| 摘要 |
PURPOSE:To obtain a digital value proportional to the inverse sine of an analog signal by subtracting a certain value corresponding to the angular frequency of the analog sine wave signal from the contents of a counter. CONSTITUTION:The timing signal of an analog sine wave signal generator 10 is inputted to a clear terminal CL of a first counter 13, and the counter 13 is cleared once in one period synchronously with the sine wave output. While the output of a comparator 11 is '1' after clearing, the first counter 13 counts the clock signal from a clock generator 12. The counted value is latched in a latch circuit 14, and the first counter 13 is cleared at the same time. The operation is repeated to successively latch the value proportional to a specific period in the latch circuit 14. A microcomputer 15 reads the proportional value from the latch circuit 14 and subtracts a value equivalent to a certain value to obtain the digital value proportional to the sine wave (arc sine) of an analog phase difference signal sinDELTAtheta, namely, DELTAtheta. |
