Abstract: A switched beam antenna comprising several spiral arms with a common axis of rotation and respective inner ends angularly spaced around a common circle generates high gain directional beams at an angle away from the antenna axis. Beam scanning is accomplished by rotating the feed to the arms by means of a commutator circuit. Intermediate beams may be generated by feeding two adjacent antenna terminals simultaneously but with an appropriate phase shift. A comparator may be provided to compare signals from several arms and select the arm yielding maximum signal strength.

Abstract: A suspended ceiling system which uses only two components to form main beams of an inverted T-shaped cross-section, cross beams of an inverted T-shaped cross-section and wall hangers of an L-shaped cross-section. A first, upright one of the components has a generally rectangular cross-section with one longitudinal edge recessed. The second component has a central groove for receiving the first component. The sides of the groove are stepped to give two steps which complement the recess edge of the first component. The first component can be fitted with its plain edge in the central groove to form an inverted T-section; with its recessed edge engaging one step to form an L-section, and with its recessed edge engaging the other step to form a J-section. The system may conveniently be sold in kit form comprising the two components and, possibly, joining members for joining cross beams to main beams.

Abstract: Problems encountered in adapting child restraint devices of the kind used to retain a child in the seat of a shopping cart, "stroller", dining chair, or like device, for use in different circumstances and with children of different sizes, are overcome by a restraining device which comprises a pair of straps, each having a releasable fastener at each end portion. The cooperating parts of the fastener are spaced apart lengthways so that when they are fastened the end portion will form a loop. In use, the straps are placed over a child's shoulders and crossed over each other both front and rear. The ends of the straps are attached to a belt secured around the child by looping the end portions around the belt and fastening the releasable fasteners. The restraining device conveniently restrains the child in the seat, the shoulder straps preventing it from wriggling upwards out of the waist belt. Because the straps are releasably attached to the belt, they can be used independently.

Abstract: Network terminating terminal apparatus, for use in an Integrated Services Digital Network, comprises a U-interface and a S/T interface. The U-interface allows the integrated terminal apparatus to communicate with a central office directly, without a separate network terminator. Remote terminals may be connected to the network terminating terminal apparatus, via its S/T interface. The network terminating terminal apparatus then serves as a conventional network terminator. The network terminating terminal apparatus includes circuitry for controlling D-channel access by the integrated terminal apparatus. The circuitry detects the framing of the signal received at the U-interface and the D-channel information from the remote terminals and ensures that the D-channel data from the integrated terminal apparatus is supplied to the S/T interface at the appropriate time for insertion into the D-echo channel of the signal returned to the remote terminals.

Abstract: In apparatus, such as a weapon sight, the speed of an object moving relative to a scene is determined by processing a plurality of successive frames of data, each obtained by scanning the scene, and detecting motion of the object relative to the background/foreground features of the scene. Each frame is compared with a reference comprising a different one of the frames and corresponding background features registered. Once the frames are registered, light intensity values of corresponding elements of the frames are subtracted. The registered background features, being stationary, cancel leaving the object features. Displacement of the object features over a predetermined number of frames is used to calculate the crossing speed of the object relative to the background features.

Abstract: In a magnetic compass of the kind in which a sensor derives coordinates of a sensed magnetic field, automatic correction of hard-iron and soft-iron distortions is achieved by storing a set of measured values of the magnitude of the sensed magnetic field for different discrete directions of the alignment axis of the compass relative to an estimated origin. If measured values have been accumulated for more than a predetermined number, but not all, possible directions, values are interpolated for the remaining directions to provide a set of measured and interpolated values defining a substantially elliptical locus of the sensed magnetic field vector (E.sub.T.) New coordinates for the estimated origin are derived and the measured values adjusted to take account of changes in the estimated origin. The heading is corrected for displacement of the origin due to hard-iron effect and for ellipticity of the locus due to soft-iron effects.

