During the 1st week at Motorola, I need to have some basic study again which related to this field. When I come across this topic “type of communication” just recall back on my academic study on “Communication Network“, almost the same, just that here, I can get know more detail which does not include in my study.

Radio systems use any of three types of communication: simplex, semi-duplex, and full-duplex. The communication type used depends on the number of users and the type of equipment available. This section provides a description of the three types of communication.

Simplex Communication
The most basic type of radio communication is simplex. Simplex communication consists of radio units operating on a single frequency. Because everyone transmits and receives on the same frequency, users cannot talk and listen at the same time. Simplex means transmission in one direction at a time.

A simplex radio system works well when there are only a few users who are closely located. When additional users are added to the system, the competition for the one available frequency can make it difficult to get a message across. In addition, great distances and natural obstacles such as high hills and tall buildings can interfere with the single frequency.

Do you know: Television Channel and Radio Channel (FM or AM) are using simplex communication type? Which mean we can receive at our television and radio only, while we cannot make respond.

Semi-Duplex Communication
Semi-duplex communication uses two frequencies: one for receive and one for transmit. A radio operating in semi-duplex mode can only transmit or receive at any particular time.

Eg. Walkie Talkie, which only able to transmit 1 way, while another end can transmit after the other end stop.

Duplex Communication
Duplex communication uses different frequencies simultaneously, one to transmit and the second to receive. The transmitter output is isolated and separated in frequency to prevent blocking the input of its companion receiver. Also called full-duplex, this type of operation is used to indicate that the equipment can receive and transmit at the same time. Normally, fixed equipment (a base station) operates in full-duplex mode while mobile equipment typically operates in half-duplex mode.

Eg. Cell Phone and Mobile Phone that able to communicate in both way at the same time.