公开(公告)号：US4737987A

公开(公告)日：1988-04-12

申请号：US826176

申请日：1986-02-05

申请人： Erwin Haussmann

发明人： Erwin Haussmann

IPC分类号： H04M1/00 ,  H04M19/04 ,  H04Q1/442 ,  H04Q1/446

CPC分类号： H04M19/04 ,  H04Q1/442

摘要： A simple and inexpensive circuit for evaluating the level and frequency ranges of call signals in a telecommunication system. For level evaluation the circuit comprises a pair of oppositely poled threshold value switches and an opto-coupler connected thereto. For frequency evaluation the circuit further comprises at least two series-arranged retriggerable monostable elements whose outputs are connected to a logic circuit. The dwell times of the monostable elements in response to an applied signal establish the frequency range within which a call signal can actuate the output of the logic circuit, thereby indicating whether the signal is within that range.

摘要翻译： 一种用于评估电信系统中呼叫信号的电平和频率范围的简单而廉价的电路。 对于电平评估，电路包括一对相对极化的阈值开关和与其连接的光耦合器。 对于频率评估，电路还包括至少两个串联布置的可再触发单稳态元件，其输出端连接到逻辑电路。 响应于施加的信号的单稳态元件的驻留时间建立了一个频率范围，在该频率范围内，一个呼叫信号可以启动逻辑电路的输出，从而指示信号是否在该范围内。