Figure 10-1 illustrates what we sometimes call a general communications model. Any time there is a communication, we can think in terms of there being (a) a sender of that communication, (b) a message that is being sent, (c) the media over which the message is being sent, and (d) the (intended) receiver of the message.
Figure 10-1. A general communications model.
For example, at this moment you are reading something “sent” by Doug Brooks, author of this book. The message is what is written on this page. The media is the page you are reading, and the receiver is you, the reader.
On PCBs, ...