An accurate electronic device for ultrasonic measurements using a microcontroller

In the last years, the ultrasonic wave techniques, has attracted a considerable intention in most fields as in the quality control of the agro alimentary products, in medicine, pharmaceutical product, electronic components, oceanography and others. The determination of the propagation velocity of the sound waves makes possible to deduce the physical and chemical characteristics of the sample such as density, compressibility coefficients and viscosity. The ultrasonic velocity, which depends on the temperature, is one of the most employed parameters in these techniques. We use in this work the flight time to determine the ultrasonic velocity. An electronic device has been developed using a microcontroller (/spl mu/C) of the ST62xx family, DS0026 high-speed MOS driver, AD590 sensor and Peltier thermo electric cooler, for the temperature control of an ultrasonic cell. The microcontroller has a clock of 8. We programmed this timer to generate an alternative impulse of a 0.2 /spl mu/s width and a 1 ms period. Two ultrasonic transducers having 5 MHz resonance frequency have been used to send and receive the electronic impulse through a liquid medium. The two piezo-electric transducers constitute the normal bases of the ultrasonic cell. Data-processing programs were developed and charged in the microcontroller, in order to calculate the command law and to generate electronic signals with variable cyclic ratio, which control the power electronics. We use automatic algorithms, to have a precision on the temperature measurement of about 0.1 /spl deg/C. We present acoustic velocity measurements of the agro-alimentary liquids using the realized device.