Abstract: An optical interconnection device suitable for an N.times.N' coupler as used, for example, in a local area network, comprises diffraction means in the form of a body having a refractive index which varies spatially and periodically in one plane of the body. The arrangement is such that light incident upon the body in the plane and at a predetermined angle will be refracted to emerge at a plurality of discrete angles determined by the spatially varying refractive index. The incident light is distributed substantially equally among the plurality of output refracted beams and substantially all of said incident light is coupled to the plurality of refracted beams. The diffraction means comprises a cylindrical body, and the device further comprises two arrays of optical sources and/or receivers. The arrays are disposed at opposite faces, respectively, of the body, each of the optical receivers having an optical axis aligned with one of the discrete angles.

Abstract: An integrated circuit having boundary-scan facilities in accordance with IEEE Standard 1149.1, has its boundary scan chain configured to permit fault insertion testing of diagnostic and maintenance software. Each Scan cell includes storage devices for storing a pair of bits of a binary vector shifted into the boundary scan chain. One bit comprises faulty data and the other bit serves to control application of the faulty data by the scan cell. A system incorporating such integrated circuits includes a controller for controlling the IEEE test interface to shift the binary vector into the boundary scan chain, and diagnostic and maintenance software for diagnosing the faults introduced into the integrated circuits.

Abstract: A telephone set which may be readily changed from a desk unit to a wall mounted unit without tools and without removing and re-installing any receiver-retaining parts or components has a handset with a receiver portion and a transmitter portion and a base with a transmitter portion receiving depression and a receiver portion receiving depression. An arm unit mounts within the receiver portion receiving depression. The arm unit has a pair of spaced apart side arms joined at one end by a transverse member. The arm unit has a pivotal mounting arrangement that enables the arm unit to move between a first position and a second position. In the first position, the set is used as a desk unit with the side arms at the sides of the receiver portion receiving depression and the transverse member is at the end of the receiver portion receiving depression nearer the transmitter portion receiving depression. In the second position the set is used as a wall unit with the side arms extending outwardly from the base.

Abstract: In apparatus for receiving digital data signals in a digital communication system, especially an Integrated Services Digital Network, timing recovery problems associated with erratic zero crossing when multiple terminals transmit to a common receiver are mitigated by detecting the rate of change of the digital data signal between two predetermined positions and controlling sampling of the digital data signal in dependence upon the difference between such rate of change and a reference. The rate of change conveniently corresponds to the trailing "corner" of a framing pulse, i.e. the point at which the signal commences the transition from one polarity to the other. The "corner" is much more stable, i.e. less susceptible to variation due to multiple terminal effects, than the zero-crossing which follows it, since the zero crossing may vary relative to the "corner".

Abstract: A warning device for incorporation in the handle-bar of a bicycle has a casing with a tubular portion and a head portion. The tubular portion fits inside the end of the handle-bar while the head portion abuts the end of the handle-bar. A flat spring member with an arc-like configuration extends longitudinally outside the tubular portion to engage the inside of the handle-bar and retain the casing in its installed position. There is a battery cell within the tubular portion as well as circuitry. A piezoelectric transducer mounted inside the head portion is connected to the circuitry to form an oscillatory circuit. A switch is mounted externally of the head portion, preferably extending back over the end of the handle-bar. One side of the switch is connected through the spring member to one side of the cell and the other side of the switch is connected to the oscillatory circuit. Closing of the switch supplies power to the oscillatory circuit causing the transducer to generate a warning sound.

Abstract: An anti-jackknifing coupling device, for an articulated veicle such as a tractor-trailer combination, comprising a base member for mounting upon the tractor. A turntable member is rotatably mounted upon the base member, and a trailer support member is supported upon, and rotatable with, the turntable. The trailer support member, usually called a "fifth wheel", serves to releasably couple the trailer. A piston-and-cylinder device is connected at its one end to the turntable and at its other end to the base member, so taht it extends substantially diametrically across the turntable member when the vehicle is straight. As the tractor and trailer pivot, the trailer support member and turntable rotate together relative to the base member, causin contraction of the piston-and-cylinder device. The trailer support member will usually be able to tilt relative to the turntable about a lateral pivot axis.

