It would be a good idea to look at some overall systems. Transmitters and receivers are tied together in a number of ways that describe the kind of system rather than the kind of transmitting format used. One of the first questions to come to mind is : In how many directions will the data be transmitted ? This can best be answered by defining the classifications of systems we use today (see Fig. 37.14).
Fig. 37.14 Modes of transmission; simplex, half duplex, full duplex and full/full duplex