Introduction about Time Division Multiplexing (TDM)
Time division Multiplexing is the digital or analog type of technique in which two or more signals are transferred as sub-channels in one communication mode. The time domain is categorized into various time slots. Data block or sample byte of sub channel 1 is transmitted at the time of time slot 1, sub channel 2 is sent at the time of time slot 2 etc. At the last time slot transmission, the cycle begins again with new data block frame.
How TDM works:
For TDM transmission, both sources are either analog or digital devices so that it can convert data streams in to time slots with the use of PCM. Time division multiplexing uses carrier signals to transfer data stream in sequence where source and destination devices share same single channel.
It uses two techniques for analog or digital transmission.
Human voice is travelled in the continuous form in the range of 0-4 khtz while digital signals runs in discrete forms like 0 and 1. For transmission on network medium, human voice should be converted into streams bits. The conversion from analog to digital is performed with the use of sampling wave and the level of wave when data is transmitted over digital link.
There is attached circuit at the end of transmitting source that is known as multiplexer. It gets output from end user and transfers signal into segments and assigns them composite signal in rotating form. These composite signals contain data received from various users. At the other end of cable, the signals are separated with the use of a circuit that is known as demultiplexer. Then these signals are routed to proper users. In two ways communication, a multiplexer or demultiplexer must be attached with circuit at the end of high bandwidth wire.
TDM technologies are used for the maintenance of the public switched telephony network that is also known as access network of TDM. These telephony switches has compatibility with TDM in some formats like E1 TDM, DSO T1 and BRI TDM. T1 TDM gives you a 1.544 Mbps link of communication that is divided into 24 time slots of 64 kpbs and channel of 8kbps for maintenance and synchronization. E1 TDM gives you 2.0 Mbps link that is found in 32 time slots of 64 kbps. T1 and E1 were first used by different telephony firms to transfer digital voice as there is not much difference between E1 and digital data. T1 TDM is now commonly used for wide area links. Switch Basic Rate provide support to the BRI TDM that is used for data channel and Basic rate of internet service provider network for various static PPP links. Basic Rate interface contains two time slots of 64 kbps size while TDMA is ideal for mobile communication in cell phone network.
Time division multiplexer is used for TDM that combines slow speed data streams into high speed data block or stream. Data is gathered from multiple sources and broken it into different sections and transmitted in accurate sequence. These input data stream has becomes a time slice in form of output stream. The transmission order is maintained in such a way that it can reassemble input stream at the destination side. This device can also work in reverse order with the use of TDM techniques like decomposing high speed data streams into low speed and de-multiplexing process. Therefore, time division multiplexing or demultiplexer work in the same manner.
Benefits of TDM:
TDM technology delivers services to customers that fit to their budget and needs. There are some benefits of TDM that make it the best choice for efficient data transfer.TDM share link between various stations in data communication that supports network medium to make use of the specific link in accordance to their needs.TDM utilizes the link in efficient way to transfer data at high speed. It is ideal for digital data transmission.
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