Multiplexer and Multiplexing Techniques
A multiplexer, also known as data selector, is a device that selects one of several analog or digital input signals and forwards the selected input into a single line. Multiplexers are mainly used to increase the amount of data that can be sent over the network within a certain amount of time and bandwidth.
The multiplexer acts as a multiple-input and single-output switch. Multiple signals share one device or transmission conductor such as a copper wire or fiber optic cable.In telecommunications, the analog or digital signals transmitted on several communication channels by a multiplex method. These signals are single-output higher-speed signals. A 4-to-1 multiplexer contains four input signals and a 2-to-1 multiplexer has two input signals and one output signal. Multiplexers are flexible and often work together with a variety of other devices including a demultiplexer. A demultiplexer or a demux is a device that requires transforming a single input signal to multiple data output lines.
The technique of transmitting multiple signals over a single medium is defined as multiplexing. It is a technique showed at physical layer of OSI model. Multiplexing can be divided into three types: frequency division multiplexing (FDM), wavelength division multiplexing (WDM) and time division multiplexing (TDM).
● Frequency Division Multiplexing
Frequency Division Multiplexing is a technique which uses various frequencies to combine many streams of data for sending signals over a medium for communication purpose. It carries a frequency to each data stream and later combines various modulated frequencies for transmission. Television Transmitters are the best example for FDM, which uses FDM to broadcast many channels at a time.
● Wavelength Division Multiplexing
Wavelength division multiplexing (WDM) is analog multiplexing technique and it modulates many data streams on the light spectrum. This multiplexing is used in optical fiber. It is FDM optical equivalent.Numerous signals in WDM are optical signal that will be light and were transmitted through optical fiber.WDM similar to FDM as it mixes many signals of different frequencies into single signal and transfer on one link. Wavelength of wave is reciprocal to its frequency if wavelength increase then frequency decreases. Several light waves from many sources are united to get light signal which will be transmitted across the channel to the receiver.
● Time Division Multiplexing
Time division multiplexing (TDM) is essentially the time-based switching of multiple analog or digital input signals. In TDM, each input signal (or data stream) is assigned a fixed-length time slot on a communication channel. Each sender transmits a block of data during its assigned time slot. Time division multiplexer is a kind of multiplexer which joins data streams by allotting every stream a different time slot in a set. It frequently transfers or sends various time slots in an order over one transmission channel. TDM attaches PCM data streams.
Multiplexer are used in various fields where multiple data need to be transmitted using a single line. Following are some of the applications of multiplexers:
Communication system – Communication system is a set of system that enables communication like transmission system, relay and tributary station, and communication network. The efficiency of a communication system can be increased considerably using multiplexer. Multiplexer allows the process of transmitting different type of data such as audio, video at the same time using a single transmission line.
Telephone network – A multiplexer is used in telephone networks to integrate the multiple audio signals on a single line of transmission.
Computer memory – Multiplexers are used to implement huge amount of memory into the computer, at the same time reducing the number of copper lines required to connect the memory to other parts of the computer circuit.
Transmission from the computer system of a satellite – Multiplexers can be used for the transmission of data signals from the computer system of a satellite or spacecraft to the ground system using the GPS (Global Positioning System) satellites.
Optical multiplexer is popularly with telecommunication operator and suitable in business for communication operator, government and kinds of entities. It is one of the most popular transmission equipment in point-point fiber optic network. Fiberstore supply a wide range of optical multiplexers, including video multiplexers, video & data multiplexers, video & audio multiplexers, PDH multiplexer, etc. These multiplexers are highly manageable and accompanied by a network management system for configuration, service, performance, security, and fault management that enable cost-effective and efficient transport.