Abstract:
A method of fabricating couplers in optical fibres for example two fibres (5, 6) forming an X coupler, involves traversing a small flame along the coupling region (7) of the fibres in an oscillatory motion and simultaneously stretching and twisting the fibres to give a symmetrical and smooth biconical taper. The oscillatory motion is performed in such a way that the part of the fibres at the ends of the oscillatory stroke do not become hotter than that part at the centre of the stroke and so either the speed of the flame increases, or the flame moves away from the fibre, towards the ends of the stroke.
Abstract:
To reduce wear on the contact area of contacts of an electrical connector assembly each of the contacts of a male connector of the assembly is provided with a displacement member which is arranged to cooperate with respective contact members of a corresponding female connector of the assembly to displace the contact members during mating of the connectors. In a particular embodiment a printed circuit board (2) carries an attachment in the form of a comb which attachment has a plurality of displacement members (8) respectively arranged to lie alongside printed contact areas (9) of the printed circuit board(2). In use a part (7) of each contact member of a female connector rides up a forward ramp of the respective displacement member (8) travels along a plateau and rides down a rearward ramp after the leading edge of the printed circuit board (2) has passed over the contact area of the respective female contact. Preferably electrical contact between the female contact and the contact area (9) of the printed circuit board (2) is permitted afterthe leading edge has passed overthe contact area but before completion of mating of the printed circuit board (2) to the female connector so as to assist the removal of any film or debris in the respective contact areas.
Abstract:
A solenoid, more especially for use in nuclear magnetic resonance spectroscopy where the coil windings need to be very accurately located, has a multiplicity of elongate elements spaced around and accurately positioned on the outside of a cylindrical former, the elements having locating means, conveniently in the form of slots, which together define a helix and these serve to locate a respective coil winding. The elongate elements support a further layer of elements, also having locating means which serve to locate a further winding, and these elements support further elements and so on to provide required number of winding layers. Means are also described for maintaining the solenoid at a substantially uniform temperature.
Abstract:
A loop-back unit for connection at the subscriber's end of a line (15) to provide a loop-back line testing facility, the unit comprising a transformer (1) with a first winding (3) and second winding (5) of relatively high inductance, connected in series across the line, and a third winding (7). In normal operation the subscriber's unit (17) is connected across the second winding and the transformer is transparent to signals on the line. To test the line a tone is applied to the line which is detected by a detector (25) connected across the third winding and in response to the detector output a control circuit (23) operates a switching arrangement (21) to disconnect the subscriber's equipment temporarily from the second winding and apply a test tone across the second winding. The unit is capable of satisfactory operation despite faults in the subscriber's equipment.
Abstract:
A coupling between an optical fibre (1) and an opto-electronic device e.g. a semiconductor laser (2) is located within a hermetically sealed housing (3,6). The device is supported on a header (14) mounted on the front wall (3) of the housing, the lead (16) to the device passes through the housing wall via a glass-to-metal seal (17,19,20), and the fibre is soldered into a ferrule (10) which is inserted through a boss (4) on the front housing wall. After alignment of the fibre with the device, the ferrule is clamped in position by two parallel sets of screws (11(a),11(b)) inserted through the boss, and is then soldered to the boss. The housing, header, ferrule and metal component(s) of the glass-to-metal seal are all formed of the same metal, preferably gold-plated copper, to avoid differential expansion.
Abstract:
To provide a speech message output from a telephone exchange data defining a number of words and phrases is stored in a data store. On determining the need for a message output a controlling processor selects the data for the appropriate words and transfers the data in the correct order to a synthesiser. The synthesiser outputs complete sentences in pulse-code-modulated form to an output channel of a digital switch. In addition to providing user information as a replacement for (e.g.) engaged tone, number unobtainable etc. the system may be used to provide speaking clock, weather forecast and like facilities. Use of the system in user guidance is also disclosed.
Abstract:
To reduce the quantity of data stored to define visual images electrical signals defining the images are digitised and analysed on a pixel-by-pixel basis to determined boundaries between zones having differing textures and the textures within the zones. Only data defining the zone boundaries and zone textures needs to be stored thus allowing a larger number of visual images to be held in a store than would be possible if full TV data were to be used. An image reconstitutor capable of synthesising signals defining an approximate replica of the original visual image from the data defining the zone boundaries and textures is disclosed. By linking the analysis apparatus and synthesising apparatus using a transmission line an image transmission system is provided.
Abstract:
The position of a fault occurring in an electric power transmission line (1) is determined by "labelling" a voltage or current pulse originating from the fault and reflected by the end of the line, or some other point in the system, moving back towards the fault, and then measuring the time taken from the labelled pulse to return to the measuring point near the end of line. The "labelling" is achieved by predicting from known data and the time of arrival of the reflected pulse the amplitude of the voltage pulse and comparing the prediction with the measured valve. Apparatus for carrying out the method is described.
Abstract:
A motor control system in which an actual torque indication is derived from the motor and compared with a reference, or demand, torque. From the difference signal is derived a stator M.M.F. in magnitude and position relative to a reference frame locked to the rotor. Orthogonal components of this stator M.M.F. are derived and transformed to stator phase winding drive signals.