Abstract: A pet door kit made of frame sides and door sides all of which may be assembled onto a mesh screen panel before the panel is required to be cut to allow for pivoting of the door. Advantageously each frame side is formed as an integral molding with an associated door side so that the skill of the installer is not required to locate the door within the frame. Economically, the two moldings thus provided are identical and securing members, i.e. pins are integrally provided to pass from one molding, through the mesh, and be force fitted into holes in the other molding. The assembly of the two moldings simultaneously and quickly assembles the door and frame onto the firm unsevered rigid support of the screen panel.

Abstract: An open transmission line system for locating an entity (110) moving along a defined pathway uses transmissions from a remote, independent transmitter (106), conveniently a commercial radio or television station. The system comprises two receivers, both tuned to the frequency of the transmission. One receiver (101) receives signals directly from the transmitter (106) by means of an antenna (104). The other receiver (102) receives the signal from the transmitter (106) by way of an open transmission line (107). A processor (103) processes the signals from the two receivers to detect the entity. The system may use transmissions at different frequencies from plural mutually-spaced transmitters (402; 403; 404) in order to provide reliability and to minimize the effects of multi-path signals. The system may employ a variable velocity open transmission line (507), comprising a central conductor means (1100) having a permeable central element (1202) carrying a helically wound conductor (1201).

Abstract: A dynamically controlled routing (DCR) telecommunications network is formed by a plurality of network switching elements, each connected to at least one other by at least one circuit group for carrying calls therebetween, and a network processor connected to the network elements by data links. Each network switching element determines, for each call, a neighboring network element to which it should be routed. It does so by accessing a routing table which contains alternate routes to be attempted if a direct route either does not exist or cannot be used. The routing tables are updated periodically by the network controller. The DCR network functions as a group of nodes interconnected by links and routing takes place on a node-to-node basis.

Abstract: In an intrusion detection system comprising an open transmission line (10), for example a "leaky cable", and a receiver unit (12S,12T,14S,14T,16) for processing a radio frequency signal received by the line to detect perturbations caused by an intruder (28), problems of nonlinear sensitivity due to line attenuation are resolved by combining perturbation signals (R.sub.S, R.sub.T) from both ends of the open transmission line. A processor unit (18) computes logarithmic values of the perturbation signals from the opposite ends of the line and combines them to detect presence of an intruder. The sum of the logarithmic values may be used to determine presence of the intruder and the difference between them may be used to determine the location of the intruder relative to the end of the line. The processor may also use phase information from the two perturbation signals to facilitate detection in the presence of multipath effects. Reference signals (LO,IF.sub.

Abstract: A fishhook device comprises a hook unit and a lure member releasably fastened together. The hook unit comprises a first arm having a first hook at one end and a releasable fastener part at its opposite end, and a second arm with second and third hooks at one end and its other end portion joined to the first arm. The hooks each comprise a point and a curved portion. The curved portions of the second and third hooks diverge, one to each side of a longitudinal axis of the unit, and curve towards the second arm. The first hook curves towards the second arm in a plane through the longitudinal axis. The lure member has a second releasable fastener part and a loop spaced apart along the longitudinal axis. The second arm is releasably fastened to the lure member by cooperation of the first and second releasable fastener parts and by extension of the second arm through the loop.

Abstract: An tunable optical filter of the kind used, for example, in wavelength-division multiplexing (WDM) optical communication systems and tunable source applications, has an interference filter element which is pivotable to adjust the operating wavelength of the filter. In order to reduce polarization dependency as the angle of the interference filter element changes, the light beam to be filtered is passed through the filter element twice, the second time with its polarization state shifted, specifically orthogonal, relative to the polarization state during the first pass. As a result, polarization dependent effects are equalized.

Abstract: In a telecommunications system, automatic directory assistance uses a voice processing unit comprising a lexicon of lexemes and data representing a predetermined relationship between each lexeme and calling numbers in a locality served by the automated directory assistance apparatus. The voice processing unit issues messages to a caller making a directory assistance call to prompt the caller to utter a required one of said lexemes. The unit detects the calling number originating a directory assistance call and, responsive to the calling number and the relationship data computes a probability index representing the likelihood of a lexeme being the subject of the directory assistance call. The unit employs a speech recognizer to recognize, on the basis of the acoustics of the caller's utterance and the probability index, a lexeme corresponding to that uttered by the caller.

