Abstract: A method of blind signal separation of convolutively mixed signals comprises firstly processing signals to produce second order independence. In a second step, and together with ranges of signal delay and rotation parameters, the resulting processed signals are used to determine delay and rotation parameters. These parameters implement at least one elementary paraunitary matrix and transform the processed signals into output signals with improvement in independence to at least a predominant part of a maximum extent obtainable over the parameter ranges. The output signals then become the next processed signals and the second step is iterated until independence ceases to be improved significantly. The latest output signals are then unmixed signals.

Abstract: A drive configuration for a skid steered vehicle comprises a pair of electric motors for propulsion of the vehicle, one each coupled to drive a respective track on a respective side of the vehicle, and one or more electric steer motors coupled through a differential gear mechanism to impose a speed difference between the tracks. An associated control system controls the current to each motor so that substantial contributions to the differential torque to turn the vehicle are made both by the steer motors and by the propulsion motors, in variable proportions preferably as a function of the vehicle speed.

Abstract: A semiconductor device comprising a plurality of regions of semiconductor material forming a junction at an interface there-between, the junction including a depletion region having a width which varies spatially in at least one direction along the depletion region. Without limitation, the spatial variation in depletion region width is provided by ionised dopants having a concentration which varies spatially along said at least one direction. Alternatively, or in addition, the spatial variation in depletion region width is achieved by varying the thickness of the region(s) of semiconductor spatially along said at least one direction, for example by creating a plurality of cells within said region(s) devoid of said semiconductor material. A method of fabricating a semiconductor device comprising the step of varying the width of the depletion region spatially there-within in at least one direction along the depletion region.

Abstract: An eddy current sensor for use as a dynamic proximity sensor, particularly for monitoring of blade tip timing and clearance in turbomachinery, has a common coil for use in both generating a magnetic field in a proximate region and detecting the effect of eddy currents generated by said field in electrically conductive objects passing through that region. The coil is wound on a rectangular or other elongate former so that the coil is itself elongate in section. This can improve the resolution of the device when used for sensing the passage of objects of elongate section (such as a turbine blade tip when the sensor coil is oriented with its shorter cross-sectional dimension aligned with the shorter cross-sectional dimension of the respective object. Also described is a method of processing a signal wave form from such devices to derive ‘trigger’ points for blade tip timing.

Abstract: A self opening hinge comprises a tubular member with a set of circumferentially spaced blades extending longitudinally between opposite end portions. It can be folded by bending the blades to bring the end portions together and when released will naturally return to the straight condition under the spring action of the blades. The blade which will be located on the inside of the fold when the member is in its folded condition is configured with a convex circumferential curvature as viewed from the axis of the member when in its unfolded condition, namely reversed in curvature as compared with the other blades. In this way the stress on the inside blade when the member is folded is reduced as compared with a conventional hinge where all the blades follow a circular tube profile and are concave as viewed from the central axis.

Abstract: A method for providing correction values for phase based measurements. Where averaging techniques are employed for exploiting redundancy in multiple measurements, by constraining the phase ambiguity in a correction value to be an integer multiple of the carrier wavelength, carrier phase based measurements can be used.

Abstract: A substrate including a surface on which is provided a modifying layer which is incomplete and has a distribution such as to provide a plurality of islands of said material and/or islands of substrate surface whereby the surface exhibits a modified electrical and/or magnetic property.

Abstract: Integration of ionospheric models in over the horizon radars (OTHR) is achieved with very little or substantially no change to existing coordinate registration systems or software by specifying a virtual transponder at a target location and generating a signal which appears to have emanated from a transponder at that location. A return path to said virtual transponder is ray-traced through the ionospheric model to produce propagation parameters; and an appropriately delayed virtual transponder signal is inserted into the receiver. The result produced at the receiver is used to perform coordinate registration for further received signals.

Abstract: A polarimetric imaging apparatus (2) and method for distinguishing objects of interest within a scene, said apparatus comprising means for resolving electromagnetic radiation received from the scene having a first substantially circular polarisation state into a first image and for resolving electromagnetic radiation received from the scene having a substantially circular polarisation state of opposite handedness to that of the first circular polarisation state into a second image so as to identify differences there-between, and means for providing an output indicative of the difference there-between, wherein the resolving means is arranged in use to resolve said electromagnetic radiation into said first and second images successively.

Abstract: A vehicle arresting device comprises a net intended to be laid flat on the ground in the path of a target vehicle with an array of upwardly-directed spikes attached to the net along a leading portion, so that when a vehicle runs over the device some of the spikes engage in its front tires and the net is caused to wrap around the front wheels, being pulled tight under the vehicle to prevent further rotation of those wheels. There are two rows of spikes, with the spikes in the second row being substantially longer than the spikes in the leading row. The gauge of the netting also varies, with the leading strip which includes the shorter spikes and back towards the longer spikes being of a thinner gauge, the portion from the longer spikes back to approximately the mid length of the net being of a thicker gauge, and the trailing portion reverting to the thinner gauge. These measures help to ensure that the net is capable of arresting a wide range of vehicles, from passenger cars to trucks.

