Abstract: An engine nozzle arrangement for an aircraft comprises a nozzle (18) for hot exhaust gases, and a shroud (20) for the stream of hot exhaust gases emerging from the exhaust nozzle. The shroud includes an intake for a boundary layer of air for cooling the stream of exhaust gases.

Abstract: Two-photon absorption measurements are made at various points remote from monitoring apparatus by apparatus which includes two lasers that produce counter-propagating beams through the earth's atmosphere. The lasers are tuned such that the sum of the energies of the photons in each of the laser beams equals that associated with a predetermined transition of a gas in the earth's atmosphere. In one embodiment, a pulsed laser and a CW laser are used. The pulse from the pulsed laser propagates along the CW beam produced by the CW laser and overlaps the CW beam at positions determined by a range gating technique, which makes possible the measurement of the two photon absorption at the various positions of overlap or coincidence. In one embodiment, the subject apparatus is utilized for pollution monitoring, in which the frequencies of the lasers are tuned such that the energies of the photons from these lasers add up to a transition of a predetermined pollutant.

Abstract: An optical target (1) including a positioning sub target (2) for determining position, and a plurality of identifying sub targets (3) for identifying one optical target (1) from another, each of which plurality of identifying sub targets (3) is a different color from the positioning sub target (2).

Abstract: A head tracker system for determining a user's head orientation relative to a datum comprises: a head mounting, preferably a helmet (2), for attachment to the user's head and a sensor system (10,12) for sensing the orientation of the head mounting (2) relative and the datum. A distinguishable marking (26) is provided at a first known point fixed relative to the head mounting or a second known point fixed relative to the datum. At the other known point an optical sensor (18), preferably a video camera, is mounted. The system further comprises processing means (28) for determining when the marking is within the field of view of the optical sensor and the output of the processing means is used to correct for drift in the sensor system or to provide an independent verification that the system is functioning within preselected tolerances.

Abstract: A method and apparatus are provided for determining whether a signal received the main channel (2) of an antenna (1) was incident on the antenna (1) in a direction corresponding to a high gain main lobe. A sidelobe suppression signal is generated from signals received from a other channels at least some of which are derived from elements where output generates the main channel, the signal being categorized as originating from a direction corresponding to the high gain main lobe of the main channel by comparing the value of the signal received on the main channel with that of sidelobe suppression signal.

Abstract: A microwave imaging excavator for the detection, imaging and excavation of objects on or buried beneath the surface of the ground, such as metallic and dielectric land mines. A continuous wave stepped frequency ground penetrating radar signal is transmitted into the ground from a waveguide antenna mounted in one spade of a double spade auger. Direct breakthrough energy, signals reflected from the surface and the buried objects are received by an identical waveguide antenna mounted in the opposite spade. The spectra reflected from different buried objects become more distinct when the spectrum radiated spans the natural electromagnetic resonance of those objects. These signals are recorded as the twin-spaded auger is mechanically scanned over the ground in two mechanical rotational states of polarization. When the auger spades are on either side of a buried mine they are closed to grasp the mine which is then removed from the ground.

Abstract: A method of manufacturing a composite laminate and a composite laminate manufactured according to the method are provided. The laminate comprises a series of fabric plies (1 to 15) of fibrous reinforcing material set in plastics matrix material. The method includes the steps of providing a relatively small number of fabric styles from which to choose; selecting at least one of those fabric styles according to design requirements for a particular portion of the laminate; laying up that portion with the said selection, and repeating the selection and layup steps as required to complete the layup of the laminate.

Abstract: A motor controller includes: a driver stage operable to provide voltage and current to a plurality of induction motors over a single power bus; and a control unit operable to monitor the current drawn from the driver stage and cause one or more of the induction motors to operate in a regenerative mode to supply current to at least one other of the induction motors when the current drawn from the driver stage exceeds a threshold.

Abstract: The present invention features an improved cross-element meander line loaded antenna. Two pairs of triangle-shaped elements are each connected at their vertices to form bow-tie elements. The bow-tie elements are arranged orthogonally adjacent a ground plane, reducing shadowing and cross-coupling, and providing an efficient and compact meander lines antenna. When fed in quadrature, the antenna radiates a circularly polarized RF field having an excellent axial ratio.

Abstract: The present invention provides a reconfigurable diplexer which is well suited for use with mulitple element antenna arrays. The diplexer includes a common, slot-line transmission line adapted to carry electromagnetic signals; a pair a separate slot-line transmission lines coupled to the common transmission line; each separate slot-line transmission line having an individual filter coupled thereto, wherein each filter is adapted to selectively give its respective separate slot-line transmission line a characteristic impedance dependent upon predetermined frequencies of the electromagnetic signals; and a separate slot-line balun associated with each separate slot-line transmission line and adapted for coupling signals to and/or from its respective separate slot-line transmission line. The diplexer may be configured to operate in several different bands such as the INTELSAT frequencies (7.2-8.4 GHz) or DSCS frequencies (11.7-14.5 GHz).

