摘要
针对传统非调制浊度检测技术在低浊度检测中存在最低检出性能较差和精度较低的问题,提出一种基于正交相敏解调的浊度检测技术。基于浊度检测原理,分析水体中散射光的传播机理,建立了浊度与散射光强的响应特性关系;为实现微弱光电信号提取,采用一种由双通道模拟开关构成的正交相敏解调电路,详细推导正交相敏解调原理的选频鉴相特性,通过信号频谱选定和相位偏差影响修正,实现了非同频非同相噪声抑制,进而提高该系统的信噪比;研制一款浊度传感器,搭建了相应的测试装置,并对该传感器性能进行评估。实验结果表明,在0~5 NTU测量范围内,该浊度传感器具有良好的线性度、准确性和稳定性,最低检出限可达0.0049 NTU。该方法大大提高了最低检出性能和测量精度,并且从方法上避免了在低信噪比时直流漂移噪声和宽带噪声对浊度测量的影响。
To address the poor minimum detection performance and low precision of traditional non-modulated turbidity detection technology in low turbidity measurements,a turbidity detection technology based on orthogonal phase-sensitive demodulation is proposed.Based on the principle of turbidity detection,the propagation mechanism of scattered light in water is analyzed,and the response characteristic relationship between turbidity and scattered light intensity is established.To extract weak photoelectric signals,an orthogonal phase-sensitive demodulation circuit consisting of dual-channel analog switches is used.The characteristics of frequency selection and phase identification of the orthogonal phase-sensitive demodulation principle are derived in detail.By selecting the signal spectrum and correcting phase deviation influences,the suppression of noise that is neither same-frequency nor same-phase is achieved.Therefore,the signal-to-noise ratio of the system is enhanced.A turbidity sensor is developed,the corresponding test apparatus is constructed,and the performance is evaluated.Experimental results show that,within a 0~5 NTU measurement range,the turbidity sensor has good linearity,accuracy,and stability.The limit of detection can reach as low as 0.0049 NTU.This method significantly improves the minimum detection performance and measurement accuracy and methodologically avoids the impact of DC drift noise and broadband noise on turbidity measurements at low signal-to-noise ratios.
作者
阮嘉明
唐波
陈伟
Ruan Jiaming;Tang Bo;Chen Wei(College of Metrology Measurement and Instrument,China Jiliang University,Hangzhou 310018,China;Ningbo Water Meter(Group)Co.,Ltd.,Ningbo 315000,China)
出处
《仪器仪表学报》
EI
CAS
CSCD
北大核心
2023年第12期235-243,共9页
Chinese Journal of Scientific Instrument
基金
宁波市重点研发计划(2022Z092)项目资助。
关键词
浊度传感器
散射法
微弱信号检测
正交相敏解调
噪声抑制
turbidity sensor
scattering method
weak signal detection
orthogonal phase-sensitive demodulation
noise suppression
