Development of a wireless crop growth monitor based on optical principle

Abstract

In order to detect the plants' nitrogen content in real-time, a wireless crop growth monitor is developed. It is made up of a sensor and a controller. The sensor consists of an optical part and a circuit part. The optical part is made up of 4 optical channels and 4 photo-detectors. 2 channels receive the sunlight and the other 2 receive the reflected light from the crop canopy. The intensity of sunlight and the reflected light is measured at the wavebands of 610 nm and 1220 nm respectively. The circuit part is made up of power supply unit, 4 amplifiers and a wireless module. The controller has functions such as keyboard input, LCD display, data storage, data upload and so on. Both hardware and software are introduced in this report. Calibration tests show that the optical part has a high accuracy and the wireless transmission also has a good performance.