Ultrasonic range finding

Ultrasonic range finding

A common use of ultrasound is in range finding; this use is also called sonar. This works simiarly to radar: An ultrasonic pulse is generated in a particular direction. If there is an object in the path of this pulse, part or all of the pulse will be reflected back to the sender as an echo and can be detected. By measuring the difference in time between the pulse being transmitted and the echo being received, it is possible to determine how far away the object is.Although range finding underwater is performed at both sub-audible and audible frequencies for great distances (1000 to 30000 meters), ultrasonic range finding is used when distances are shorter and the accuracy of the distance measurement is desired to be finer. Ultrasonic measurements may be limited from about a hundred to a thousand meters, but be performed with one-centimeter to one-meter accuracy.Bats use a variety of ultrasonic ranging (echolocation) techniques to detect their prey.

Ability to hear ultrasound

Backup Sensors use Ultrasonic (Ultrasound) technology.

Ability to hear ultrasound

Some animals, such as dogs, dolphins, bats, and mice have an upper frequency limit that is greater than that of the human ear and thus can hear ultrasound. Children can hear some high-pitched sounds that older adults cannot hear, as in humans the upper limit pitch of hearing gets lower with age (a cell phone company has used this to create ring signals only able to be heard by younger humans[1]). This frequency limit is caused by the middle ear that acts as a low-pas filter. If ultrasound is fed directly into the skull bone and reaches the cochlea without passing through the middle ear, much higher frequencies (up to about 200 kHz) can be heard. This effect (sometimes called ultrasonic hearing) was first discovered by divers exposed to a high-frequency (ca. 50 kHz) sonar signal.

Reverse backup sensors

Reverse backup sensors (also known as reverse parking sensors, reverse parking systems, and reverse backing systems) are a technology that allows the driver of a car, truck, van or commercial vehicle to be alerted to nearby objects in their path.
While there are variants in the design and feaures of these systems the basic design puts sensors in the car bumper or on brackets. These sensors send ultrasonic waves (4 times/second) that detect obstacles behind the vehicle. A controller installed inside the vehicle then receives the signal from the sensors and transmits it to a speaker that emits a tone, or to a combination speaker and display unit.

Consumers in trucks drive demand for backup sensors

Consumers in trucks drive demand for backup sensors
By David Kiley USA TODAY

DETROIT — Consumers, many now driving trucks with big blind spots that block the view behind them, are rushing the market for alarms that warn when they are backing close to something.

Drivers of minivans, pickups and sport-utility vehicles are backing into and killing an average 88 people a year, besides causing billions of dollars of property damage. That's out of an average 116 people a year killed — a third of them children — by any kind of vehicle backing up, says the Centers for Disease Control.

Backup alarms that beep inside a truck or car when it is backing close to something are becoming one of the hottest automotive products, either as a manufacturer's option or aftermarket addition.

Outside, the systems look like several buttons set into the bumper. Inside, they beep faster as the vehicle nears an obstruction.

Ford Motor has one of the most sophisticated systems. It uses signals from both sonar and radar sensors in the rear bumper to detect moving and stationary obstacles up to 20 feet behind the vehicle.

Ford figured 20% of buyers would take the option last year on its Lincoln Navigator full-size SUV. Instead, 80% did, so Ford made it standard on the '03 Navigator and is looking to expand the number of models that offer it.

That kind of demand has created additional problems:
Drivers who have the alarms are developing false confidence. Automakers say most of the systems are designed to prevent backing into stationary obstacles, such as posts or other cars, and can't reliably detect children, pets or other moving objects. For more information visit http://www.usatoday.com/money/autos/2002-10-13-back-up-alarms_x.htm