Half duplex and Full duplex

Half Duplex

A half-duplex (HDX) system provides communication in both directions, but only one direction at a time, not simultaneously. That is to say, the two parties could not send or receive at the same time. The best example of this is the CB equipment that was so popular in the 1970s. People could communicate, but had to press a talk key in order to send a voice message to someone then be open to receiving a voice message in order to hear a response. And the other typical example is interphone. People communicate by interphone as below:
A: Hello, hello, how are you? Over
B: Fine, thanks. And you? Over
A has to say over to receive message after he sent message. So do B.
So, they cannot send or receive message at the same time.

Full Duplex

The full duplex is more advantage than half duplex. That is, the two parties can send and receive message at the same time, just like our telephones. Because it can sent data in both directions, and don't need to switch the direction, there is no time to waste which is very beneficial to those application who can't delay time such as remote monitoring and control system.

Half duplex and full duplex are widely used in fiber optical products. E.g. Dual fiber optical transceivers, including SFP, XFP, SFP+ etc., single fiber optical transceivers and other passive telecommunication devices like CWDM mux/demux, DWDM mux/demux etc. Majority manufactories define a half-duplex as a channel. SOPTO can provide 2channel, 4channel, 8channel, 16 channel and 32 channel CWDM mux/demux and DWDM mux/demux.