Design Of The Reflective Near Infraded Moisture Measurement Instrument Based On The Method Of Three Wave Bands And Six Beams

Reflective near infraded moisture measurement instrument is an important application of near infraded spectrum. When near infraded beam is irradiated to the tested material, the attenuation of the reflection of beam can reflect the moisture content. The measurement method based on three wave bands and six beams can elimate the measurement error caused by the change of the lamp and the tested material.Based on the research of near infraded measurement theory, optimized design method of three wave bands and six beams is proposed in the paper to complete the overall design of the instrument and improve the stablity. Then according to the low noise analysis and reasearch of the confidential component Pbs detector, method of low noise moisture signal measurement system is detailed designed and implemented through system hardware circuit optimized design. The precised sampling and processing of the moisture signal is implemented by designing software procedure using reasonable data processing method, which improves the precision of the instrument. PC monitoring software is designed to store and manage the moisture data.Hardware circuit system mainly include the high precision power system circuit, low noise moisure signal measurement circuit, high precision temperature control system circuit and central processing circuit.The design of software data processing method mainly include the sample ratio algorithm, sample integration and digital average filter algorithm, PID control algorithm and stable frequency interference filter algorithm.Through a lot of measurement experiments and performance tests after calibration, the designed reflective near infraded moisture measurement instrument is proved to have a good stability and repeatability. Calibration data fitting method is analyzed and compared to do the moisture content measurement experiment. The experiment result indicates that the measurement error of the instrument is small, which can satisfy the need of practical application.