Abstract: An antenna suitable for mounting upon vehicles, vessels or aircraft for communication via satellites comprises a conductive ground plane and a radiator element in the form of a conductor helically wound to define a frusto-conical shape with the ground plane as its base. The conductor may be formed upon a dielectric substrate in the shape of a truncated cone. The dimensions of the antenna element are selected so that the pitch angle of the radiator element varies between a minimum of about 6 degrees and a maximum of about 8 degrees. The required pitch angle may be achieved when the cone angle of the frusto-conical shape is between 5 degrees and 20 degrees and the mean diameter of the frusto-conical shape is between 0.3 and 0.47 of a mean operational wavelength predetermined for the antenna. The length of the radiator element is selected to be the minimum needed to sustain a wave.

Abstract: A process is provided herein for extracting organic toxic contaminants including pentachlorophenol, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans, from wood, e.g., utility poles, fence posts, or railway ties. The process comprises extracting the wood with a supercritical fluid in conjunction with an entrainer having wood swelling properties and an agent to break the hydrogen bond between the organic toxic contaminants and the wood, at conventional supercritical fluid extraction temperatures and pressures. The process is further improved by exposing, either in a slurry of the wood phase, or in a liquid phase resulting from such extraction, the contaminants to UV, e.g., sunlight, in the presence of a photosensitizer. The present invention also provides for the photodegradation of a solution of organic toxic chemicals including pentachlorophenol, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans, by exposing such solution to UV, e.g.

Abstract: A cable for use as a distributed antenna in intrusion detection systems comprises an internal open transmission line in parallel with a periodically loaded structure which supports an external transmission line mode of operation, specifically a surface wave, and is "driven" by the open transmission line. The periodically loaded structure may comprise transmission line segments for example cylindrical conductor elements intercoupled by serial inductive coupling. There are no fewer than three and no more than fifteen conductor elements in one wavelength (.lambda..sub.S) of the external transmission line modes. Preferably the length of each transmission line segment is about one quarter of the wavelength (.lambda..sub.S) of the external transmission line modes. The inductive coupling may be provided by resistance wires extending alongside the conductor elements.

Abstract: A bicycle trailer comprises a frame having at its one end a hitch assembly for connecting the bicycle trailer to a towing bicycle and at its other end a ground-engagable wheel. The hitch assembly comprises a clamp part for clamping non-rotatably to a seat supporting part, for example the seat post, of the towing bicycle, a universal joint portion fixedly attached to the trailer frame and a releasable fastening attaching the clamp part to the universal joint portion. The universal joint portion permits pivoting of the trailer, in use, about generally vertical and horizontal axes which are spaced apart, preferably with the second pivot axis between the first pivot axis and the trailer frame. The clamp part may comprise a generally U-shaped member having a cylindrical bight portion and a bolt member extending through aligned holes in end portions of the U-shaped member to urge them together and clamp the seat supporting part.

Abstract: In order to reduce the number of components and avoid relatively long optical lengths, a non-reciprocal device such as a circulator comprises a plurality of ports at one end of the device, a mirror at an opposite end of the device, and a series of optical elements disposed between the ports and the mirror. The optical elements include a first element which spatially separates first and second orthogonally-polarized components of a light beam leaving one of said plurality of ports and passing through the device in a forward direction, and recombines the first and second components as they pass through the device in a reverse direction after reflection. A second optical element, disposed between the separating and recombining element and the mirror, selectively displaces and rotates the light beam components such that the recombined light beam is coupled to a different one of the plurality of ports.

Abstract: In N.times.N optical couplers, such as are used in local area networks and backplanes of telecommunications and computer equipment, which use BRAGG volume diffraction means to couple light beams between the inputs and outputs, the number of gratings is reduced by means of so-called "grating degeneration" one grating can be shared by at least two wave pairs at the same time. In order to achieve this reduction, the directions of light waves in the dielectric slab (or the lateral positions of fibre ends) are suitable arranged. In other embodiments, a reduced number of gratings is achieved by using a "sandwiched" structure which uses multi-layered dielectric slabs. Both embodiments may be combined in the one coupler.

