Usually, when it comes to serial interfaces, especially used in Video Over Fiber transmission product range, for features like PTZ control for camera’s tilting and zooming, questions about Simplex, Half Duplex and Duplex comes out. It is also important in Ethernet physical transmission. This is why this post, and we hope you find it helpful!
Any type of data transmission can be characterized by the direction of signal. The simplex transmission is the one that travels in only one direction. It can be more clear on the example of person talking into microphone and then hearing voice from the speaker. Signal travels in only one direction from microphone to speaker. This way of transmission can be also called unidirectional or one-way transmission.
The half-duplex transmission is capable of sending signal in both directions, but in only one direction at a time. Some networks use half-duplex transmission, but it is required to specify this requirement for all the nodes in the network. An example could be police car radio phones allowing one person talk at a time.
Last, and most common way of transmission is full-duplex (or just duplex). It allows signal transmission in both directions simultaneously. An example is a telephone IP service. This type of transmission can also be called bidirectional transmission.
Most of data networks are using duplex transmission while using different channels in the same medium that connects transmitter and receiver. If the channels are physical and not logical, transmission uses separate wires for transmission and reception. Each of the channels is half-duplex, but together it makes full-duplex. The use of full-duple increases data transmission rate. Modern network interface cards are configured for full-duplex support by default.
However, if we take example of Video Transmission, for example used by this video transmitter over fiber, then video signal will be simplex, and go in a direction from transmitter to receiver, while data signal if used for PTZ, will also be simplex, but go in opposite direction from receiver to transmitter. It is because usually it will be connected to a controlling device.
