Abstract: A weapon system including a primary weapon arranged to be guided to a target, and further comprising at least one secondary weapon forming a unit with the primary weapon, but being releasable from the primary weapon on the approach to a target, the secondary weapon or weapons being controllable, on release, to ensure target destruction should the primary weapon not succeed in target destruction.

Abstract: A flextensional sonar transducer comprising a first cavity defined by an elliptical shell and end plates covering the two ends of the shell, vibration drive means inside the cavity and coupled between portions of the shell wall at opposite ends of the major axis of the shell, a further cavity connected to the first cavity and an opening between the two cavities for coupling the two cavities for the further cavity to affect the resonant frequency of the first.

Abstract: A method of processing video image data for use in the storage or transmission of moving digital video images, includes decomposition of each frame image into an equivalent set of sub-images containing information on different length scales, derivation of encoded prediction rules from the decomposed data to approximate each sub-image using data from the immediately preceding compressed sub-image and data from the current sub-image to produce compressed data of an image for subsequent storage or transmission to a receiver and reconstruction, after retrieval or receipt, by comparison of the compressed data received for the current frame image with the reconstruction of the preceding frame image.

Abstract: An asynchronous communications device includes a dual port memory, means for inputting data into the dual port memory, and means for outputting data from the dual port memory, the device being configured to operate in a receive mode or a transmit mode according to its connection in a communications system. Suitably the device includes a built-in test facility for both the transmit mode and the receive mode. Preferably a clock frequency of 80 MHz is used for the operation of the device, and a 40 MHz clock signal is used to derive the 80 MHz clock frequency, the 80 MHz frequency being formed by four 20 MHz clock frequencies arranged with their rising edges 90.degree. out of phase. There is also provided a method of producing a clock frequency by utilizing four clock pulses with their rising edges 90.degree. apart.

Abstract: A signal processing system for collecting and outputting samples of a signal; in which the system has a memory into which the samples are written such that when the memory is read the samples are read sequentially and always in the same frequency order, irrespective of the arrival sequence of the different frequencies.

Abstract: An arrangement for suppressing aerodynamic noise generated by cavity effect interaction between a wing flap shroud and one or more partially deployed trailing edge flaps. Noise suppression vanes are so positioned with respect to the shroud lower trailing edge and the leading edge of the wing flaps at partial deployment that eddies and vortices resulting from airflow separation at the shroud lower surface are diverted sufficiently by the noise suppression vanes to avoid significant noise inducing impingement of the separated flow on the flap leading edge.

Abstract: A synthetic aperture radar assembly (1) locatable on a satellite (2) for radar imaging of a planet surface (3) in swaths, including means (8) for transmitting pulses (4) of electromagnetic radiation towards the planet surface (3) to be imaged, means (8) for receiving echoes of said pulses (4) returned by said planet surface (3), means for creating an image of a swath (5) of said planet surface (3) from said returned echoes and means for randomly varying the frequency of transmission of said pulses (4) to increase the width (11) of swath (5) imagable.

Abstract: An aircraft includes a nozzle assembly 18, 20 for exhausting efflux from the powerplant. Each nozzle assembly may be moved from a stowed position in which it is flush with the surrounding surface of the aircraft to an operative position in which it projects therefrom to exhaust efflux.

Abstract: The invention relates to detecting distortion in large engineering structures using one or more fibre optic cables bonded to or in the structure. An optical signal is transmitted along the cable and information is obtained from the received signal regarding the length and/or change in length of the cable.

Abstract: An aerodynamic or hydrodynamic surface having a swept-back leading edge includes at least one flow separation device located on an attachment line of the leading edge, such as a step-up, step-down, fence or gap. The flow separation devices are preferably arranged normal to the leading edge and are dimensioned so that span-wise turbulent air flow is re-laminarized downstream of the devices thus reducing skin-friction and greatly improving the aerodynamic or hydrodynamic efficiency of the surface.

Abstract: An Earth orbiting spacecraft (1) is returned to an Earth pointing attitude by means of a star sensor (6), Earth sensor (2), Sun sensor (4) and an angular momentum storage device. With the Sun sensor (4) locked on the Sun (5) the spacecraft is rotated until the star sensor (6) senses a predetermined brighter than magnitude 3 star such as Canopus (7). The angular momentum storage device is operated to preserve an attitude reference and the spacecraft (1) is further rotated by an angle .alpha. such that subsequent rotation around the angular momentum storage axis causes the Earth (3) to enter the view of the Earth sensor (2).

