Application of Spectrum-Subtracted Sub-band Singular Spectrum Entro- py in Sediment Thickness Measurement

Obtaining the wave head location and acoustic time difference with high accuracy in measuring sediment thickness in borehole by ultrasonic is a key and hard problem. The methods available now can’t meet the precision and noise immunity requirement. This paper utilizes the good performance of Spectrum-Subtracted sub-Band Singular Spectrum Entropy (SSB-SSE) to process the echoes reflected from the sediment and get their wave head positions. Based on these obtained data, acoustic time difference can be calculated, then the sediment thickness can be achieved. The results of three typical experiments show that SSB-SSE is very suitable in locating the wave heads of thicker sediment layer’s echoes, and it also performs well even when the echo is covered by noise.