Data transmission combines methods to convey information from a sender (source of information) to a receiver (information sink). Information conveyed by electrical, optical signals or by electromagnetic waves. Technically, the transmitter transmits the signal in a physical quantity to the receiver and is measured at the end. In electrical signals, an electrical voltage or an electrical current is measured. In optical signals, the light and its difference in colors is measured. In other words, Data transmission is the physical transfer of data from a communication channel point to one point or multipoint. Examples of these channels are twisted pair cables, optical fiber, wireless communication and storage media. Data are represented as an electromagnetic signal, voltage signal, radio waves, microwaves or infrared.
Data Transmission : Basics
In the data transfer, the to be transmitted messages or information is known as data. These data are shown in modern communication technology as a series of bits. A bit is the smallest unit of information or the smallest information carrier, which can assume only two states. These two states are often represented by 0 and 1. But there are also other conflicting state are conceivable. Such as to light on and off. The processing and transmission of data is usually in the form of bit strings.
For the transmission, different transmission routes are available. Copper electrical signal cable may be used. Optical signals are transmitted over fiber optic cable. And for electromagnetic wave, it is the free space (air) which acts as the transmission medium.
The data transfer rate indicates the amount of data that is transferred within a given unit of time via a transmission medium. The time unit is the second. The smallest measure of the amount of data is the bit. The real existing transmission media are both limited in their bandwidth as well as the maximum transfer rate is also subject to various disturbances and thereby has limitation. The bandwidth of the transmission medium determines how many bits can be transmitted per second. Most transmission systems can transmit multiple bits per transmission step. The disturbances during transmission limit the information content per transmission.
To create the best possible conditions for data transmission in electronics and communication engineering, multiplexing and modulation techniques has been developed. Multiplexing method interlace multiple signals in order to use the transmission path more than once. Modulation methods bring the signals in a particular physical form, so that the signals arrive at the receiver as unchanged as possible or at least as identifiable.
The electronics of the data transmission is based on integrated circuits, in turn; consist of highly complex electronic circuits and the number of semiconductor devices. Thanks to the miniaturization of semiconductors, we are able to incorporate extensive functionality in a small space in every electronic device. In communications technology, this highly complex integrated circuits establish the connections between the transmitter and receiver to ensure the highest possible data transfer rate.
Data Transmission : Switching
The circuit switching is to establish a physical connection over several switching stations for the duration of the transmission between the subscribers. The telephone network is based on circuit switching. Each phone call will be transferred to a dedicated line between two participants. The telephone network is designed primarily for the transmission of telephone calls. Over time, the transmission of data becoming increasingly important and the availability of the telephone network has been more and more often for “abused”.
Although a telephone network is also suitable for the transmission of data, but only with technical tricks that could not evolve fast enough to be able to cover the ever-increasing demands on bandwidth. The importance of networking of data and people and the transfer of enormous amounts of data has increased steadily in recent years. With the implementation of the Internet and the transmission of video, audio, and video data, the designed for voice transmission technology has proven to be a bottleneck. The Internet using the World Wide Web and e-mail have demonstrated the importance of data networks with high bandwidth. For this reason, data transmission over the telephone network is a discontinued model.
The telephone networks are designed to handle a small number of short-lasting connections. The telephone network neither has the bandwidth nor the capacity to handle very many simultaneous connections. The possibility of using the telephone network to transmit data is rather an option, as an integrated feature. With ISDN scenario has not significantly changed, even if the stability of the compounds has been much better. In particular, the Internet access through a dial-up access is not technically or economically feasible. To protect the dial up telephone network from overload from rising Internet users, fast alternative broadband access technologies have been developed.
In packet switching, the data or information is divided into packets to store and/or to forward. The service or application passes the individual packets to the communication system and provides the destination address and other information for exchange. The IP technology brings significant simplifications in the network infrastructure.