Abstract: A method of detecting a submerged vessel in or near the wake of a ship in which a plurality of optical fiber sensors are trailed from said ship and in which at least one of said sensors which is located in the ship's wake comprises a magnetically-responsive optical fiber sensor.

Abstract: An asynchronous time division multiplex switching arrangement comprises a serial to parallel converter arranged to receive input packets of data which include routing information, in serial form and convert the packets of data to parallel form. A random access memory is provided in which each packet of data is entered at an addressed location into the memory, and the address is entered in a respective first-in first-out output queue at the tail. The address at the head of the queue is accessed and the packet of data is read from the random access memory into a parallel to serial converter and the packet of data is serially delivered to the associated output.

Abstract: A D-type, master/slave, flip-flop is described for use as a divide-by-2 frequency divider in which a frequency to be divided is input as a clock signal and the Q output is connected to the D input, and in which the master section and the slave section consist only of tracking means, latching being effected by using potentials established on tracking transistors of each section during the previous clock pulse.

Abstract: A phase detector for a phase locked loop frequency synthesizer, in which frequency-divided signals from a variable frequency oscillator and a reference oscillator are used to trigger respective ramp waveform generators, and a sample pulse generator is arranged to be responsive to the reference ramp waveform to provide sample pulses centered at the mid-point of that ramp waveform to respective sample and hold circuits, the relative phases of the ramp waveforms being determined from the sampled and held voltages.

Abstract: A modulator circuit comprises an input for receiving an audio frequency (AF) signal, an oscillator circuit for providing a carrier wave signal, a mixer circuit for mixing the AF input signal with the carrier wave signal to provide an AM modulated signal, a switch having a first position in which the AM modulated signal is provided to an output and the switch having a second position in which the AM modulated signal is provided to a vector adding circuit where the AM modulated signal is vector added to the carrier wave signal, and the circuit including phase shift circuitry for shifting the phase of the AM modulated signal prior to vector adding with the carrier wave signal whereby to provide an FM modulated version of the AF input signal on the oscillator carrier wave.

Abstract: A fibre optic sensor 1 comprises a body 2 of a matrix material which includes an embedded length of optical fibre 3. When the body 2 is exposed to an external disturbance, mechanical and strain forces arising internally can be transmitted to the fibre 3 and will modify the passage of light therein. Pulsed light through the fibre 3 can be sensed for example by interferometry to measure the disturbance. This can provide an inexpensive and sensitive sensor construction which is capable of the remote detection of various parameters.

Abstract: A dielectric bolometer thermal detector of infra-red radiation comprises a layer of dielectric bolometer material, a thermally insulating layer therebelow, a pair of electrodes located on one and the same side of said layer of dielectric bolometer material, a source of bias voltage for providing a bias voltage to said electrode so as to provide a bias field in said layer of bolometer material and a pair of read out contacts respectively connected to said electrodes. A signal which appears between said contacts in response to the application of radiation to said layer of dielectric bolometer material constitutes an output of the detector.

Abstract: A GMSK radio receiver for operation in the presence of strong multipath interference, comprising a baseband frequency converter which operates so as to produce I and Q baseband GMSK signals, which will be distorted by any multipath interference present, which are correlated with a plurality of different possible signals to afford in respect of each correlation a probability signal, the probability signals being processed to determine the significance of the signal received, whereby the transmitted data is determined in the presence of multipath interference.

Abstract: A method of forming optical waveguides is described in which a film of a novolac resin is deposited on a transparent substrate and a dopant material is incorporated into the film during or after the coating step. Additional quantities of the same or different dopant may be incoporated into the dried film by solvent assisted indiffusion.

Abstract: The invention describes an optical data storage medium in which the optical contrast of stored data bits is enhanced by the use, as a photosensitive material or as an additional photosensitive material, of a layer of a photochromic fulgide.

Abstract: A close-spaced diode array in which connection to driver circuitry is enabled by application of a flip-chip solder bonding technique. Not only does this allow dense packing, high pixel content to be achieved but has concomitant advantages of increased light efficiency and improved heat sinking.

Abstract: A digital data interface for high speed asynchronous data transfer is described. The design is nominally intended for integration onto the component chips in communications systems. The system is described with respect to its realization in CMOS IC technology. The techniques involved, however, may easily be applied to other technologies. The interface employs Manchester Bi-Phase Mark encoding of the clock and data to allow extraction of the clock and data signals at the receiver. Furthermore, use of this Manchester code allows code violations to be easily employed as frame markers for synchronization means. The essence of the clock extraction and data detection circuit is the use of calibrated delay line elements to suppress data transitions within the coded input signal, thus allowing the clock transitions to be detected from which the clock is then generated.