Abstract: A machine gun unit comprises a machine gun mounted to a support by a mounting permitting pivoting movement of the machine gun relative to the support in azimuth and/or elevation. Angle encoders provide position signals representing angular displacement of the machine gun relative to the support. An aiming system comprises a sensor, for example a CCD sensor, which provides a video signal representing a field of view for the aiming system, a display device for displaying the field of view, a manual input interface, a graphics artifact generator, and a digital signal processor (DSP). The DSP monitors the outputs of the angle encoders and controls the graphics artifact generator to combine the output of the graphics artifact generator with the output of the CCD sensor for display by the display device. Various graphics artifacts can be provided. Masks may be provided for delimiting field of fire. A cursor may be repositioned to reflect superelevation requirements.

Abstract: Attenuation of an optical fiber is measured by transmitting an optical signal having a predetermined wavelength to the fiber, and FSK modulating the optical signal with information identifying the wavelength and transmitted power of the optical signal. At a receiver, the optical signal is detected and the information is recovered by demodulation. Wavelength-dependent sensitivity information for the detector is read from a store in dependence upon the wavelength information and used to control the gain of an amplifier for amplifying a subsequently transmitted continuous wave optical signal used for attenuation measurement. The received power level of this optical signal is converted into a digital value and used with the transmitted power information to determine the fiber attenuation at the predetermined wavelength. Reference power levels are determined by connecting a jumper between a port and an external detector.

Abstract: A polarization-independent optical detection apparatus for measuring light output from optical fibers comprises an optical detector having an input port for receiving input light by way of an optical path and an output for a corresponding detection signal. A polarization-transformation element is rotatably mounted in the optical path so that the input light passes through the element to reach the input port. A drive motor rotates the polarization-transformation element in a plane extending transversely of the optical path. The polarization-transforming element is selected to transform the polarization state of the input light reaching the detector, as the element spins, so that, for any given input polarization state, the time averaged electrical signal from the detector is approximately the average electrical signal from the detector over all input polarization states.

Abstract: A mechanically steerable antenna suitable for mobile earth stations of satellite communication systems comprises a support member mounted upon a base member and an active antenna element or array of elements mounted upon the support member. The antenna element or array of elements is rotatable about its boresight relative to the support member. The support member itself is rotatable in azimuth relative to the base member. The rotation axis of the antenna element or array of elements and the rotation axis of the support member are mutually inclined by a predetermined angle corresponding to the mean elevation angle of the satellite. The antenna includes drive means for rotating the support member relative to the base member, and a flexible coupling interconnects the base member and the antenna element.

Abstract: In a system for monitoring and collecting data on the viewing habits of television viewers or radio listeners, to enable operators of networks or television stations, programmers and advertisers to determine the numbers of viewers watching particular programs, a portable personal data collection device comprises a detector for providing a station identifier identifying the particular broadcast signal being received by the receiver, a clock for providing a signal representing time, a memory for storing data, a cellular telephone module for communicating with a central location, a control for the cellular telephone module, and a microprocessor. The microprocessor stores in the memory data comprising the station identification, and the time at the beginning and end of receiving signals from that station. The control is arranged to control operation of the cellular telephone module to transmit the stored data to the central location.

Abstract: In order to reduce size and facilitate incorporation into planar multi-layer microwave integrated circuits, a microwave hybrid, specifically a Magic-Tee, is formed using microstrip circuit elements and aperture coupling. The Magic-Tee comprises a ground plane interposed between dielectric printed circuit boards. The outermost surface of one of the boards carries a Tee circuit comprising microstrip branch arm conductors with a microstrip conductor projecting transversely from its middle, the Tee junction, to form the leg of the Tee. The outermost surface of the other board comprises a line in the form of a microstrip conductor. An aperture is provided in the ground plane at a position between the Tee junction and an underlying part of the line conductor. Various Tee junction configurations, such as Y or .DELTA., may be implemented also. The magic Tee may be an integral part of an MIC or MMIC device.