Ultrasonic Distance Sensor

Ultrasonic Distance Sensor

What is an Ultrasonic Distance Sensor?

An ultrasonic distance sensor is a device that is used to measure the distance to an object, the speed or size of that object by using ultrasonic sound waves.

Principle of work

The principle of work of the ultrasonic distance sensor is "Doppler Effect"


What is Doppler Effect

When a sound with a specific frequency is sent by a transmitter, if it hits a wall or any other barrier, it will reflect and return. The returned sound has always a different frequency than that of the sound sent.


The structure of ultrasonic distance sensors (In General)

Ultrasonic distance sensors are composed of two circuits: the transmitter and receiver circuits.

  1. The transmitter circuit is fed by a square generator oscillator.
  2. The receiver circuit consists of an op amp (IC 741) used as a comparator.


Active materials of the transmitter and the receiver in ultrasonic distance sensor

The active materials of the transmitter and receiver in the ultrasonic distance sensor are piezzo electric components.


Types of ultrasonic distance sensors (in terms of the transmitter & receiver)

  1. Polaroid type (the transmitter and the receiver are together)
  2. Hi-technic type (the transmitter and the receiver are separated)


Areas of use for ultrasonic distance sensors

Ultrasonic distance sensors are used for measuring the distance, speed, and size of an object located far from the sensor. Therefore; They are used in a wide range of applications. However; the most common areas of use for ultrasonic distance sensors are:

  1. Building and car alarm systems.
  2. Car parking control systems.
  3. Level measures of liquids in liquid tanks.
  4. Automatic doors' control systems.

Technical issues

  1. The electrical output of the ultrasonic distance sensor depends on the distance of the material to the sensor and on the physical size of that material.
  2. The detection distances of ultrasonic distance sensors are very long.

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