[Klaus] wanted some sort of aid for parking his car, and after running across a $4 ultrasonic sensor, decided to build his own speaking distance sensor (.de, Google Translation). Inside [Klaus]’ ...

Ultrasonics or ultrasound is a radar-like system that uses ultrasonic signals at frequencies above those typical for human hearing, usually above 16 to 20 kHz. The 40- to 70-kHz range tends to be most ...