Digital Audio Is Compact and Rugged
Article Abstract:
Compact-disk digital audio systems provide dramatic performance with a recording dynamic range of ninety decibels, error-correcting code for audio with few errors and perfect maintenance of recorded pitch. A compact-disk has more than 20,000 tracks within thirty- three millimeters of its sixty millimeter radius. Information is recorded in tiny pits. The optical pickup system consists of a laser diode, a detector, a collimator lens, and a polarization beam splitter. A tracking servo system ensures precise tracking, and a constant-linear-velocity servo keeps the disk moving at the correct velocity throughout playing. An 8-to-14-bit modulation scheme allows a higher density of data on the disk. The cross Interleave Reed Solomon Code copes with random and burst errors on the disk. Control codes on the disk enable the user to access virtually any bar of music on the disk. Prices for players and disks are expected to drop in the future. Diagrams illustrate various of the player and disk technologies. A table compares the characteristics of a compact disk system and a conventional LP system.
Publication Name: IEEE Spectrum
Subject: Engineering and manufacturing industries
ISSN: 0018-9235
Year: 1984
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Telephone Nets Go Digital
Article Abstract:
The development of integrated-services digital networks (ISDNs) will give telephone users digital communication links for voice and data communication through a set of standardized interfaces. Economics and flexibility are the reasons for establishing ISDNs. A small family of standard interfaces will be provided for all users to accommodate the various applications, which include imaging, audio applications, voice transmission, and bulk data transmission. Software-controlled switches, called stored-program- controlled (SPC) switches, already supply most of the capability needed for ISDN circuit switching. Capabilities soon to become available include circuit-switched digital capability (CSDC), local-area data transport based on packet switching, and the packet transport network. Other countries are also moving towards digital telecommunications networks. Diagrams illustrate the technologies and a table predicts progress in ISDN capabilities.
Publication Name: IEEE Spectrum
Subject: Engineering and manufacturing industries
ISSN: 0018-9235
Year: 1983
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Opening Europe's telephone business to competition
Article Abstract:
The member-countries of the European Union issued on Jan. 1, 1998, a joint decision calling for the deregulation of member states' respective telephone businesses. The move seeks to establish for the European region one harmonized telecommunications market. The ruling also seeks to open market competition between new and existing firms in the telecommunications industry, such as power and rail companies, Internet-service providers, managed-network-service providers, former monopolies on telephone service, foreign telecom-service providers and cable-television operators. Thirteen member-countries of the European Union are set to deregulate their telephone market by the end of 1998, with the deadlines for Greece and Portugal extended until Jan. 1, 2001, and Jan. 1, 2000, respectively.
Comment:
EU: Member-countries issue on 1/1/98, a joint decision calling for the deregulation of their respective telephone bsns
Publication Name: IEEE Spectrum
Subject: Engineering and manufacturing industries
ISSN: 0018-9235
Year: 1998
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