Multiplexing Meaning
Multiplexing is that the method of permitting multiple signals from totally different sources to share common channel. that's one channel is employed by totally different signal sources to send their signals.
Multiplexing and its Types
Some types of multiplexing are:
(a) TDM (Time Division Multiplexing
(b) FDM (Frequency Division Multiplexing)
(c) WDM (Wavelength Division Multiplexing)
(d) CDM (Code Division Multiplexing
TDM: In TDM signals area unit separated in time domain. Signals from varied sources area unit allowed to flow through the common line one at a time for fastened time. Suppose there area unit four signal sources, then every signal supply are allowed to use line for a amount t. Once all signal sources transmit for amount t, the primary one once more get likelihood so on.
FDM: In FDM signals area unit separated in frequency domain. Signal from every supply is modulated to totally different frequency in order that the frequency spectrum once modulation won't overlap. At receiving finish, signals area unit demodulated. (i.e. translated back to original frequency).
There are many sorts of multiplexing techniques. Out of which, we've the most types with general classification, mentioned within the above figure. allow us to take a glance at them individually.
Analog Multiplexing
The signals utilized in analog multiplexing techniques are analog in nature. The analog signals are multiplexed consistent with their frequency (FDM) or wavelength (WDM).
Wavelength Division Multiplexing
Wavelength Division multiplexing (WDM) is an analog technique, during which many data streams of various wavelengths are transmitted within the light spectrum. If the wavelength increases, the frequency of the signal decreases. A prism, which may turn different wavelengths into one line, are often used at the output of MUX and input of DEMUX.
Example − glass fiber communications use WDM technique, to merge different wavelengths into one light for communication.
Digital Multiplexing
The term digital represents the discrete bits of data . Hence, the available data is within the sort of frames or packets, which are discrete.
Synchronous TDM
In Synchronous TDM, the input is connected to a frame. If there are ‘n’ number of connections, then the frame is split into ‘n’ time slots. One slot is allocated for every input line.
In this technique, the rate is common for all signals and hence an equivalent clock input is given. The MUX allocates an equivalent slot to every device in the least times.
Asynchronous TDM
In Asynchronous TDM, the rate is different for every of the signals and a standard clock isn't required. If the allotted device for a slot transmits nothing and sits idle, then that slot are often allotted to a different device, unlike synchronous
This type of TDM is employed in Asynchronous transfer mode networks.
De-Multiplexer
De-multiplexers are wont to connect one source to multiple destinations. This process is that the reverse process of multiplexing. As mentioned previously, it's used mostly at the receivers. DEMUX has many applications. it's utilized in receivers within the communication systems. it's utilized in arithmetic and logical unit in computers to provide power and to expire communication, etc.
De-multiplexers are used as serial to parallel converters. The serial data is given as input to DEMUX at regular interval and a counter is attached thereto to regulate the output of the de-multiplexer.
Both the multiplexers and de-multiplexers play a crucial role in communication systems, both at the transmitter and therefore the receiver sections.
In any communication system, during the transmission of the signal or while receiving the signal, some unwanted signal gets introduced into the communication, making it unpleasant for the receiver, and questioning the standard of the communication. Such a disturbance is named as Noise.
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