Abstract: A signal repeater assembly (1) for a spacecraft, includes a channel selectivity network (CSN) (2) having a plurality of first input ports (4-13) connected by selectively operable filter circuits (14-23) to a plurality of first output ports (24-31) to enable a signal at any selected first input port (4-13) to be passed to any selected first output port (24-31). The CSN (2) is connected to a shared power amplification module (SPAM) (3) having a plurality of second input ports (44-51) for receiving signals from the first output ports (24-31), a plurality of second output ports (52-59) and a network (60) of balanced amplifier devices (61) operable to couple the second input ports (44-51) to the second output ports (52-59) so that any amplification of a signal received at any one of the second input ports (44-51) is shared by all the amplifier devices (61) to allow the total available amplification power to be used by any one or a combination of second output ports (52-59).

Abstract: A process and apparatus are provided for controlling the alignment of a transmit laser beam (1a) of a first coherent detection optical communications transmitter/receiver terminal with a further coherent detection optical communications transmitter/receiver terminal relative to a receive laser beam (8). The first terminal incorporates a transmit laser beam generator (1) operable to form and pass the transmit beam (1a) through a point ahead mechanism (2) to a telescope assembly (6) operable to receive the receive laser beam (8).

Abstract: The invention relates to engine air intakes for aerospace vehicles in which a variable geometry ramp system is employed for matching air intake flow to propulsion engine demand. To alleviate the induced high pressure loads on the ramps and the ramp actuators arising from the air intake flow a reacting pressure is applied to the opposite face of the ramps. The ramp assembly in addition to defining the required air intake duct geometry further defines the adjacent boundary of an enclosure which is pressurized by ram air and vented as required as a function of the load on one of the ramp actuating jacks to give the desired load alleviation.

Abstract: Contact lenses can be made by machining an inner concave surface into a plastics material blank, then mounting the blank in a lathe and machining the outer convex surface thereon. Repeated measurement with a micrometer is needed during the latter machining to ensure that the lens vertex is correctly formed. To avoid this, the sensor described herein comprises a remote laser source from which radiaiton passes the lens vertex in the blank to a detector, the items being arranged so that, when the lens has been correctly machined, a surface diffraction effect occurs at the vertex leading to a detectable signal from the detector. The basis of the technique is the projection of an image of an edge diffraction intensity distribution through a slit to the detector while the non-diffracted component of the laser beam is prevented from reaching the detector.

Abstract: This invention relates to a method and apparatus, i.e. a "wavelength meter", for determininhg the wavelength of optical radiation, e.g., visible radiation. Radiation is subjected to two or more wavelength dependent phase modulations having a net effect which is wavelength dependent and is zero at a predetermined wavelength. The net modulation is then determined so as to obtain the difference between the predetermined wavelength and the actual wavelength of the radiation.

Abstract: A device for making adjustments to the label values of objects within an image being processed. The device, which receives a train of digital signals, identifies signal values within the train which are to be modified, and makes the appropriate modifications. The device comprises a multiple-route shift register arrangement which receives the train of signals and compares these values of each with a series of `to be corrected` values and, on detection of correspondence, replaces them with `correction` values in a third series.

Abstract: A system for controlling the frequency of one of the CW and CCW beams in a ring resonator gyroscope in which the relative intensities of the second harmonic of the path length control signal in the CW and CCW beam are used to generate a control signal to null the gain differences between the photodetectors and pre-amplifiers in the CW and CCW channels. The scheme allows a greater degree of common mode rejection than known systems.

Abstract: Disclosed is a roll rate sensor which may form part of a roll position sensor (an "up-sensor") and which comprises a vibratory element rotated by a motor within a projectile body so its rotation speed about the projectile axis is the sum of the motor speed and the projectile roll rate. The resultant centrifugal force acts on the element so as to vary its effective stiffness and hence its vibration frequency. A transducer is arranged to provide a signal corresponding to the vibration and hence to the centrifugal force and the roll rate. The vibratory element may comprise a metallic or silicon beam element.

Abstract: Apparatus for launching a projectile which has a nozzle for emitting gas during launch, said apparatus comprising means for supporting a projectile and a chamber having an orifice positioned to receive some or all of a jet from the projectile nozzle wherein the chamber is configured so that pressure is developed therein to provide an additional boost to the projectile during launch.