A New Method of Sound Travel-Time Measurement in Stored Grain

The measurement of sound travel-time in grain bulk was researched for monitoring grain temperature by the acoustic method. A measurement system of sound travel-time in stored grain based on the virtual instrument was built. A time-delay estimation method using triple correlation with wavelet transform is proposed for solving the problem of sound attenuation in grain bulk. Sound travel-time in soybeans was measured by the proposed method, cross-correlation method, and cross-correlation with wavelet transform method. The results show that the proposed method is best in measurement stability and accuracy. Thus it is expected to be used in an actual acoustic temperature monitoring system for stored grain.