Common impedance coupling:Because the current flows through the common impedance between the loops,the voltage drop generated by the current in one loop affects the other loop.Common coupling impedances,such as power leads,ground and common power lines on a printed circuit board,bus bars,etc.,are common in computer control systems.These busbars all have a certain impedance,which is the common coupling impedance for multiple circuits.When a large digital signal current flows,it acts like an antenna,introducing interference into each loop.At the same time,there is a capacitance between each return strip,and digital pulses can be coupled through this capacitance.The ground on the printed board is essentially the common return line.Since it still has a certain resistance,signal coupling is generated between various circuits through it.
公共阻抗耦合：是由于电流流过回路间公共阻抗，使得一个回路的电流所产生的电压降影响到另一回路。在计算机控制系统中，普遍存在公共耦合阻抗，例如，电源引线、印刷电路板上的地和公共电源线、汇流排等。这些汇流排都都具有一定的阻抗，对于多回路来讲，就是公共耦合阻抗。当流过较大的数字信号电流时，其作用就像是一根天线，将干扰引入到各回路中。同时，各回流条之间具有电容，数字脉冲可以通过这个电容耦合过来。印制板上的地，实质上就是公共回流线，由于它仍然具有一定的电阻，各电路之间就通过它产生信号耦合。
1/2″ Fisher Controls Type EZ Control Valve 546 Type 65
1/2″ Fisher Controls Type EZ Control Valve Type 657 Si
Rosemount 3051 CG 4A Transmitter with diaphragm D1
Rosemount 3051 CD 1A Smart Hart Pressure Transmitter w/
Rosemount 3051 CG 4A Smart Pressure Transmitter with
Rosemount 3051 CG 4A Smart Hart Pressure Transmitter w/
Rosemount 3051 CG 4A Transmitter w/ Diaphragm F11
