First, the technical indicators 1.TM material velocity: 1540 ± 10m / s (23 ± 3 ℃) 2.TM material sound attenuation coefficient slope: 0.70 ± 0.05dB / cm / MHz (23 ± 3 ℃) 3. Nylon target wire diameter : 0.3 ± 0.05mm 4. nylon target line position tolerance: ± 0.1mm Second, the detailed parameters of the axis of lateral resolution of the target group: its lateral branches, respectively, from the acoustic window 30,50,70,120 and 160mm, blind target group: relative o Target line center lateral spacing are 10mm, the distance to the sound of the window 10,9,8,7,6,5,4,3mm respectively. Longitudinal Target group: Target line containing a total of 19, the center distance between two adjacent lines are 10mm. Transverse Target group: Target line containing a total of seven, the center distance between two adjacent lines are 20mm.