British Telecommunications Public Limited Company

British Telecommunications Corporation

The Post Office

Raymond C Hooper

Roderick Peter Webb

Paul C Hensel

David R Smith

Signal generation

Optical inverter and logic devices using same with buffer limited

Optical demultiplexer

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

Electronic telephone exchanges and optical fiber links for use therein

A signal level stabilizer includes two amplifier stages, each stage having a respective feed-back loop to control its gain. The gains of the amplifiers are varied in response to variations in the level of the input signal to give a substantially constant output signal. At low levels of the input signal the gain of one of the amplifiers only is varied in response to variations of the input signal and at high levels of the input signal the gain of the other amplifier is varied. The amplifiers may be part of a repeater in an optical communications linkage and one of the amplifiers may then be a photodiode and the other a power amplifier.

Signal level stabilizer

Growing community of inventors

Ipswich, United Kingdom

Raymond C Hooper