Abstract: 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.

Abstract: A device for severing a dielectric optical waveguide comprising knife means, means for clamping a dielectric optical waveguide in closely spaced relationship with said knife means and an anvil which is movable towards said knife means. The anvil is so arranged and constructed that, in use, as it moves towards the knife means, it engages a dielectric optical waveguide clamped by said clamping means and urges it towards the knife means. When the waveguide comes into contact with the knife means it is under a given stress and has a predetermined configuration. The device also includes means for effecting movement of the anvil.

Abstract: A cable comprising a disc insulated coaxial structure in which said discs are designed with notches in which are located optical fibres extending parallel with the inner conductor of the coaxial structure. An insulating keeper wire is forced into the notch to prevent the free fibres escaping therefrom. One or several fibres are contained within each notch.