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| Application of optical modulation and demodulation technology in weed spectral identification |
| WEI Xinhua, BAO Sheng*, TAO Tao, LI Lin |
| Key Laboratory of Modern Agricultural Equipment and Technology, Ministry of Education, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract In order to identify weeds from crops rapidly and nondestructively, a spectral sensor based on spectral analysis technology was developed. In this paper, winter rape in seedling stage was served as study crop, and a prototype experimental system with the spectral sensor was designed according to four characteristic wavelengths(590, 710, 750 and 940 nm), which already had been extracted. On basis of the traditional spectral sensor, the system could eliminate the interference of the environmental stray light in detected results by using optical modulation and demodulation technology. This system included experimental equipment(optical signal modulation equipment and photoelectric signal acquisition equipment)and experimental data processing LabVIEW program. Validation experiments were performed on four different bands using winter rape leaves. When the DC component variation amplitudes, which were caused from the change in the intensity of external environmental stray light, were 10.00%, 6.40%, 1.17%, 1.34%, 22.60%, 38.90%, 56.00% and 59.50%, respectively, the reflectance always was stable. The experimental results show that the system can stably measure the reflectance of measured samples when the ambient light intensity varies either slowly or rapidly. The system confirms that the optical modulation and demodulation technology can effectively improve the signal-to-noise ratio of the measured samples.
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Received: 15 May 2017
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