The Design And Implementation Of A Real-time Ndvi Measuring Instrument

The use of chemical fertilizer increased year by year in our country. Theincrease of fertilizer use and low use efficiency not only caused huge economiclosses, but also caused severe environmental pollution. In order to control thefertilizing amount and realize precision variable rate fertilizing, so take theNormalized Difference Vegetation Index (NDVI) measuring method as basis inguiding variable rate fertilizing.But, in our country the link to measure NDVI value mainly rely on foreignimport instrumentation with high cost, largely limits its application. And thedomestic research on NDVI value measurement mainly direct at passive lightsource is vulnerable to air and crop environmental impact. Therefore, this paperresearches the NDVI measuring system with adopting active light source. Thesystem can be good to minimize measurement error caused by the sun inmeasurement process, so as to realize accurate measurement in NDVI value andthe crop NDVI value in different growth can be got through measurement.The agriculture status of development is analyzed, the importance ofvariable rate fertilizing is discussed, and the current situation of precisionfertilization at home and abroad is introduced. Contraposing the relationshipbetween remote sensing technology and crop condition, the theoretical basis ofdetermining fertilizing amount based on NDVI value is presented. Besides, thefertilizing amount is set by the aid of NDVI value and variable rate fertilizingalgorithm based on spectral index, and the method of variable rate fertilizing bymanual set is introduced. The software and hardware design of NDVIadmeasuring apparatus is introduced. The hardware design includes opticalsystem design and control design, and the software design adopts modular andstructured programming. This paper introduced the function and design of eachmodule.The instrument is in low cost, simply operated, and its error is relativelysmall. The crop NDVI value in different growth can be got through system whichcan determine the fertilizing amount. Thus the use of chemical fertilizers can be controlled and the economic losses and environmental pollution caused byoverfertilization can be reduced.