Parking sensor systems use ultrasonic proximity detectors embedded in the front and/or rear bumpers, to measure the distances to nearby objects at low level. The sensors measure the time taken for each sound pulse to be reflected back to the receiver.Depending on the speed of the vehicle and the distance to the obstacle, the system will warn the driver by visual and/or audible means about the risk of collision. The feedback to the driver will generally indicate the direction and proximity of the obstacle. Warnings are deactivated when the vehicle exceeds a certain speed, and can be switched off for situations such as stop-and-go traffic.
Radiology is medical specialty that employs the use of imaging to both diagnose and treat disease visualized within the human body. Radiologists utilize an array of imaging technologies (such as x-ray radiography, ultrasound, computed tomography (CT), nuclear medicine, positron emission tomography (PET) and magnetic resonance imaging (MRI)) to diagnose or treat diseases. Interventional radiology is the performance of (usually minimally invasive) medical procedures with the guidance of imaging technologies. The acquisition of medical imaging is usually carried out by the radiographer or radiologic technologist.
Sonar stands for SOund NAvigation Ranging. Sonar is used in navigation, forecasting weather, and for tracking aircraft, ships, submarines, and missiles. Sonar devices work by bouncing sound waves off objects to determine their location. A sonar unit consists of an ultrasonic transmitter and a receiver. On boats, the receiver is mounted on the bottom of the ship. To measure water depth, for instance, the transmitter sends out a short pulse of sound, and later, the receiver picks up the reflected sound. The water depth is determined from the time elapsed between the emission of the ultrasonic sound and the reception of its reflection off the sea-floor. In the diagram below, a ship sends out ultrasonic waves (green) in order to detect schools of fish swimming beneath. The waves reflect off the fish (white), and return to the ship where they are detected and the depth of the fish is determined.
Radar is an object-detection system which uses electromagnetic waves— specifically radio waves — to determine the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish, or antenna, transmits pulses of radio waves or microwaves which bounce off any object in their path. The object returns a tiny part of the wave's energy to a dish or antenna which is usually located at the same site as the transmitter.