It is the purpose of this book to seek to identify at least some of the scientists, mathematicians and engineers whose contributions can each be seen, in retrospect, to have provided an essential key or stimulus to the major developments that followed in later years, and to assess the significance of their individual contributions. However, while some of these innovators may have been inspired by visions of the future, it is certain that very few if any can have foreseen the immense impact that their work has had, and will continue to have, on telecommunications in the 21st century and beyond. In selecting those on whose work attention has been focused, it has to be recognised that one may be doing less than justice to those who were providing the background from which those creative ideas grew, and to those who pursued those ideas to practicality and commercial success - and of course, judgement as to what is a major and specially significant contribution may itself be highly subjective.

This chapter deals with: visual telegraphy; the electric telegraph; the printing telegraph; duplex, quadruplex; time-division multiplex telegraphy; under-sea telegraph cables; and trans-Atlantic telegraph cables.

This chapter discusses long-distance wire and radio communication.

This chapter discusses the evolution of radio communication.

This chapter discusses the history of television broadcasting and electronic television.

This chapter discusses microwave radio relays.

The better understanding of the nature of information, e.g. as conveyed from a sender to a receiver by telephonic speech, a facsimile picture or a television programme, and the development of theories providing a quantitative approach to design have been vital for progress in the evolution of more efficient telecommunication transmission and broadcasting systems. The initial, and major, steps forward were the work of a few innovative and far-sighted individuals in the the laboratories of the ATT Company in the USA, Standard Telephones and Cables Ltd in England and the International Telephone and Telegraph Company in France.

The ability of Earth-orbiting satellites to provide, economically and reliably, direct high-quality communication between any two locations on the earth's surface, and direct broadcasting coverage over large areas, has expanded enormously the scope and volume of these services. The technical advantages were obvious enough. For telecommunication links only one repeater was required, i.e. in the satellite, compared with the many repeaters on long land and submarine cables, and land microwave radio-relay systems, with substantial gains in reliability. For direct broadcasting to homes large areas could be covered by a single transmitter in the satellite, without encountering the 'shadow' areas created by hills and mountains when using ground-based transmitters.

Development of a transmission system offering greater communication capacity at lower cost than existing media such as coaxial cable and microwave radio-relay systems, in a mechanically flexible and compact form that could readily be used in the field is reported. Hair-thin glass fibres transmitting coherent light offered the possibility of almost unlimited communication capacity. The refractive index of the core needs to be about 1 % above that of the cladding and the glass fibre should be of a low-loss dielectric material.

The advances in telecommunications outlined in earlier chapters have removed the barrier of distance and reduced the costs of transmission so that users and databanks can be remote from one another. The microchip has enabled vast amounts of data to be stored, rapidly processed and accessed at costs that continue to fall. It is now clear that information technology will have an increasing influence on the way people live and work, the quality of their lives and the economic prosperity of nations. By reducing the need to travel to communicate the environment itself may benefit.

Mobile radio-communication may be described as communication with and between individuals who may be in land vehicles, ships, trains, or aircraft, via telephone, text, facsimile, e-mail or other services.