Abstract: In a data transmission system data is sent, after suitable conversion, as a ternary analogue type signal. Using two-wire twisted pairs and hybrids, echo cancellation and feedback equalization are needed. Synchronization between the two ends, e.g. of a 144 Kb/sec. subscriber's loop, is maintained by a low amplitude pilot tone sent with the data, which is detected at the same time as the data is detected. Detection and elimination of this pilot tone use coefficient generation circuitry similar to those used in the equalizer and echo canceller.

Abstract: A method of and an arrangement for the combined correction of I/Q phase and amplitude imbalances within channels and interchannel phase and amplitude mismatches in arrays of signal channels. The I and Q channels of a reference channel are orthogonalized while simultaneously commencing the correction of an auxiliary channel. Optimum correction is obtained with reduction in hardware in comparison with a cascaded correction method, the auxiliary channel I and Q components being transformed only once.

Abstract: A laser chip is mounted on a cantilevered extension of the fibre support tube so it is immune to misalignment forces from the package. Also enables testing prior to packaging.

Abstract: A well structure for a semiconductor device has a dopant profile such that the maximum net dopant level is below the device surface. This is achieved by a two stage doping with materials of opposite conductivity type.

Abstract: Encapsulated optical fibres (FIG. 1A), for e.g. a submarine cable have their encapsulation removed by high velocity hot air blowers (6,7), leave free the acrylate coated fibres for splicing/jointing. An automated equipment moves the blowers progressively along the fibres to free between 0.75 and two meters.

Abstract: An active optical fibre star coupler having a length of amplifying optical fibre (1) optically connected at one end to a wavelength combining coupler (2) and at the other end to via a beam expanding element (3) to a set of output optical fibres.

Abstract: An aerial optical fiber cable comprises a glass-fibre-reinforced plastics core member (1) having a slot (2) with a zero lay angle accommodating loose-tubed optical fibres (3, 3A) and sheathed with a longitudinal tape (13) bound with a binder (915) and over-sheathed with a plastics extrusion (14). The cable is self-supporting and completely non-metallic and is suitable for telecommunications and data transmission services alongside overhead power transmission systems. An alternative embodiment (FIG. 2) is not self-supporting but is similar in design and adapted for support from a support wire, and another embodiment has a rectangular slot housing one or more ribbon elements. The cable is simple and cheap to make.

Abstract: A method of deploying a cable or other line in a fluid transportation pipeline while in normal operation full of and transporting a fluid under a positive pressure. A collapsible centralizing device is attached to the leading end of the cable and is then fed in a collapsed state into the pipeline via a first fluid sealing means at the cable entry position. That device maintains the cable end centralized in the pipeline cross section while the cable is fed into the pipeline. Magnetic sensing means disposed near the cable exit position sense the presence of the cable end and control the cable infeed so as to position the cable end in a predetermined cable retrieval position. A tubular lance is fed into the pipeline through a second fluid sealing means disposed at the cable exit position, and a grab housed in the nozzle of the lance is ejected to engage and capture part of the centralizing device and cable end, whereafter the grab closes on being drawn back into the lance.

Abstract: Bistable switching between clear and scattering states is provided by a liquid crystal cell whose liquid crystal layer is constituted by a random orientation planar aligned ferroelectric smectic exhibiting a pitch length comparable with the wavelength of visible light.

Abstract: A dispenser for use, for instance, as a rumen bolus is a generally cylindrical container (1) for material to be dispersed into the digestive tracts, etc. of a ruminant. The container has a closure (3) held in place by a controlled release glass (CRG) member (5). When this member is dissolved, the closure (3) comes out and the contents are released. The cylindrical container can be formed by a hole in a larger member which has several such holes so that different materials can be released, or materials released at different times.Variants include stacked arrangements in which several dispenser compartments are coupled so that as one is emptied a CRG member is dissolved to release material in the next compartment.In some cases the CRG member acts both as the release device, and as the closure for its compartment, and in others it also acts as a means of linking a number of detachable sections.

Abstract: A method of manufacturing a bipolar transistor (1) with semi-self-aligned p.sup.+ base contacts (27,27a). A p-type base region (28) is formed in a surface region of an n-type region 5 comprising a collector. An element (29) of, for example, n.sup.+ doped polycrystalline silicon, and comprising an emitter, is formed on the surface in contact with the base region (28). The base contacts (27,27a) are formed by implantation and using the element (29) as a mask. An n.sup.+ collector contact (25) is made to the n-tpe region (5).

