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阐述了适用于我国一般的脉冲拨号小型电话交换机上，用单片机控制的计价器的信号采样原理，电路结构与软件设计。现场应用效果证明使用维护方便，抗干涉能力强，效果良好。电话交换机控制各个分机同外线的联系，但在我国一般的电话交换机没有计价功能，用户分机在打外线电话时电话交换机值班人员记录通话时间和计算通话费用比较困难。文内所述的电话计价器可以解决这个问题。
This paper expounds the signal sampling principle, circuit structure and software design that are suitable for the general pulse dialing small telephone exchange in our country. Field application results show that the use of convenient maintenance, anti-interference ability, the effect is good. Telephone exchange control each extension contact with the outside, but in our country there is no pricing function of the telephone exchange, the user ext when making outside calls telephone exchange on duty to record the call time and calculate the call costs more difficult. The telephone meter described in the article addresses this issue.