Ultrasonic SensorsBasic knowledge about ultrasonic sensors: basic circuit configuration

Here we describe a basic circuit for distance detection using an ultrasonic sensor (Open structure type). The circuit for distance detection uses a method called pulse reflection in which the reflection time is measured from the transmission of an ultrasonic wave pulse to the reception of the pulse. The relationship between the distance to the object (L) and the reflection time (T) is expressed by the following equation:

L = C × 1/2 × T. Here, C represents the speed of sound. After measuring the time of flight (TOF),

that is to say the reflection time to the object, it is possible to calculate the distance to the object.
In the figure below the basic circuit configuration is shown as reference information.

Here we describe ICs from Texas Instruments for operating ultrasonic sensors (Open structure type), such as their ultrasonic sensing AFE products.
This information can be put to good use both in evaluation and in the design of the actual operation circuit.

• The ultrasonic IC webpage of Texas Instruments is here.

Software that utilizes a variety of sensor signals is essential to many IoT applications. In an increasing number of cases, programming tools such as those featured below are used to create software for the operations that take place following reception of ultrasonic wave signals (for example, software that sounds an alarm when a person approaches to within a distance of X meters).