According to: Technique Regulation of Concrete Defect Detection with Ultrasonic CECS21: 2000 Depth measurement principle When vibration energy transmits through the concrete and passes the crack, the vibrate energy will be diffracted at the point of the crack, whose diffraction angle has geometrical relationship with the crack depth. DJCS-05 crack depth measurement instrument adopts this geometrical between the diffraction angle and depth to realize high precision depth measurement. Feature and Specification Easily operation: Start measure when turn on, simply press to finish testing. Result Intuition: No wave speed test and calculate to display the crack depth directly Data processing: Data can transfer to PC, and then generate test report rapidly. Depth scale: 10-350mm Test precision: 5% Data storage: 10600 depth data Display: 4” Resolution 160*128 Power supply: 9VDC (6 AA battery) Work environment: Temperature -5~40centigrade; Humidity 85% Size: 220*180*80mm Weight: 1000g