This sensor uses an ultrasonic transducer to transmit an ultrasonic wave and measure the time of the echo return. In this way, the sensor measures the distance to an article located against it. Using the module software, it is able to calculate also the item velocity and acceleration. The sensor has three modes of operations: Distance, Velocity and Acceleration. Experiment Duration: 1 second to 31 days. Note: an echo can be received from bodies near the line between the motion sensor and the measured article. The size of the measured article must be at least 10 X 10 cm.