PDM (Probes Distance Meter), Distance Measuring Instrument by Using   Ultrasonic Propagation between Probes
  The innovation process is always required to produce more advanced technology and increasing productivity. PDM (Probes Distance Meter) comes as a technological innovation in measurement, PDM is a digital distance measuring instrument uses a pair of probes. PDM consists of ultrasonic transducers, a microcontroller, and screen which shows the measurement result. PDM utilizes ultrasonic wave principle by using two probes as reference points. A microcontroller is used for performing calculation that uses the distance equation. Innovation and Excellence of PDM are simple, ergonomic, modern, and able to show the measurement result automatically. PDM has additional features those are the storage media to save the measurement result with a micro-SD card, sound generation, and braille for the blinds. Those tools are expected to be suitable for common people, academics, or technicians to perform the measurement. The results from the laboratory testing show that the prototype of PDM has resolution of 1 cm, full scale of 200 cm, 11.1% repeatability, 77.6% accuracy, and a nonlinearity parameter of 0.16%. PDM is in development and it is potential to be a model of digital measuring instrument in the future that is simple, fast, and its additional features are capable to be used by the blind. 
Ridlo Qomarrullah, Abdurrachman Mappuji, Wahyu Apriliyanto, Ahmad   Harist Julianto, Farahiyah Syarafina, Iswandi
physics.ins-det physics.med-ph