| 摘要 |
PURPOSE:To simpliy the constitution of a circuit although the number of digits is large for the displayed frequency, by giving a conversion of complement to either one of the reference frequency and the frequency measured after the reference frequency to add these frequencies together and controlling the conversion of complement according to the presence or absence of a carry. CONSTITUTION:The frequency of the output signal of an oscillator 11 is counted by a frequency counter 12, and the desired reference frequency f0 is stored in a storage circuit 13. The complement of f09 of frequency obtained by a complement device 14 is added to the frequency fV which is calculated later through an adder 15. In the case of fV>fO, the output of the adder 15 receives no conversion of complement through a complement unit 16 owing to the occurrence of a carry and is displayed at a display device 17 as it is. While in the case of fV<=fO, no carry is caused. Thus the output of the adder 15 is converted into a coplement of 9 by the device 16 to be displayed at the display device 17. As a result, a number of comparators and switch circuits can be eliminated for each digit to simplify and miniaturize the scale of circuit. |
