Abstract: A radar for a terminally-guided sub-munition is capable of differentiating between spatial depositions of target scatterers and clutter. The radar frequency f is swept, in stepwise manner, over a frequency range F, the frequency of 2N successive batches of M pulses being incremented in steps of f = F 2 ? N . To minimise variability of hybrid spectrum with relative target velocity, v, a duplexer transmits the 2 NM pulses with a monotonic frequency sequence derived from control circuit and the returns being reordered.

Abstract: A method of analysing clusters of bearings (A, B, C, D) taken of distant sources by an array of direction finding stations. Each bearing has an error +E and a triangulation process is used to fix the position of the sources. A combination of bearings is taken one each from the stations. Each bearing of the combination is taken in turn as a spoke (3) directed at a source. The triangulation process generates a bar (31, 32, 33) of intersection points along the spoke for each other bearing of the combination, each bar corresponding to the error +E of each bearing. The number of overlaps between pairs of bars along a spoke is totalled to give a spoke score. The spoke scores of all spokes of the combination is summed to form a fix confidence score for a source which may be associated with the combination, or cluster, of bearings. Methods are also provided for rejecting redundant fixes associated with subsets of bearings within a cluster.

Abstract: A channelised bearing processor comprises a channelised receiver consisting of a plurality of i.f. receivers (34 to 42) covering contiguous parts of a predetermined frequency range. Each of the receivers (34 to 42) is connected to a respective, continuously energised local oscillator (35 to 43). A plurality of direction finding antennas (10 to 15) are coupled to respective receiving channels for producing an amplitude signal. Each receiving channel includes a tunable i.f. receiver (24A to 24F) having an input (26A to 26F) for a local oscillator signal. A local oscillator selector (50) is responsive to an output from one of the channelised receivers (34 to 42) to connect the local oscillator (35 to 43) connected to that one of the channelised receivers (34 to 42) to the local oscillator signal inputs (26A to 26F) of the tunable i.f. receivers (24A to 24F) in the receiving channels.

Abstract: An apparatus for calculating the root square sum of a plurality of values includes a serial commutator for receiving input signals indicative of the values, serially coupled with a root mean square to direct current circuit for providing an output signal indicative of the root square sum of the values. The apparatus may include a plurality of magnetometers for measuring the total value of the magnetic field.

Abstract: A transport device consists of a drive roller and a follower roller. The medium to be transported, for example a card, is inserted between the two rollers. The follower roller is able to pivot on its mountings in order to bring the medium to a predetermined orientation by applying a tractive force to the medium.

Abstract: To provide stationary or mobile radar with the capability of measuring the true range profile, a radar system includes a voltage oscillator coupled to a duplexer via a pulse modulation circuit. A digital control circuit provides a sweeping 500 Mhz frequency (F) of 6N successive batches of pulses being incremented in steps of F/6N. Returns received in response to each transmitted pulse are then combined in a mixing circuit with the signal from the local oscillator to generate a signal IF; each signal is summed with signals for the same range cell derived from earlier pulses transmitted at the same frequency; thereafter the signals pass through a FFT circuit.To maintain the "dissected" spectrum centered at the 2N.sup.

Abstract: A thermal imaging device includes an array of pyroelectric infra-red detector pixels. An array of pillars carries electrical signals between each detector pixel and a respective signal processing circuit formed on a semiconducting substrate. Each circuit is connected to an individual display device carried by the substrate.

Abstract: A pyroelectric film has a pattern of interconnected electrodes formed on one major surface, and a pattern of discrete electrodes and electrically conductive patches formed on the other major surface. The film 21 is supported by pillars connected to the patches, the pillars also producing a path for electrical signals between the patches and a signal processing means. Each discrete electrode is connected to a respective patch by a respective strip of electrically conductive material.

Abstract: A thermal imaging device comprises a layer 11 of pyroelectric material, an array of interconnected electrodes 13, and an array of discrete electrodes 15 supported from a substrate 27 by pillars 23 of thermally insulating material. Heaters 17 and associated control electrodes 19 are also provided to reduce the temperature difference between the discrete electrodes 15 and the pillars 23 and substrate 27. Control circuits 25 are provided to control energisation of the heaters 17.In a preferred embodiment the heaters may be provided on the substrate 27 for heating the discrete electrodes 13, the control current to the heaters providing an indication of the temperature of the source of radiation.

