Abstract: This paper proposes a signal transforming system of pyrometrc, which program-controlled by 8039, a single-chip microcomputer.
This system is designed to complet higher bit anaiog-to-digital conversion using a 8-bit A/D converter,automatic compensating of zero shift,automatic changing of temperature range, as well as linearity of input voltage.
This system covers the temperature range from 1000℃ to 1800℃, totalled 800℃. The error of the system is less than 1℃. The circuit of signaltransforming and the block diagram of program is given out. There is notany parameter of linearity in the program. It can meet the demand of all kindof input functions. Then, the errors of all parts of the system and its influnces arc discussed. Finally, the results of experiments are given out. A optical fiber pyrometer included the signal transforming system has beenturn out. The pyrometer was calibrated by the blackbody furnace. The result of calibration shows that the maximum error is less than 2℃. The pyrometer has been installed on the blast furnace, which used to measure molten iron.
It is shown that, combining hardware with software, digital circuit with analog circuit, the signal transforming system is more flexible and the construction of the system is simpler. This signal transforming system can meet the demand of the signal inputed, which not only temperature, but also some other sensors.