Acoustic Detection Of Watermelon Based On Wavelet Transform

Commonly known and loved as crispy, juicy, sweet and nutritious, watermelon is widely cultivated around the globe. Farmers and ordinary consumers are very concerned about picking and marketing opportunities of watermelon, and ripe choosing. Traditionally, watermelon maturity is judged by manual identification and practical experience, such as looking, touching, clapping and weighing in the hands. However, this method was largely influenced by subjective factors of inspectors, and it can hardly be widely used in large-scale production. In order to pursue an efficient, accurate and nondestructive detection that can be applied to watermelon picking and sales sections, people have been exploring it for thousands of years. With the development of modern science and technology, people have explored a variety of detection technology from the last century. Acoustic and vibratory characteristics of the lossless measurement method has attracted much attention of researchers because of its advantages, such as simple equipments, low cost, easy accessibility, and less interference by environment.Combined with the application situation of acoustic lossless measurement technique in the field of watermelon detection home and abroad, this paper discusses the realization of watermelon maturity measurement method on the basis of wavelet transformation. A theoretical model of watermelon medium acoustic wave propagation velocity and elastic properties is initially established to experiment and determine the acoustic velocity, and to estimate the elastic modulus of watermelon medium. In the meanwhile, the acquired on acoustic signal is analyzed by the wavelet transformation to extract the time-frequency feature of acoustic transmission, to study the relationship between the transmission frequency and maturity of different watermelon internal structure, especially the correlation of acoustic wave propagation frequency and sugar content. This research examines the association rules between the frequency characteristics of acoustic wave transmission and maturity of watermelon, and explores the time-frequency characteristic inversion of acoustic signal of sugar content, to estimate technical mothod of maturity of watermelon. Both theoretical analysis and experimental results indicate that wavelet transformation is one of the effective detection methods in watermelon maturity acoustic detection. It provides a strong theoretical foundation for relative detective instruments’ development.