... pillars.Hammer instrument: use different types of hammer (different energy/material) for different types of piles (lengths, etc.)Features: ... storage2GB,SD cardOperation ModeTouch screenTriggerSignal triggerPortsUSB portNoise voltage of the system≤2 mVDynamic range³184 dBAmplifier ... max. wave velocity, avg. wave velocity, numbers of piles of type Ⅰ,Ⅱ,Ⅲ, etc., and can generate a comprehensive excel ...