Abstract: In the class of electronic circuits known as current conveyors, limitations in the areas of frequency bandwidth, transient response, output impedance, distortion, accuracy, and suitability for integration are overcome by means of a current conveyor comprising a Wilson current mirror of one polarity type cross-coupled with a second Wilson current mirror of the opposite polarity type. The first Wilson current mirror is connected to an input port and a reference port. The second Wilson current mirror is supplied with current by a current-splitting circuit which also supplies an output port with a currrent that is proportional to, preferably half, the current supplied to the second current mirror. An emitter de-generation compensation scheme may optimize the transient response and stability of the mirrors. The current splitter may also comprise current mirrors. A voltage-to-current converter may be realised by connecting suitable resistors in series with the input and reference ports, respectively.

Abstract: An automatic optical inspection system, for inspecting printed circuit boards and the like, employs so-called dimensional verification and pattern recognition techniques simultaneously. The printed circuit board is scanned by means of a CCD camera to produce a binarized image of the board. The image is stored and access provided to a set of picture elements arranged in a generally circular configuration and which are spaced apart by a dimension to be monitored by dimensional verification (DV) means. Access is also provided to a second set of picture elements arranged in a generally rectangular array of picture elements for the pattern recognition (PR) means, which uses template matching to determine their validity. The DV and PR outputs are weighted and clustered before a fault is signalled.

Abstract: A video codec is used to reduce the bandwidth of a video signal for storage and/or transmission. To transmit an uncoded quality color NTSC television signal is digitized form requires channel bandwidth typically 90-120 Mb/s for the signal in the composite format and 216 Mb/s for the signal in the component format. The proposed video codec achieves a reduction of the required transmission bandwidth by a factor of 2-3 by splitting the imput signal into two channels, a main and a complementary channel, and by applying different coding techniques in each. In the main channel the input signal is subsampled and DPCM encoded using a fixed-rate companded quantization, whereas VWL and block coding is used to encode the complementary channel carrying the interpolation error signal. This arrangement seeks to ensure high picture quality while being easily adaptable to different transmission rates and signal formats.

Abstract: An adaptive hybrid arrangement for interfacing a bidirectional communications channel with two unidirectional channels, especially for connecting a two-wire telephone line to a four-wire telephone trunk or repeater, comprises a hybrid having four ports. One port is for the two-wire or bidirectional channel, the second and third are for the unidirectional channels. A multi-element balancing network is connected to the fourth port, i.e. opposite to the port connected to the bidirectional channel. Correlation detection means detects correlation between a signal in one of the unidirectional channels and an error signal in the other. If correlation exists, adjusting means adjusts the balancing network so as to reduce such correlation.

Abstract: A microphone arrangement, suitable for a telephone handset, comprises an array of microphone transducers, conveniently pressure transducers arranged at the vertices of a cube. Signal processing circuitry derives from the transducer outputs signals representing the magnitude and direction of the pressure gradient of the sound field at the array. In response to these signals, the microphone transducer outputs are weighted so as to direct the directional sensitivity lobe of the microphone towards the source of the maximum sound detected thereby.

Abstract: A crossover arrangement for optical conductors, each in the form of a rod of light-transmissive material, includes a multifaceted, e.g. polyhedral member having pairs of mutually parallel opposed facets. Each pair of facets extend in a direction transverse, preferably perpendicular, to that in which a second pair of facets extend. The end face of each optical conductor is abutted against one of the facets of the polyhedron. Each facet has a coating of a material having a lower refractive index than that of the polyhedron or the optical conductors. Light entering the polyhedron from one conductor passes across the polyhedron and into the opposite conductor, being constrained to stay within the polyhedron by the coatings on the side facets. Preferably the polyhedron member is a cube and the optical conductors are of square cross-sectional shape.

Abstract: A mounting arrangement for mounting an optical conductor on a "photonic" backplane provides for simple, accurate positioning during installation and easy access to, and removal of, the optical conductor when in service. The optical conductor constitutes a "busbar" in that it has a series of reflector surfaces spaced along its length to permit distribution or aggregation of several light signals. In one embodiment, an individual support is provided at each reflector/circuit card location. Each support is a seating member which houses a lens to couple light between the optical conductor and the circuit card. In another, preferred, embodiment the optical conductor is housed in a channel in a guide rail mounted upon the backplane. Separate cover members are releasably mounted upon the guide rail adjacent each circuit card. Each cover member has an aperture and lens to couple light between the reflector and the circuit card.