Switching to photonics: voice, video, and data will eventually be switched by hardware that exploits the interplay of photons and electronics

Article Abstract:

Researchers all around the world are developing photonic switching architectures and devices. Two divergent technologies are particular focus points of researchers' attentions: one involves 'guided-wave photonics,' which uses either time multiplexing or wavelength multiplexing in structures such as optical fibers or star or directional couplers, supporting many users on a few channels; and the other is 'free-space photonics,' which uses lenses, mirrors, holograms and arrays of optical logic gates or optoelectronic integrated circuits, supporting fewer users on many slower channels. One way to do guided-wave switching involves time-division multiplexing. Division is accomplished by interchanging time slots or by using devices such as star couplers. Another way involves wavelength division. A design for a wavelength interchanger proposed by NEC is described and explained. Multidivisional fabrics combine space-division and time-division multiplexing techniques. Such devices are still in the planning stages, but it seems that they will be characterized by very large throughputs that require little hardware. An AT&T Bell Laboratories proposal for a time-space-time photonic switch is described. A listing of organizations working on photonic devices together with keyword and phrase indications of kinds of devices being developed is included.

Research, Design and construction, Photonics, Optoelectronic devices, Telecommunication switching equipment, Telecommunications switching equipment, Optoelectronics, Switches, Glossary, Switching circuits, Trends, Outlook, Future Technologies, Scientific Research

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Space Communications: adequate spectrum must be allocated for future space communications and the development of as yet unforeseen technologies

Article Abstract:

Six proposals for improving arrangements for communications relating to space research will be presented at the 1992 World Administrative Radio Conference (WARC-92.). The proposals have to do with the following concerns: extravehicular activities; space operations; data relay links; deep space probes; planetary missions; and earth exploration satellites. Proposals that will be considered at WARC-92 have been reviewed and reconciled by the Space Frequency Coordination Group, which consists of representatives of 30 space agencies. A listing of members of that group is provided. An issue of special importance to most members involves allocation of spectrum in the bands 2.025-2.110 GHz and 2.20-2.29 GHZ, for space research, space operations and earth exploration satellites. For further information about WARC-92, the following documents are suggested: Technical and Operational Bases for the World Administrative Radio Conference 1992 (WARC-92), available from the International Telecommunications Union (ITU), Geneva, Switzerland; 'The 1992 World Administrative Radio Conference: Issues for US International Spectrum Policy,' available from the US Superintendent of Documents; and for amateur radio operators, 'WARC-92: What it Means to You,' by Kirk Kleinschmidt and Paul Rinaldo, QST magazine, Jun 1991, pp 16-18 and p 64.

Radiotelephone communications, Conferences, meetings and seminars, Telecommunications systems, Satellite communications, Discovery and exploration, Outer space, Space exploration, Space flight, Interplanetary voyages, Radio, Amateur radio stations, Conferences and Meetings, Radio Communication, Radio Frequency, International Organizations, World Radiocommunication Conference, World Administrative Radio Conference, Amateur Radio

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