The document explains the working principles of an ultrasonic sensor, which measures distance to objects using ultrasonic sound waves. It details the physics behind ultrasonic waves, including their frequency range and the steps involved in transmitting, reflecting, receiving, and calculating distances based on the time taken for the waves to return. Additional information on the sensor's pre-processing requirements and how to implement it with a microcontroller is also provided.

1. FORMATIVE ASSESSMENT 1
SUBJECT- MDM: EMBEDDED SYSTEM DESIGN-
SENSORS AND TRANSDUCERS
ULTRASONIC SENSOR
PRESENTED BY
AKASH ABHIMAN SAWANT
PRN NO. 124B2G030

2. ULTRASONIC SENSOR
An ultrasonic sensor is an instrument that measures the distance to an object using
ultrasonic sound waves.
• An ultrasonic sensor uses a transducer to send and receive ultrasonic pulses that
relay back information about an object’s proximity.

3. LAWS OF PHYSICS OF ULTRASONIC WAVES
• Sound waves are having specific frequencies or number of oscillations per
second. Humans can detect sounds in a frequency range from about 20Hz to
20 KHz. However the frequency range normally employed in ultrasonic
detection is 100 KHz to 50MHz.
• The velocity of ultrasound at a particular time and temperature is constant in
a medium

4. WORKING OF ULTRASONIC SENSOR
• Transmission of Ultrasonic Waves: The transmitter emits a high-frequency sound wave
(typically above 20 kHz, which is inaudible to humans) in a particular direction.
• Reflection of Waves: When the wave hits an object, it reflects back to the sensor.
• Reception of Reflected Wave: The receiver detects this reflected wave.

5. • Time Calculation: The sensor measures the time taken for the transmitted wave to hit the
object and return to the receiver.
• Distance Measurement: Using the speed of sound in the air (approximately 343 meters per
second), the sensor calculates the distance using the formula:
Distance =Speed of Sound × Time / 2
Where,
Time = Echo pulse duration.
Speed of Sound = 343 m/s (at 20°C)

6. PRE-PROCESSING OF THE ULTRASONIC SENSOR
• Power the Sensor using a regulated +5V through the Vcc ad Ground pins of the
sensor
• The Trigger and the Echo pins are both I/O pins and hence they can be
connected to I/O pins of the microcontroller.
• To start the measurement, the trigger pin has to be made high for 10uS and then
turned off. This action will trigger an ultrasonic wave at frequency of 40Hz
from the transmitter and the receiver will wait for the wave to return

7. Once the wave is returned after it getting reflected by any object the Echo pin goes
high for a particular amount of time which will be equal to the time taken for the wave
to return back to the sensor.
• The amount of time during which the Echo pin stays high is measured by the
MCU/MPU as it gives the information about the time taken for the wave to return
back to the Sensor. Using this information the distance is measured as explained in
the above head

8. FINAL CIRCUIT

9. SIMPLE EX. WATER LEVEL MAINTAIN

10. THANK YOU