Digital Multiplexingĭigital multiplexing is applied to the digital signals DWDM multiplexes a large number of signals by spacing them very close to each other. dense wavelength division multiplexing which incorporates more number of signals over a single communication line compared to standard WDM. Multiplexer and demultiplexer can be built using this principle. The WDM is based on the basic principle of physics as we know that when any light falls on the prism it bends the light beam depending on its angle of incidence and its frequency. So using WDM, the narrow band of lights are multiplexed to make a broader band of light and is transmitted over the single link to the receiver where demultiplexer separates the light signal and deliver to the corresponding node. If you transmit only one optical signal then you are literally wasting the rest of bandwidth of the optical fibre. The fibre optic cable is capable of transmitting data at a high rate as compared to the metallic transmission cable. The Wavelength division multiplexing work on the basic principle of FDM the only change is that WDM is used for fibre optic communication and the frequencies of the signals to be combined is comparatively very high. These three information signals are modulated over a different carrier frequencies and these modulated information signals are multiplexed and transmitted over a single link.įrequency division multiplexing is possible only when the bandwidth used for the transmitting multiple information signals is greater than the combined bandwidth of all information signals that are to be transmitted.Ģ. In the figure below you can see that we have to mux three information signals from channel 1, 2 and 3. This is because of guard band, that the bandwidth of multiple signals over a single link does not overlap each other. The separation between the carrier frequencies leaves an unused bandwidth which we call as a guard band. The best example of FDM is a television signal, you can observe that you can view multiple channels with different frequencies through a single cable.
![compare digital techniques and multiplexing techniques compare digital techniques and multiplexing techniques](https://ars.els-cdn.com/content/image/3-s2.0-B0122272404001167-gr9.jpg)
The carrier frequency of each signal is separated in such a way that the bandwidth of each signal does not overlap each other. In frequency division multiplexing signals are modulated over different carrier frequencies. Analog MultiplexingĪnalog multiplexing is specially designed for the analog signals.įrequency division multiplexing is the familiar & commonly used multiplexing technique. However, the digital multiplexing is classified to time division multiplexing (TDM). The analog multiplexing can be further extended to frequency division multiplexing (FDM) and wavelength division multiplexing (WDM). Multiplexing can be classified into two types Analog Multiplexing and Digital Multiplexing. In the further section, we will discuss types of multiplexing. Demultiplexer separates the multiplexed data stream and delivers it to the corresponding output line. So, using multiplexing you can utilize the bandwidth of the medium by transmitting several signals over that single medium. A multiplexer combines several signals and transmits it over a single link which is accepted by the demultiplexer. Consider that the medium connecting two devices has greater bandwidth than the required, in that case, the bandwidth of the medium is wasted.Īn efficient system must always utilize all its resources.
![compare digital techniques and multiplexing techniques compare digital techniques and multiplexing techniques](https://d3i71xaburhd42.cloudfront.net/ff3ed5eedd7d42176239cddecb4129f4ab201fcb/6-Table1-1.png)
Multiplexing is a technique of utilizing the bandwidth of the medium connecting two devices. In this content, we will discuss multiplexing and its types in brief. And on digital signals, time division multiplexing is performed. frequency division multiplexing (FDM) and wavelength division multiplexing (WDM). For analog signals, multiplexing has two variations i.e. Multiplexing can be performed on analog as well as digital signals.