An alternative to the analog electromechanical system consists of a micorprocessor (MPU), an analog-to-digital converter, a piezoresistive pressure sensor, and an operational amplifier. In this system, the pressure sensor generates a voltage in response to the pressure applied to it by the liquid in the tank. The pressure is a function of the liquid level in the tank. The sensor signal is converted from analog form into a digital signal by the analog-to-digital (a/d) converter. Most a/d converters require the millivolt sensor output to be amplified. For this reason, an operational amplifier (op amp) is included in the system. The digital signal that the MPU receives from the a/d converter is manipulated so that it can be compared with data in look-up tables, which are stored in ROM. This comparison is used to determine the volume of liquid in the tank. Measurement accuracy depends largely on the number of levels chosen to define the tank and system calibration. The MPU then drives a display, either digital or analog, to show the level of liquid in the tank.
Measuring volumes with microprocessors
Volumenmessung mit Mikroprozessoren
Mach. Des. ; 57 , 20 ; 82-85
1985
4 Seiten, 3 Bilder
Aufsatz (Zeitschrift)
Englisch
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