A digitalized design of high-precision visibility meter transmitter

To achieve the steady output of the visibility meter probe beam, a high-precision and digitalized visibility meter transmitter based on FPGA has been designed. A bunch of scattered light has been used for the feedback signal of optical power control circuit. In FPGA, the signal entered filtering, RMS conversion, amplification and differential module to achieve current dynamic adjustment. In the temperature control unit, the increment digital PID control arithmetic has been adopted and PWM has been used for the output form. The experimental result shows that the system is stable and the fluctuation of transmitter output light intensity is 1.4%.