Introduction to Types of Multiplexing
In data-driven systems, an optical multiplexer is defined as a device that integrates and transmits several signals through a single data link.
These signals are then sent to the demultiplexer unit for separating and delivering relevant information to corresponding nodes.
This whole process is known as Digital Multiplexing. Devices such as BRBK, NAMC-SDH, and Sony optical multiplex units are some of the commonly used multiplexers worldwide.
Both analog and digital signals can be transmitted through multiplexers. However, it uses different variations for performing both signals.
For instance, two variations, including FDM (Frequency Division Multiplexing) and WDM(Wavelength Division Multiplexing), are used for analog signals. At the same time, time-division multiplexing is used for digital signal processing.
There are two types of multiplexing, which we have also discussed in short above, digital and analog.
Among those, digital is classified as time-division multiplexing, and analog is classified into two categories, frequency division, and wavelength division multiplexing.
Let’s discuss these types in detail below:
Analog multiplexer only works for analog signals and is generally of two types:
Frequency Division Multiplexing (FDM)
The most commonly used multiplexing technique is frequency division. In this type of multiplexing, the signals are transmitted over different frequencies over different carriers.
There is a special technique used to separate these varied signals to avoid overlapping—for instance, television.
We can view a number of channels through just a single wire attached to our TV because television signals use the FDM technique for signal transmission.
The projecting of signals can only be possible because of the guard band that is created due to unused bandwidth between separating the carries.
The bandwidth of the transmission signals must be greater than the combined bandwidth of all signals for frequency division multiplexing to be a success.
Wavelength Division Multiplexing (WDM)
Wavelength division multiplexing is used for fiber optic communication only, and the power of frequency transmission is relatively higher than FDM.
However, both work on the same principle. You can transmit higher frequencies through fiber optic signals, and if you are going to use it for fewer transmissions, you are wasting its bandwidth.
Therefore, use a WDM to transmit broader signals through a single link, and then a demultiplexer separates the signals and transmits them to the corresponding nodes. For instance, optical fiber communications used in internet connections.
Digital multiplexing is defined as the technique of transferring discrete signals having bits of information in the form of packets or frames. It is further classified in one type- Time Division Multiplexing. Let’s discuss it in detail.
Time Division Multiplexing
In Time Division Multiplexing, the signals are combined first and then transmitted under a fixed time interval.
Each input is divided into slots, which are streamed and multiplexed over an individual data link. It has further two variations: Synchronous and statistical TDM.
Synchronous Time Division Multiplexing(STDM)
Under Synchronous TDM, the sources are divided into equal time intervals even if they are not sending any signal.
You can send data n times at a faster rate with this multiplexing technique. However, when there is no data in any of the sources, then this technique is ineffective. Asynchronous removed this inefficiency.
Asynchronous Time Division Multiplexing(ATDM)
Asynchronous TDM is a statistical slot allocation technique under which slot allocation is dynamically distributed. For instance, if only one slot has data to send over, then only that slot is allotted the time frame.
How Does Multiplexer Work?
All multipliers transmit several signals through a single link and use different techniques as per the type of multiplexer discussed above. Among all, Sony Optical Multiplex Unit is one of the most used multiplexers in the digital world.