A system and method are provided. The system includes a data reader having a processor for performing a signal frequency analysis, an ultrasound transmitter for transmitting ultrasound signals, and an ultrasound receiver for receiving reflected ultrasound signals. The system further includes a movable reflector for receiving the ultrasound signals and reflecting the ultrasounds signals back to the ultrasound receiver (a) as the reflected ultrasound signals without modulation when the movable reflector is stationary and (b) as the reflected ultrasound signals with modulation when the movable reflector is mobile. The system also includes a chip for storing a specification of motion states for the movable reflector.