Abstract: A time delay beamformer comprises input channels, which have associated samplers arranged to sample inputs signal carried upon the input channels. The samplers sample the input channels at a number of points in time to produce a number of sampled signals. An adaptive processor receives each of the input signals and each of the sampled signals, and generates processed signals therefrom. Time delay devices introduce a steering time delay to the processed signals and a summer generates a beamformed output signal the delayed processed signals.

Abstract: A strain-responsive visual indicator comprises a pair of overlapping shutter strips (1, 2) adapted to be mounted to a substrate such that strain in the substrate causes relative movement M between them. Each shutter strip comprises an alternating set of windows (5) or (6) and bars (7) or (8) and the distal strip (2) is backed by a strip (3) of a different color exposed through its windows (6), or the distal strip can instead be printed with a set of alternating colors in place of its windows and bars. The effect is that under different strain conditions different color indications from the distal strip (2) will be visible through the windows (5) of the proximal strip (1), in accordance with the relative positions of the two strips. The indicator can be incorporated e.g. in the shaft of a toothbrush to give a visual warning in response to flexure of the shaft if excessive brushing pressure is applied. Numerous other applications and the use of different types of indicia are indicated in the specification.

Abstract: A multicore optical fibre includes a microstructured cladding material formed from a plurality of cladding elements arranged in an array and each cladding element comprising at least two different materials each having different refractive indices, and a plurality of core elements formed within interstitial regions between adjacent cladding elements. A fibre so formed may have a large number of cores per unit cross-sectional area as compared with prior art fibres, and thus allows the fibre to have relatively short distances between adjacent cores for a given required inter-core isolation. A fibre so formed has utility in many areas requiring high core density, such as inter-chip optical communication, or optical communication between circuit boards.

Abstract: A multicore optical fibre includes a microstructured cladding material formed from a plurality of cladding elements arranged in an array and each cladding element comprising at least two different materials each having different refractive indices, and a plurality of core elements formed within interstitial regions between adjacent cladding elements. A fibre so formed may have a large number of cores per unit cross-sectional area as compared with prior art fibres, and thus allows the fibre to have relatively short distances between adjacent cores for a given required inter-core isolation. A fibre so formed has utility in many areas requiring high core density, such as inter-chip optical communication, or optical communication between circuit boards.

Abstract: In order to check the authenticity of a banknote or other such document it is printed with two patches of magnetisable ink, and each patch is magnetised to present a multipole sequence of alternating polarity. If the document is folded to bring the two patches together and then rubbed to and fro in the direction of the pole sequences, they will be subject to alternating forces of attraction and repulsion which can be sensed through the fingertips and gives the impression of a physically rippled texture notwithstanding that the patches actually have a smooth surface. The presence or absence of this effect can therefore be used to distinguish between a genuine document bearing such magnetised patches and a counterfeit which may be visually identical but lacks the correct magnetisation. In a variant only one of the patches is printed on the document itself and the other is on a separate “key” device which is rubbed over it to test for the presence of the correct magnetisation.

Abstract: A controlled differential, particularly for exercising steering control of skid steered vehicles, having a compound planetary gear set coupling two shafts. Respective ring gears turn with the shafts and mesh with a compound planet gear in a planet carrier, the ratios of the number of gear teeth between each ring gear and the respective gear of the compound planet being unequal so that when the planet carrier is stationary the two shafts are coupled through the differential to turn together in the same sense but with a speed difference, and controlled rotation of the planet carrier varies the speed difference between the shafts in accordance with the sense and speed of rotation of the planet carrier.

Abstract: A signal generation system suitable for use in a radar system comprises a local oscillator (LO) and an intermediate frequency (IF) oscillator, wherein the IF oscillator is a Direct Digital Synthesiser (DDS), and the LO is a free running oscillator not itself locked to another oscillator but which acts as a clock reference for the DDS and is the highest frequency oscillator in the system. The LO may also act as a reference for a receive chain digitiser. The invention exploits phase noise advantages of a free running oscillator at some distance from the carrier whilst maintaining coherency with other system components. The system typically finds application in FMCW radars.

Abstract: Disclosed is a modular bridge, typically for temporary use to enable persons to pass between upper floors of adjacent buildings during fire fighting or disaster relief operations, which can be rapidly assembled and deployed within a confined space and entirely from the “home” side of the gap to be crossed. It comprises a plurality of man-portable box section bridge modules adapted to be connected together end to end and projected in cantilever fashion from one side of the gap to the other. The assembly of modules is supported in and guided through a launch frame, with modules being added to the rear of the assembly and pushed through the frame until the gap is spanned. Removable lever arms of the frame are used to counterbalance the weight of the projected bridge modules during the course of deployment.

Abstract: A reflector assembly for use with a paraboidal reflector comprises a generally-cylindrical body (302) having a plurality of stepped facets (306) extending circumferentially around its internal surface. Each facet serves to reflect divergent light from a light source (308) back onto the primary reflector (314) for re-reflection thereby enhancing the beam produced. Such a reflector can be used with existing lamps or alternatively a purpose built composite reflector incorporating such an element can be designed.