Abstract: A porous water soluble glass body is formed by sintering powdered glass, compacted to a predetermined density, at a temperature near the glass softening temperature (T.sub.s). The porous body may be impregnated with an organic material for subsequent release at a rate determined by the glass solubility.

Abstract: Optical fibres comprised of a halide glass incorporating color centers, for example fluoride fibres, can behave as a laser or an amplifier when maintained at a low temperature, typically 77.degree. K., and optically pumped. A laser may be comprised by a length of such a fibre (1) wound on a spool (2) and disposed in liquid nitrogen (4), the ends of the fibre are outside of the coolant and associated with input and output mirrors (5,6) which define the extremities of a lasing cavity. An optical pumping signal (7) is provided by a laser (8), for example a Krypton ion laser operating in the visible range. The output of the fibre laser is in the infra-red. Higher gain than with conventional color center lasers is achieved due to the longer interaction length and cooling problems are overcome.

Abstract: An injection laser package having a housing and an optical fiber pigtail extending onto a sub-mount of a mount with the sub-mount being formed of a plurality of thick film layers which incorporate a resistance heating element and etched conductors which are insulated from a narrow solder pad. With the end portion of the fiber in alignment with the injection laser chip, a current is applied to the conductors to heat the sub-mount and melt the solder pad to thereby hold the fiber exactly in alignment with the chip. The portion of the fiber extending between the sub-mount and the inner end of the entrance support tube remains unsupported and thereby flexible so that external stresses on the package housing and, particularly, a support tube do not transfer any strain to the end portion of the fiber so that alignment with the injection laser chip is maintained.

Abstract: A bipolar transistor structure (1) which can be used in an integrated circuit where bipolar (1) and CMOS transistors (2,3) are formed simultaneously on one substrate. In integrated circuit form the material, for example polycrystalline silicon, used for the gates (11,21) of the CMOS transistors is also used for the emitters (29) of the bipolar transistors, the collectors of the bipolar devices are comprised by doped wells (5) in the substrate (4) and the base contacts of the bipolar devices are comprised by regions (27,27a) equivalent to source and drain regions (17,18) of the n-well MOS transistors and bridged by base implants (28). The conventional CMOS processing is modified by the addition of two masking steps and one implant (base implant).

Abstract: An optical sensor device uses surface plasmon resonance to detect the presence of a specific material. A transparent body (12) is coated with a thin gold film (14) which film may be coated e.g. with an antibody material. The arrangement is illuminated with a divergent light beam and light internally reflected from the gold film is detected by a photodiode array (16). The dielectric conditions adjacent the gold film determine the position of the surface resonance angle, this being indicated by a dark area on the detector array.

Abstract: An etching apparatus for the selective etching of e.g. single crystal silicon is described. The apparatus includes a tank for receiving a quantity of liquid etchant, the tank being provided with means for injecting oxygen, nitrogen or mixtures thereof into the etchant. Stirrers circulate the etchant around the bath. Gas injection has been found to improve the quality of the etched product and to provide control of the etching process.

Abstract: A fibre optic gyroscope arrangement having a nulling feedback control loop, the gyroscope including means 40 for varying wavelength of the light source 41 for a predetermined period of time at switch-on of the gyroscope and means for subsequently operating the light source 41 at a fixed wavelength.

Abstract: An optical fiber cable package has a kingwire and a plurality of acrylate primary coated optical fibers all embedded in a one-shot extrusion of low melting point plastic, e.g. Hytrel 40. The fibers have a zero angle of lay. The package is particularly but not exclusively suitable for use in an optical fiber submarine cable.

Abstract: An aerial optical fibre cable for installation alongside a power distribution system is made with a surface-slotted core acting as strength member and armouring and housing a ribbon optical element. The slot is filled with a soft thixotropic water blocking gel. The slot is closed and sealed with a close-fitting cap which is bound in position with a yarn and the core then driven several times around a capstan with the cap facing outward to induce an excess length of ribbon element in the core when it leaves the capstan. Plastics material is then extruded over the core to provide a tight-fitting sheath.