Calibration and Digital Linearization of Ultrasonic Transducer Response

This paper discusses the calibration and digital linearization method of ultrasonic transducer responses. The system consists of a power supply circuit, a pair of series HC-SR04 ultrasonic transducers (transmitter and receiver), a digital signal conditioning circuit using ATmega16 microcontroller and output monitor using a 16´2 LCD screen. The calibration is done by measuring the water level, and the nonlinearity of ultrasonic transducer responses has been obtained during calibration steps. For linearizing the response, we have performed the segment linearization method and finally we have obtained the fixed nonlinearity equation of transducer responses for all range measurements. The equation of nonlinearity responses is then stored in the microcontroller as a base to respond to the physics input that means the water level. Each physics input that is read by the ultrasonic transducer is further processed digitally by a microcontroller and the results are displayed on the LCD screen. The water level displayed on the LCD screen shows a linear response and is in conformity with the actual value of water level and the theoretical calculation. The average error of calibration and digital linearization compared with the theoretical calculation is 0.299 %. With the system, we can then use directly the transducer to measure and control the water level system