Practical Estimation of the Maturity of Water Melon

本研究在实验室进行了近五年的研究，认为西瓜的最佳采收期取决于西瓜的成熟度。研制了两种估测最佳收割时间的测定仪：1滤波法：该测定仪由传声器、陷波测频和LED液位计组成。当声音的频率与陷波滤器的频率一致时，恰好在滤波器之后和恰好在滤波器之前的输出电平与西瓜的成熟度是平行的。前人的研究已经解决了西瓜成熟度与频率之间的关系。2.计算机辅助方法：根据西瓜击打声的频率数据和西瓜的物理数据，判断西瓜的成熟度。该处理器由用于捕捉西瓜击打声的麦克风及其放大器、用于将声音数据转换为数字数据的A-D转换器、用于对数据进行分析、计算功率谱密度和计算成熟度的16位单板机系统组成，并由LED模拟器系统显示估计结果。声音数据经过A-D转换后，对数据进行分析，得到攻击时间、持续时间、释放时间和频率对称性的值。利用快速傅立叶变换的方法计算出西瓜的功率谱密度，进而对西瓜成熟度进行评价和估计。

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.