N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 2 - Data Communications Basics and Legacy Technologies                                                 Slide 9 of 45 _________________                                                                                  __________

                               Building Blocks - Data Transmission Modes

                                              Simplex          

                                              Half-Duplex    

                                              Full-Duplex      

_________________                                                                                  __________

The information depending on the nature of the application is transmitted either in Simplex or Half-Duplex or Full-Duplex mode.

Simplex Mode Transmission - A communications system or equipment capable of transmitting in one direction. TV broadcasting on the cable systems initially was designed for one-way transmission. The Radio transmission system is another example of a simplex communications system.

                               
                                                    Simplex Mode

Half-Duplex Mode Transmission - A communications system or equipment capable of transmitting in both directions but transmits in one direction at a time. The low speed (1200 bps/2400 bps) data phone transmission systems are half-duplex.

                               
                                                             Half-Duplex Mode

Full-Duplex Mode Transmission - A communications system or equipment capable of transmitting in both directions simultaneously. T-1 systems, present cable network (Internet service) and ADSL network (Internet service) from the telephone companies are examples of full-duplex mode transmission.

                               
                                                             Full-Duplex Mode