Abstract: A circuit arrangement comprising, for each bit location in a column of a RAM, an input shift register, a multiplexer and a comparator. The input data bit is stored in the shift register, and the multiplexer is arranged during a write cycle, to write the data bit into a bit position. During a verification cycle, the multiplexer is arranged to write the inverse data bit into the same position, and the comparator compares the output bit position of the RAM with the inverse data bit. The result is stored in the shift register, which can be down-loaded for analysis.

Abstract: A thin film deposition process for depositing a metal oxide layer onto a substrate body, the process comprising the steps of taking a metal organic compound in vapor form, the compound being capable of absorbing light in the wavelength range of 240 to 400 nanometers, heating the substrate to a temperature below the pyrolytic decomposition temperature of the compound in the presence of the vapor, directing light towards the substrate to cause a photochemical fragmentation of said vapor molecules, the reaction resulting in a deposition of the required oxide on said substrate.The metal organic compound may be a metal alkoxy substituted beta-diketonate such as aluminium diisopropoxide acetyl acetonate.

Abstract: A data pathchecking system for resolving data transfer errors in a plane of directly connected switching elements, the system checking the plane of directly connected switching elements by designating one switching element with an associated control element as a master and other switching elements and associated control elements as slaves. The master switch element instructs other switch elements discretely to check their respective switching element for data transfer errors and checks its own switching element for data transfer errors. Furthermore, the master switch is arranged to validate connections between switching elements.

Abstract: A fluid compressor comprises a casing containing liquid and having located within it a shaft driven radial impeller for pressurizing the liquid before it is fed to a further rotatable structure. By rotation of the impeller and the further rotatable structure, the high pressure liquid compresses a gas or vapor within the compressor casing and expels it from the casing through an outlet port therein. The high pressure liquid inlet end of the rotatable structure is partially shrouded by a shroud structure to restrict the input of high pressure liquid to part of the rotatable structure. The shroud structure has an opening therein which allows the high pressure liquid entering the rotatable structure to be depressurized and returned to the inlet end of the radial impeller after compressing the gas or vapor. By so doing, further gas or vapor for compression will be drawn into the compressor casing.

Abstract: The invention relates to an optical data recording method which comprises addressing a recording device using an infra-red laser modulated with a waveform of the information to be recorded, wherein said recording device comprises an infra-red absorbing material and a photochromic fulgide which is converted into its colored form under the influence of the heat absorbed from the laser, and updating the recording by erasing undesired previously recorded data using a laser operation in the visible region of the spectrum.

Abstract: A flip-chip solder bonding structure having first and second components. Each component is made from a substrate haivng on one surface an array of solderable pads. Selected pads have solder bumps deposited thereon with each surface having a plurality of alignment marks formed thereon whereby when the components are positioned face to face, the arrays register with one another to enable a solder bond to be formed. The respective pluralities of alignment marks may be inspected to assess their relative positions in order to determine the accuracy of the solder bond. The solderable pads and the alignment marks on each surface are formed during the same processing stage as metallized regions. The solder bumps are applied to the metallized regions forming the alignment marks.

Abstract: An underwater sensing arrangement in which hydrophones are embodied in horizontally disposed arms of a hydrophone support structure adaptive to be suspended below the surface of the water and in which the support arms are elliptical and orientated so that they present the lowest resistance to horizontal flow of water past the structure and present the highest resistance or drag against movement.

Abstract: A universal cell, for use in fabricating a custom analog circuit from a standard semiconductor wafer containing a plurality of such cells, includes a semiconductor pocket of a first conductivity type having a surface. At least two regions of second conductivity type opposite to the first conductivity type are formed laterally spaced from each other in the semiconductor pocket. At least one region of the first conductivity type is then formed in one of the at least two regions of second conductivity type. Electrical interconnects are then provided to interconnect one or more of the at least two regions, the pocket of semiconductor material and the at least one region of the first conductivity type to form a selected structure such as an NPN transistor, a PNP transistor, a resistor or a diode. A plurality of identical cells of this type are formed in a semiconductor die and can be selectively interconnected to form any one of a large number of analog circuits.