Abstract: A meander line loaded antenna (MLA) that utilizes more two or more layers of meander lines to greatly extend the operating frequency range. The antenna of the present invention can achieve an operating frequency range of 100:1, unlike antennas of the prior art, which were limited to frequency ranges of approximately 10:1.

Abstract: The present invention relates to a system for sweeping a laser beam in a preset pattern, while, at the same time, directing the pattern to any area in a predetermined scanning area. The invention is particularly useful in LADAR applications. In one version of the invention, a series of optical prisms are arranged in concentric tubes so that the prisms have a common optical path. The tubes and, hence, the prisms, may be independently rotated by precision electric motors coupled to gear rings on the tubes.

Abstract: A multiple spectral band opto-mechanical modulator for obtaining simultaneous but independent modulation of an extended IR source in two distinct wavelength bands comprises in one embodiment a first rotating filter wheel having alternating radial segments of transparent and short wavepass filter material, a second rotating filter wheel having alternating radial segments of transparent and long wavepass filter material, a stationary wheel having alternating radial transparent and opaque segments positioned intermediate the first and second rotating wheels and means for rotating said first and second filter wheels at predetermined frequencies.

Abstract: The present invention provides a single-event upset (SEU) hardened integrated circuit. The integrated circuit includes an SEU hardened asymmetric bi-stable CMOS latch having a first logic state and a second logic state. A supply voltage is operably coupled to the asymmetric bi-stable latch, where upon activation of the supply voltage the asymmetric bi-stable latch is always set to the first logic state. A switch may be provided for changing the latch from the first logic state to the second logic state.

Abstract: A display arrangement particularly suitable for replacing a conventional CRT in a pilot's helmet mounted display includes a light source having a modulated output which is scanned by a scanner across a screen to produce an image. The image is transferred into the pilot's field of view by relay optics. The scanner and screen are mounted on the pilot's helmet and the light source is remote therefrom.

Abstract: An adjustable size annular retaining assembly includes at least two substantially rigid segments (1, 2) and means (3, 4) for pivotably interconnecting the segments in end to end relationship, so that when the segments are pivotally interconnected at all but a single pair of adjoining segment ends (1b, 2b), the assembly can be contracted to a reduced size condition (5) for insertion through or into or removal through or from a confined space (6), and expanded into a desired annular size condition (7) for pivotal interconnection of said non-connected pair of adjoining segment ends (1b and 2b).

Abstract: Apparatus for estimating a first height (1) of a vehicle (2) above a first reference surface (3), including a system (4) for determining position, velocity and attitude incorporating at least one sensing means (4b) operable to provide an output signal (5) indicative of a vertical specific force of the vehicle, error-estimating means (6) for receiving as input signals a horizontal reference velocity and position (4a) of the vehicle (2), and a radar altimeter measurement (7) of a second height (1b) of the vehicle (2) above a second reference surface (8) and for providing as an output signal (9) estimates of errors associated with the sensing means output signal (5), and integrating means (10) for receiving said sensing means and error-estimating means output signals (5, 9), and for subtracting the estimates of errors from the signal (5) indicative of vertical specific force while performing a double integration of the results of the subtraction, to provide an output indicative of the required estimated first he

Abstract: Terrain navigation apparatus (1) for a legged animal (2) traversing terrain (3) including a first system (4) for determining position, velocity and heading of the legged animal incorporating sensing means for sensing inertial motion in six degrees of freedom operable to provide signals indicative of a first velocity (5a), a first heading (7a) and a first position (9a) of the legged animal (2), contact means (11) for establishing, in a velocity profile describing motion of either foot of the legged animal, a period where the velocity should be zero (17), which period corresponds to full or partial contact of the respective foot (13a, 13b) with surrounding terrain (3), and error-estimating means (15) for receiving as input signals the velocity profile during the period and for providing as output signals estimates of errors (19) associated with the sensing means output signals, which errors operatively interact with the output signals of the first system to effect terrain navigation of the legged animal (2).

Abstract: A compressive receiver including a dispersive delay line (10) and a frequency translator (16, 18) is preceded by signal compressors (22a-d) that record the incoming signals at one speed and play them back at a higher speed. This increases the frequency spread and provides greater frequency resolution at the output of the receiver.

Abstract: A vehicle includes an arrangement, such as an internal-combustion engine coupled with a generator, for converting the energy in fuel into electrical form, while generating exhaust. An exhaust cleaning arrangement, such as a catalytic converter, preferably operating at a high temperature, cleanses the exhaust. During deceleration of the vehicle, excess electrical energy is used to heat the exhaust cleaning arrangement.