How to deal with coupling problems?
When two machines are connected, the signals travelling from one machine to the other may be routed via various coupling devices. One of the most common devices that couples signals from one machine to another is the capacitor. A capacitor allows a flow of Alternating Current (or Voltage) (AC coupling), but prevents Direct Current from flowing between the machines. A transformer essentially does the same. The “cleanest” and most transparent way to route a signal from one machine to another is DC (Direct Current) coupling, where one machine transfers all the components of the signal – the AC component as well as the DC – to the other machine, thus assuring full bandwidth and highest signal fidelity. Professional audio and video equipment is usually DC coupled, for best signal transfer. Direct Coupling in video assures best signal quality, stability and color transfer. In many cases though, due to lack of universal standardization, Direct Coupling between machines may be troublesome and
