| 摘要 |
PURPOSE:To perform signal processing digitally and accurately, by frequency- dividing a carry output of an up-down counter presettable in a phase synchronizing signal generator and making switching control for the up-and down-operation. CONSTITUTION:A presettable counter 11 has a preset input terminal Di and output terminal Qi, a carry output terminal 15 is connected to a frequency divider 16 and also applied to an AND circuit 17 together with an input pulse train P. The output terminal of the frequency divider 16 is connected to an up-and down- switching terminal 14 of a counter 11 for up/down control. When no input pulse P is present, the up/down count of clock pulses at a terminal 13 is repeated every circulation of period and the frequency divider 16 produces a given free oscillating frequency 30Hz. Next, when a pulse train P in frequency 35Hz is incoming, the content of counter is shifted by one bit with the first pulse and it is inputted to a preset input terminal Di for down count, and the frequency divier 16 is switched with a borrow output and the synchronism is achieved by repeating the preset and count sequentially. |
