The document discusses ultrasonic sensors. It explains that ultrasonic sensors transmit ultrasonic waves and measure the time it takes for the waves to reflect back from an object to calculate the distance. Ultrasonic sensors have a transmitter that uses piezoelectric crystals to emit sound waves and a receiver to detect the reflected waves. The distance is calculated using the speed of sound and the round trip time of the waves. Ultrasonic sensors are used for applications like distance measurement, liquid level detection, and medical imaging due to their insensitivity to factors like smoke or color.

1. Ultrasonic sensor
Priyanka jakhar
Physics (lecturer )
ATAL LAB Incharge

3. Ultrasonic sensor ---- is also known as SONAR. It is used for
measuring the distance between the object and the sensor itself. It
transmits ultrasonic waves and receives it back after reflecting from
the surface of an object.
Then its measures the time during entire process which is equal to the
distance between object and the sensor itself.
It has four pins and is very easy to use.
Ultrasonic waves travel faster than the speed of audible sound (i.e. the
sound that humans can hear).
Ultrasonic sensors have two main components:
The transmitter-- (which emits the sound using piezoelectric crystals) .
The receiver-- (which encounters the sound after it has travelled to
and from the target).
•Ultrasonic sensor transmits sound waves.
•These waves are reflected back from the surface of an object.

4. • Then it measures the time elapsed during the entire process, from
transmission to receiving, it is known as round trip time.
• This time is equal to the distance between an object and the sensor
itself.
Theoretically, the distance can be calculated using the TRD (time/rate/distance)
measurement formula.
Since the calculated distance is the distance traveled from the ultrasonic transducer to the
object—and back to the transducer—it is a two-way trip.
By dividing this distance by 2, you can determine the actual distance from the transducer to
the object.
Ultrasonic waves travel at the speed of sound (343 m/s at 20°C).
The distance between the object and the sensor is half of the distance traveled by the
sound wave.
The following equation calculates the distance to an object placed in front of an ultrasonic
sensor:
distance =
time taken x speed of sound
2

6. level sensors to detect, monitor, and regulate liquid levels in closed
containers (such as vats in chemical factories).
Most notably, ultrasonic technology has enabled the medical industry
to produce images of internal organs, identify tumors, and ensure the
health of babies in the womb.
Ultrasonic sensors are also used in robotic obstacle detection
systems, as well as manufacturing technology.
Also known as SONAR sensor. SONAR basically stands for Sound
Navigation and Ranging. Ultrasonic is mostly used for the distance
measurements. It can also be used for measuring the depth of the
sea.
Ultrasonic sensors are superior to infrared sensors because they aren’t
affected by smoke or black materials, .
Soft materials which don’t reflect the sonar (ultrasonic) waves very well may cause
issues. It’s not a perfect system, but it’s good and reliable.

7. Ultrasonic sensor has four
pins---

8. •Ultrasonic sensor has total four pins, each pin has to perform
different task.

9. Working Principle--The ultrasonic sensor (or transducer) works on the same principles as
a radar system. An ultrasonic sensor can convert electrical energy into acoustic waves and
vice versa.
The acoustic wave signal is an ultrasonic wave traveling at a frequency above 18kHz.
The famous HC SR04 ultrasonic sensor generates ultrasonic waves at 40kHz frequency.
A microcontroller is used for communication with an ultrasonic sensor. To begin measuring
the distance, the microcontroller sends a trigger signal to the ultrasonic sensor.
When triggered, the ultrasonic sensor generates eight acoustic (ultrasonic) wave bursts and
initiates a time counter. As soon as the reflected (echo) signal is received, the timer stops.
The output of the ultrasonic sensor is a high pulse with the same duration as the time
difference between transmitted ultrasonic bursts and the received echo signal.

11. Piezoelectric crystal-- a crystal, such as quartz, that produces a potential
difference across its opposite faces when under mechanical stress.
The first Piezoelectric effect was initiated in the year 1880 by the brothers Jacques
Curie & Pierre.
examples of piezoelectric crystals like quartz, tourmaline, cane sugar, Rochelle salt,
and topaz.
The main function of these materials is to exhibit piezoelectric constants several
times which are superior to normal piezoelectric materials.
The shape of piezoelectric crystal is a hexagonal, and it includes three axes namely
optical, electrical, & mechanical. It is named a piezoelectric effect.
The working of this crystal is whenever force is applied to the crystal then it
generates the electricity.
•The best application of piezoelectric crystal is an electric cigarette lighter.
•The common application of a piezoelectric-crystal energy source is to create a tiny
motor.
•The piezoelectric-crystals are embedded within the shoe sole of a shoe to generate
electricity energy for every step.
.

12. Ultrasonic sensors are also used as
Ultrasonic sensors can measure the following parameters, without even getting in contact with
the medium which is to be measured :
• Distance
• Level
• Presence
• Diameter
• Position
Ultrasonics are Independent of:
•Light
•Smoke
•Dust
•Color
•Material (except for soft surfaces, i.e. wool, because the surface absorbs the ultrasonic sound wave
and doesn’t reflect sound.)

13. Features of Ultrasonic Sensor:
•Compact and lightweight
•High sensitivity and high pressure
•High reliability
•Power consumption of 20mA
•Pulse in/out communication
•Narrow acceptance angle
•Provides exact, non-contact separation estimations within 2cm to 3m
•The explosion point LED shows estimations in the advancement
•3-pin header makes it simple to connect utilizing a servo
development link