Introduction to Ultrasonic Distance Meter
The project Ultrasonic Distance Meter is a very interesting and useful project for many industrial applications. In this project we have used the ultrasonic waves to measure the distance in between two points. The basic principal is based on the speed of ultrasonic waves in open air. We have used a microcontroller AT89S51 to transmit and receive ultrasonic waves through 40 KHz ultrasonic receiver and transmitters. By measuring the time required to travel the unknown distance by ultrasonic waves in air we can find out the distance between two points. The distance measured is displayed on a LCD display. The transmission & reception of ultrasonic waves is very complex in nature so it needs very sophisticated techniques to process these waves. We have used a very complex structure of amplifier and filters for this purpose. The speed of ultrasonic waves is dependent on temperature. So before using ultrasonic waves for any measurement we need to calibrate the speed of ultrasonic waves in current atmospheric temperature. For this purpose we have implemented a special algorithm to calibrate the speed of ultrasonic waves through a known distance of 100 Cm.
There are numerous applications of ultrasonic waves in instrumentation and control. These applications include measurement of distance, speed, flow etc. Ultrasonic also find many application in medical instrumentation.
FUNCTIONAL BLOCK DIAGRAM
THE COMPONENTS
• Transducer pair (MuRata, MA40S/R).
• PIC16F873.
• 12MHz Crystal.
• Low power operational amplifiers (LM741).
• Shottky Barrier Diodes (BYV10).
• Low power operational amplifiers (LM358).
• NAND Gates (4011B).
• Inverter (4069UB).
• Transistor (2SA1015, 2SA1815).
• Seven Segment Displays (common anode).
• Several resistors.
• Several capacitors.
CIRCUIT DIAGRAM THE TRANSMITTER PART
Here in this project we use 40 kHz transmitter. This 40 kHz frequency is