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一个8421码的计数板,其Q端用以计数,端可取得反馈信号。利用此反馈信号,实现带有小数点的非整数的分频。这种线路很适用于固定分频系数的数字化仪器之中,对于带有小数点的非整数的分频,通常是采用追加法。但它的工作频率随着反馈脉冲数的增加而下降。本文提出一种新的方法——消减法,它除了具有追加法的特点外,其工作频率比追加法高,工作频率不因反馈脉冲的增减而变动。
A 8421-yard counter board, the Q-end to count, the end can get the feedback signal. Use this feedback signal to implement a non-integer fractional frequency with a decimal point. This kind of circuit is very suitable for the digitizing instrument of the fixed frequency division factor, for the non-integral frequency division with the decimal point, usually adopt and add the law. However, its operating frequency decreases with the increase of the number of feedback pulses. In this paper, a new method, subtractive method, is proposed, except that it has the characteristics of additional method. Its working frequency is higher than that of the additional method, and its working frequency does not fluctuate due to the increase or decrease of the feedback pulse.