介绍了水浊度常用的测量方法-散射法、透射法及比值法的原理,在此基础上结合脉冲宽度调制(PWM)解调技术,提出了 采用调制光强测量浊度的方法,并详细介绍了实验系统的组成和调制解调实现电路。采用该实验系统对福尔马肼标 准液进行测量,列出了测量数据,并绘出三种方法所测浊度的拟合曲线。对实验结果的分析和比较表明使用PWM调制 结合比值法能最有效地排除背景光的干扰,在保证精度的前提下提高水浊度的测量范围。

The principles of three common measuring methods of the water turbidity, scattering method, transmission method and ratio method are introduced. Combined with pulse width modulation (PWM) and demodulation technique, the method for turbidity measurement using light intensity modulation is proposed and the experimental system and the realizing circuit of modulation and demodulation is described in detail. The experimental system is used to measure the turbidity of Formazine standard solution of different turbidity values. The measured data is listed, then the turbidity values fitting curve using the three methods are drawn. Through the analysis and comparison of the experimental results, it’s showed that when using the ratio method combined with the modulation technique, the interference of background light can be eliminated effectively, so the measuring range of the water turbidity can be improved with high measuring accuracy.