Practical Estimation of the Maturity of Water Melon

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This research has carried about five years in our labaratory under the standpoint that the optimum harvesting time depends upon the matyrity of water melon. Two kinds of mearsing apparatus for estimating the optimum harvesting time are developed.1 Filter method : This appratus is composed with microphon ,notch filter to make the frequency and LED level meter to indicate the sound signal. When the frequency of the sound agrees with the frequency of the notch filter, the output level between just after filter and just before filter is pallel with maturity of the water melon. Previous research have dissolved the relation between the frequency and maturity of the water melon.2 Computer aided method : From the frequency data of the hitting sounds and delivered accerelation through the water melon and the physical data of the water melon, the maturity of the water melon is estimated. This proccesor is composed to microphon and its amplyfier to catch the hitting sound of the water melon,A-D comvertor to make sound data to digital data,16-bit one board computer system that analyses the data,calculates the power spectral density and calculates and estimates the maturity, is carried and LED idicator system indicates the estimating results. After the data of sound being A-D converted,the data is analysed to get the values of attack time,sustain time, release time and symmetry of the frequency. The power spectral density is calculated from the method of FFT and then evaluated and estimated the maturity of the water melon.