Field Trial of Optical Fibre Cable-TV System Optical Fibre System for ...

Trial of Optical Fibre Cable-TV
System
Kurt Bergsten and Gerhard Gobi
The Swedish Telecommunications Administration and Ericsson are jointly
carrying out a field trial with optical fibre cable-TV. Ericsson has developed and
supplied the digital transmission system used between the main centre and
subcentres as well as the equipment for the analog subscriber lines. The optical
fibre cable used in the trial was also made by Ericsson.
The authors describe the objectives and scope of the field trial and consider the
future development in this engineering field.
UDC 535.394:621.397.74.001.55
optical links
testing
digital communication systems
cable television
isdn
frequency division multiplexing
Fig. 1
Broadband video, audio, data and text
communication network
HC
UC
Head end
Subcentre
Modern telecommunication networks
are heading towards service integration,
with the conversion into digital networks
with transmission over glass fibre
being a major step in this direction. Television
programs will also be transmitted
over such networks in future. The Swedish
Telecommunications Administration
and Ericsson decided to test digital
transmission of picture and sound over
optical fibres by carrying out a field trial
of a newly developed digital, optical
fibre transmission system within the
framework of a cable-TV project for
Skarpnäck, a new suburb near Stockholm.
The Telecommunications Administration's
activities in the field of cable television
form part of its long-term work to
establish service-integrated broadband
local networks. Such networks, unlike
present-day cable-TV networks, will be
based on optical fibre technology and
have a star-shaped structure in order to
facilitate integration with other services,
such as narrowband ISDN, videotelephony,
television conferences and
data transmission. These networks will
also facilitate the introduction of interactive
video services such as teleshopping,
telebanking and access to video
libraries via home terminals. It may
therefore be foreseen that coaxial cables
will gradually be superseded by
fibre cables, starting at the higher levels
of cable-TV networks, i.e. in trunk and
primary networks. As costs go down
fibre cables will be used increasingly at
lower levels-and in the nineties it is likely
that the fibre cable and digital techniques
will be used right up to the subscriber's
termination unit in the home.
In 1982 the Swedish Telecommunications
Administration and Ericsson started
a joint development project for the
implementation of the field trial. The
project was aimed at field tests with optical
fibre cable between a head end at the
Farsta automatic exchange and a sub-