Multiplexing and de-multiplexing

Multiplexing and de-multiplexing Multiplexing is a process in which two or more signals are added and one signal is taken out. It has more than one input and a single output.

Therefore, multiplexing is a process in which multiple signals through the same route retain their properties during this process. In this process, a device is used to send all the signals at once, which is called a multiplexer. Therefore, multiplexing is a process in which multiple signals through the same route retain their properties during this process. In this process, a device is used to send all the signals at once, which is called a multiplexer. is called. It is the multiplexer that decides when and how to provide transmission paths to all input signals. The basic signals are then separated by a de-multiplexer at the receiver point.

If many signals are transmitted without multiplexer then various problems occur in transmission and that transmission is difficult. A lot of modems are used in this type of transmission.

But if a multiplexer is used in this type of transmission, then it will work as shown in the picture. In this modem and leased line are used the least, that port of the multiplexer which is connected to the terminal, that port is called terminal port and the port to which the leased line is connected is called line-port. The demultiplexer is already connected inside a multiplexer so that the demultiplexer does not have to be used separately.

Multiplexing and de-multiplexing

Various types of multiplexing techniques are used in multiplexing system, these techniques are of the following types -

Frequency Division Multiplexing (FDM) - FDM is an analog technology when the bandwidth of the link is more than the combined bandwidth of the signal, then FDM is applied in this transmission. In FDM the signals generated by each device are modulated to different carrier frequencies, later these modulated signals are combined into a single composite signal which is transported through the link. A leased line is designed to use a channel with a bandwidth of 300-3400 Hz and a multiplexer is used for this band. In frequency division multiplexing, a bandwidth is taken (which can be transmitted by the communication channel) and it is divided into smaller logical channels and also gives a different bandwidth to each logical channel. All these sub-channels are separated by guardbands

In this process, a different carrier wave is used for each of the small modulating signals which is modulated on the basis of its modulating signals. This type of transmission does not require any type of modem to connect the multiplexer to the line.

Frequency Division Multiplexing

(ii) Time Division Multiplexing (TDM) – It is a digital process which is applied when the data-rate capacity of the transmission medium is more than the data-rate required by the sending and receiving device. In this type of situation, by sub-divisioning the multiple transmissions only a single link is accepted by each TDM uses time slots of a specified size for the sub-channels. A complete cycle of time slots is called a frame.

There are two types of type division multiplexing.

(a) Synchronous time-division multiplexing The term synchronization itself refers to a de-multiplexer, a wall of time slots and frames. The first bit of the first time slot carries the frame of synchronization. If all the sub-channels have the same data bit rate, all the time slots also have the same length.

Time division multiplexing

(b) Asynchronous Time Division Multiplexing - Asynchronous time division multiplexing is also called space division multiplexing or statistical time division multiplexing.

(iii) Wave Division Multiplexing (WDM) – WDM works similarly to FDM but in that multiplexing and demultiplexing keep the light-signal transmission which is transmitted through fiber optic cable. Its idea is similar to FDM but Its frequency is very high.

The WDM multiplexer and DI-multiplexer are shown in the figure. Under this, different types of bands are obtained from different sources. this technique It is quite difficult but its concept is very simple.