关系；2、根据伪随机序列调制原理设计了一套原位荧光检测系统的设计方案,该方案由基于LED和光电二极管的光电检测模块、信号处理、调制、同步解调模块、采样和通信模块组成,可以很好地实现原位叶绿素的伪随机调制检测；3、研制了伪随机序列调制的叶绿素荧光原位检测系统样机,对调制码宽和调制序列等关键参数进行了评估与优化,提高了信噪比和信干比特性,特别是在窄带系统中调制序列的优化设计；4、对基于伪随机序列调制的叶绿素荧光原位检测样机进行了测试。叶绿素口的测量精度达到0.02μg/L,测量范围0～150μg/L,达到国外同类高端仪器水平；抗干扰能力则优于同类仪器,在干扰频率与调制频率相近情况下,输出信干比比传统调制方式提升30dB以上。本论文研制的基于伪随机序列调制的原位叶绿素荧光检测系统与传统仪器相比,在同等硬件、功耗和检测精度条件下,大大提升了仪器抗干扰能力,具有很好的实用前景。更多还原

【Abstract】 In-situ chlorophyll fluorescence detecting instrument has been widely used in the marine scientific research, environmental monitoring, and other fields. However, the market of similar high-end devices has been occupied by imported products for a long time. The most important function of in-situ fluorescence instrument is to detect weak fluorescence signal in nature environment. It is difficult to significantly improve the measuring accuracy by using existing design scheme due to the complex background noise and interference produced in measurement process, as well as the limitation of the volume and power of devices. Aiming at this situation and starting with modulation theory, this dissertation puts forward a new exciting light modulation method to improve instrument performance.Pseudo-random signal processing theory has also been widely applied in project fields. Combining the pseudo-random signal, optical modulation technology and the achievements of submersible organic matter in-situ measurement researches in recent years, this dissertation proposed an exciting light modulation method for fluorescence measurement system by using pseudo-random sequences, based on its correlation and spread-spectrum characteristic.The main tasks and results of this dissertation are summarized as following:1. Starting from the characteristics of in situ fluorescence measurements instrument, the necessity and methods of improving measurement accuracy were discussed, and the effect of excitation light modulation on fluorescence system was analyzed.2. Through establishing mathematical model, the quantitative analysis of noise and interference performance in this system has been given in this dissertation, as well as the relationship between sequence parameters and the system SNR.3. The simulation was carried out with Matlab/simulink to to verify the correctness of theoretical analysis. Comparing with the square-wave modulation system, the result indicated that the new modulation method was feasible.4. The hardware design of in-situ fluorescence detection system, including optical and electronic modules was given. The pseudo-random sequence modulation scheme was applied in fluorescence in-situ detection prototype. By using different modulation baseband and modulation sequence, an overall assessment to the system performance parameters was carried out, especially the improvement of signal to noise/interference ratio. The optimization selection of modulation sequence in narrow-band system was emphatically discussed.Experiment data showed that the in-situ fluorescence detection system based on pseudo-random sequence modulation, which was developed in this dissertation, can significantly improve the signal to noise/interference ratio, especially for the narrow-band interference inhibiting ability, which is much better than the system that used normal modulation. The accuracy and power consumption of measurement system is up to the highest level of similar products at home and abroad. The pseudo-random sequence modulation mode has wide practical prospects in various fluorescence analysis systems.更多还原