| 摘要 |
PURPOSE:To obtain a electric power ratio with high accuracy by measuring the electric power ratio by using one logarithmic detector on a time-division basis, converting its output from analog to digital, and compensating the nonlinearity of the logarithmic detector by using a conversion table in a ROM. CONSTITUTION:Inputs 11 and 12 are switched and selected alternately by a high frequency switch 14 at a constant period, their outputs are detected by the logarithmic detector 15, and stable parts of detector outputs of the inputs 11 and 12 are extracted and digitized by an AD converter 19. The conversion table 20 for compensating the nonlinearity of the logarithmic detector 15 is written in the ROM and outputs correct logarithmic values of input levels. Its output is delayed by a register 21 and the output corresponding to the input 11 and the output corresponding to the input 12 are supplied to a digital subtracter 23 at the same time, so that their difference is stored in a register 23. Consequently, the logarithmic value of the electric power ratio of the two inputs is found in digital form.
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