Improvements in or relating to electronic telephone exchanges and optical fibre links for use therein.

摘要

An electronic telephone exchange of the type employing time-space-time switching, has an optical fibre data link connecting the space (3) and time switches (2,4). In order to meet the design requirements for use in a telephone exchange, the fibre optic link has to have fairly well defined performance parameters. In particular the overall diameters of the optical fibres (16) employed in the optical fibre link lies between 180 and 250 microns, preferably 200 microns, and the core diameter of the optical fibres (16) lies in the range 0.6 to 0.95 of the cladding diameter. Preferably the core diameter lies in the range 160 to 180 microns. The optical fibre link is characterised by the numerical aperture of the fibre, insertion loss of the fibre, sensitivity and dynamic range of the receiver (19) and the power output and extinction ratio of the transmitter (13).