10-10-2017, 10:24 AM
Parking sensors are proximity sensors for road vehicles designed to alert the driver of obstacles while parking. These systems use electromagnetic or ultrasonic sensors. These systems feature ultrasonic proximity detectors to measure distances to nearby objects through sensors located on the front and / or rear bumper faces or minimized visually within adjacent grids or holes.
The sensors emit acoustic pulses, with a control unit that measures the return interval of each reflected signal and calculates the distances of the object. The system in turn alerts the driver with acoustic tones, the frequency indicates the distance of the object, with faster tones indicating a closer proximity and a continuous tone indicating a minimum predefined distance. The systems may also include visual aids, such as LED or LCD indicators to indicate the distance of the object. A vehicle may include a vehicle pictogram on the car's information and entertainment screen, with a representation of nearby objects as colored blocks.
Ultrasound is an acoustic wave with a very high frequency, beyond the human ear. Since the audible frequency range is said to be between 20Hz and 20kHz, ultrasound generally means acoustic waves above 20kHz. Bats, with their eco-location (ultrasonic biological radar), can hear sounds up to 200kHz, far beyond the capabilities of the human ear.
Ultrasound has several features that make it so useful and have led to its use in many electronics applications. First, it is inaudible to humans and therefore undetectable by the user. Second, ultrasound waves can be produced with high directivity. Third, they are a compressive vibration of matter (usually air). Finally, they have a lower propagation speed than light or radio waves.
The fact that ultrasound is inaudible to human ears is an important factor in ultrasound applications. For example, a car parking sensor system generates a sound pressure of over 100dB to ensure clear reception. This is the equivalent of the audible acoustic pressure experienced when standing close to a jet engine.
The high frequency (short wavelength) of the ultrasound allows a narrow directivity, similar to its radio wave equivalent, microwave. This feature is used in kidney stone treatments, where ultrasounds emitted from outside the body are focused on the stone to break it. Since the energy level is low, it does not damage the body.
Because ultrasound is a vibration of matter, it can also be used to examine the characteristics of that matter. Ultrasonic diagnosis uses this feature to detect and visualize the variance in reflectance and transmittance corresponding to the water content and the density of the material in the medium, for example an organ in its body.
The ultrasound travels in the air at about 340m / s like other sounds. The time it takes an ultrasound wave to travel 10 cm is about 3 ms, as opposed to 3.3 ns for light and radio waves. This allows measurement using low speed signal processing.
The sensors emit acoustic pulses, with a control unit that measures the return interval of each reflected signal and calculates the distances of the object. The system in turn alerts the driver with acoustic tones, the frequency indicates the distance of the object, with faster tones indicating a closer proximity and a continuous tone indicating a minimum predefined distance. The systems may also include visual aids, such as LED or LCD indicators to indicate the distance of the object. A vehicle may include a vehicle pictogram on the car's information and entertainment screen, with a representation of nearby objects as colored blocks.
Ultrasound is an acoustic wave with a very high frequency, beyond the human ear. Since the audible frequency range is said to be between 20Hz and 20kHz, ultrasound generally means acoustic waves above 20kHz. Bats, with their eco-location (ultrasonic biological radar), can hear sounds up to 200kHz, far beyond the capabilities of the human ear.
Ultrasound has several features that make it so useful and have led to its use in many electronics applications. First, it is inaudible to humans and therefore undetectable by the user. Second, ultrasound waves can be produced with high directivity. Third, they are a compressive vibration of matter (usually air). Finally, they have a lower propagation speed than light or radio waves.
The fact that ultrasound is inaudible to human ears is an important factor in ultrasound applications. For example, a car parking sensor system generates a sound pressure of over 100dB to ensure clear reception. This is the equivalent of the audible acoustic pressure experienced when standing close to a jet engine.
The high frequency (short wavelength) of the ultrasound allows a narrow directivity, similar to its radio wave equivalent, microwave. This feature is used in kidney stone treatments, where ultrasounds emitted from outside the body are focused on the stone to break it. Since the energy level is low, it does not damage the body.
Because ultrasound is a vibration of matter, it can also be used to examine the characteristics of that matter. Ultrasonic diagnosis uses this feature to detect and visualize the variance in reflectance and transmittance corresponding to the water content and the density of the material in the medium, for example an organ in its body.
The ultrasound travels in the air at about 340m / s like other sounds. The time it takes an ultrasound wave to travel 10 cm is about 3 ms, as opposed to 3.3 ns for light and radio waves. This allows measurement using low speed signal processing.