| 摘要 |
PURPOSE:To always take out a frequency deviation degree as a digital value by using the differential signal of an input signal as an up-count signal and the timing pulse obtained from the center frequency of the input signal as a down-count signal respectively, and applying these signals for procession. CONSTITUTION:A differential signal Fx obtained from a pulse input signal and a timing pulse FC'' produced from the center frequency of the pulse input signal through a production circuit 14 are supplied to a frequency comparator 12 as up- count and down-count signals FUP and FDN respectively. The circuit 12 obtains the difference between both signals and increases and decreases the count value of a 2<m>-notation up/down counter 13 according to said difference and works so that the output of the comparator 12 approximates to zero gradually via a feedback loop circuit containing a complement conversion circuit 17, a rate multiplier circuit 15 and a pulse synthesizing circuit 18. When the output of the circuit 12 goes to zero, the frequency deviation degree of the pulse input signal is obtained to the center frequency based on the output of the counter 13. Thus it is possible to always extract the frequency deviation degree of the pulse input signal to the center frequency in the form of the digital value. |
