Abstract: An optical image projector suitable for projecting symbols in an artwork generator comprises a projector head beam relative to which a photographic film 16 can be positioned accurately. The head contains a source 11 of a beam able to illuminate an array of transparencies mounted on a carrier 17 which carrier may be moved between positions accurately defined by a detent mechanism 19, 20 to locate different arrays in the beam. A masking member 21 forming part of the projector head is movable past the carrier and interrupts the beam to prevent projection of all the symbols of the array but has one or more apertures 25 which can be aligned with any one transparency at a time to allow projection. Because the carrier need carry relatively few arrays it can be accurately positioned repeatedly within the projector head to align a symbol accurately with respect to the film while the masking member aperture may be positioned with only moderate accuracy for each of the larger number of transparencies.

Abstract: A monitor (FIG. 1) of disturbances of normal voltage/current parameters of a power line 12 consists of input A/D conversion means 18 by which the actual parameters are sampled and digitized and applied to a store 36 controlled by a main microprocessor 30. A real time clock also provides time markers which are stored as flags with the sample data. The store has a plurality of locations which are addressed in a loop whereby newly digitized sample data replaces that stored previously. A secondary microprocessor 54 also receives the digitized measured parameter data which it compares with stored nominal parameter data to detect a disturbance, the detection causing the store to store subsequent sample data sequentially in different locations. Thereafter the main processor reads the data from the store to provide samples stored prior to, and subsequent to, the disturbance and the real time relationship between them.

Abstract: An automatic speed controller for a universal, series-wound, electrical motor, is part of a system whereby the motor is energized by a A.C. supply from control means including a triac, in turn, controlled by the speed controller. Within the controller signals are derived comprising solutions of the equation: ##EQU1## or a derivative thereof, or an approximation thereof, where N is the armature speed, R.sub.a is the resistance of the armature, K is a constant dependent upon the motor design, (V.sub.a -I.sub.a R.sub.a) is the true average of the alternating quantity (v.sub.a -i.sub.a R.sub.a), where v.sub.a and i.sub.a are, respectively, the instantaneous armature voltage and current, and .0..sub.AV is the true average flux in the magnetic circuit of the motor, both true averages being obtainable when the motor is operating under steady state conditions.

Abstract: An optical scanning system includes scanning means arranged to scan an object field and comprising, in one form, a rotatable drum (10) carrying a plurality of pairs of mirrors (12, 13). A detector (21) is provided which is sensitive to optical radiation directed on to it by the scanning means. Means, such as telescopes (17, 22) collect radiation from at least two fields of view for presentation to the object field of the scanning means. Optical switching means are provided so that radiation reaches the detector (21) from each field of view in turn. The switching means may be an optical shutter (14) having reflective regions (15) and transparent regions (16).

Abstract: A signal switch and combining system for a radio communication system having two receivers (R.sub.A, R.sub.B) includes a comparator operable to determine which of the receiver output signal to noise ratios is the greatest at any instant. There is also a threshold detector arranged to determine when the difference between the two signal to noise ratios exceeds any one or more of a number of predetermined threshold levels. A gating network (GN) responds to the outputs of the comparator and threshold detector (CT) to control a switching and impedance network SZ. This controls the connection of ratio signals from the two receivers (R.sub.A, R.sub.B) to an output load. The network is arranged to connect to the load either one of the two radio signals or a combination of the two signals in one of a number of predetermined ratios. The signal to noise ratios of the two receiver output signals are conveniently indicated by the receiver automatic gain control signals.

Abstract: A circuit assembly comprises a planar substrate 10 supporting, on a surface 11, connectors 14 and modules 12, the connectors having a common bridging member secured to the substrate and permits movement of an electrical insulating block 15 of each connector in a plane normal to the surface 11, to ensure that the manufacturing tolerances in relation to the block are larger than otherwise would be required, and to facilitate alignment of the block in a predetermined position, when the connector is mated with an associated connector 20 (shown in FIG. 2). Possibly, aligning means for example, comprising pin and hole arrangements is provided, a part of which aligning means, for example, comprising holes 40 and 41, is provided within at least the insulating block of the connector of the circuit assembly, to co-operate with a complementary part, of pins (not shown), of the aligning means provided within the associated connector.

Abstract: Microwave phase-shifting apparatus includes a section (20) of waveguide of circular cross-section having a closed end (23) and an open end. A fixed phase-shifting member (20) is located within the section to convert plane-polarized incident energy to circular polarization. A rotatable shaft (27) of dielectric material projects through the end wall of the section along the longitudinal axis, and carries a rotatable element (28). This element is of such a form and in such a position that linearly-polarized microwave energy entering the waveguide section is reflected out of the section with a reflection coefficient having a phase angle component which may be continuously adjusted over a range of 360.degree. by rotation of the shaft, in either direction.

Abstract: A data processing system for pre-planning the flight of an aircraft includes a plotting board arranged to supply position coordinates of selected points on a route to a processor. Other inputs to the processor provide details of known aircraft parameters such as speed, fuel load, fuel consumption and bank angle. The processor determines from these inputs for each leg of the flight variable factors such as track heading, flight time, fuel used and fuel remaining. The inputs and outputs of the processor are recorded on a suitable medium.

Abstract: A liquid display device comprises two spaced electrodes each having a resistance characteristic such that a potential gradient may be developed across the electrode. A liquid crystal material is located between the two electrodes. Voltage supply means are provided which apply an alternating potential across each electrode, such that the two potentials are of the same frequency, and, preferably, in quadrature with one another.

Abstract: A circuit assembly has at least one component comprising a thin film module, or a discrete component, with leads extending therefrom, the assembly also including a substantially planar substrate supporting the component, and at least one connector with a block of electrical insulating material either adhering to or integral with the substrate, and with a plurality of connector pieces, secured to the block, co-operating with the leads, and comprising terminals of the circuit assembly.