Abstract: A projectile has a nose portion and a body portion. A plurality of winged, fin-stabilized flechettes are releasably mounted in the body portion. Each flechette is mounted with its longitudinal axis at a pre-set pitch to a longitudinal axis of the projectile. In use, with the projectile moving on a projectile trajectory, each released flechette follows a respective trajectory parallel to and at a predetermined distance from the projectile trajectory. The predetermined distance for each flechette is determined by its pre-set pitch to the longitudinal axis of the projectile.

Abstract: An absorber for radiation of frequency of the order of 1 THz is formed of a body of cured silicone-based elastomer containing an inert, powdered siliceous filler. Both the elastomer and the filler are electrically insulating and the surface of the absorber that is exposed to the radiation is preferably profiled to enhance absorption of the radiation. The profiling preferably takes the form of an array of sharp-pointed pyramids having rectangular or triangular bases. A method of moulding such absorbers is also disclosed.

Abstract: A pyroelectric film has a pattern of interconnected electrodes formed on one major surface, and a pattern of discrete electrodes and electrically conductive contacts formed on the other major surface. Each discrete electrode is connected to a respective contact by a respective strip of electrically conductive material. Regions of the film each including a contact and part of the associated strip are formed in tongues pulled out of the plane of the film. The contacts are thus able to make electrical contact with respective input terminals of an integrated circuit.

Abstract: An angular rate sensor comprises a pair of driven tines and a pair of output tines connected to the driven tines by a stem portion. A detection circuit including a set of output electrodes, associated with each output tines, generates a detection signal related to angular rate. A feedback circuit, including a further set of electrodes associated with each driven tine; utilizes a phase quadrature component of the detection signal so as to drive the driven tines towards a condition of torsional balance.

Abstract: An optical device for panoramic viewing comprising a housing provided with an entry window, a plurality of spaced receptive areas and a lens system for each receptive area so disposed that it lies between the entry window and the associated receptive area, the lenses within each said system being arranged so that an image of a respective sector of a panoramic scene is formed at each receptive area.

Abstract: A magnetic sensor arrangement for monitoring movement of a vehicle on a path includes a three-axis accelerometer (1) and a processing circuit (2) for evaluating the vector product Hp of magnetic field vectors measured by the accelerometer when the vehicle is at two successive positions on the path. The vector product is utilized to evaluate a parameter related to vehicle trajectory. The arrangement may be used to generate a firing signal in an explosive mine or for monitoring a flow of vehicles along the path.

Abstract: A transmitter station has a data source, a crypto unit, a buffer store for encrypted signals and a transmitter with an aerial, all with a common power supply. A switching control unit has a position in which it connects data source and crypto unit to the power supply but isolates transmitter therefrom, and another switch position in which transmitter is connected to the power supply while data source and crypto unit are isolated therefrom. In this way, if any signals output from data source pass directly (i.e. not via crypto unit) to the input of transmitter, they will not be sent on into the network because transmitter is "off" (i.e., de-energized) at that time.

Abstract: A microstrip antenna is formed of a 3.times.2 group of elements, with adjacent H-feeds. The outer pairs of elements are responsive to opposite senses of polarisation respectively and the inner pair of elements is responsive to both sense of polarisation. The appropriate phase for the respective element orientations are obtained by making S=r+.lambda./4 and q=p+.lambda./2 where .lambda. is the wavelength of radiation. The element spacing lies between 0.5.lambda. and 1.0.lambda., typically 0.85.lambda..Larger arrays are formed both by increasing the number of pairs of elements responsive to both senses of polarisation, but leaving the two outer pairs responsive only to respective opposite senses of polarisation, and by increasing the number of rows of pairs.

Abstract: An electrical apparatus for monitoring electrical continuity includes a number of input circuits each associated with a respective arm of a multi-phase rectifier circuit the continuity of which is to be monitored. Each input circuit includes a comparator which generates a train of pulses P while an input current persists in the arm. If a discontinuity arises in an arm for a first preset interval of time a monostable in that arm generates a first trigger signal. If the discontinuity persists for a further preset interval of time another monostable, common to all the arms, triggers an alarm via a bistable circuit.