Abstract: Optical aim-training apparatus 10 (FIG. 1) for a rifle 20, or the like comprises a CRT displaying a target image on a scanned line raster. The rifle is simulated and has photo-detection device 21 contained in a housing 22 located adjacent the barrel 19. The photodetection device has a detection axis 23, aligned parallel with the rifle bore axis, which 23 intersects the screen at detection point 34. The rifle sighting device has a sightline also parallel to the bore axis and detection axis intersecting the screen at aim point 33. The offset between aim and detection points is determined by a calibration procedure and when aim is taken at a target image and the trigger depressed a marker region of raster 29, displaced from the image by the calibration offset, is brightened temporarily. A series of light pulses due to scanning of the marker region raster is detected and the screen location of the center of the detector field of view i.e. detection point 34, found.

Abstract: An information display system includes a raster-scan display screen DS and an information store IS for storing information to be displayed on the screen. The store has a capacity greater than the maximum amount of information which may be displayed at any one time. Display controller DC is operable to generate a succession of screen addresses of successive areas of the display screen DS, and mapping memory MU is provided to translate each screen address into a store address indicating the location in the information store IS of the information to be displayed in that area of the display screen. Display logic DL is provided to produce from the store output the necessary signals for activating the display. Map changes MC are provided to enable the translations effected by the mapping memory MU to be varied as required to change the display. One or more input devices ID allow information to be written into the display store.

Abstract: A demodulator circuit comprises an integrator (A1) having its input connected through a first switch (S1) to a summing point (P). A modulated carrier signal to be demodulated is applied to the summing point through an input resistor (R1). A sample-and-hold circuit comprises a second switch (S2) operable at the carrier signal frequency in antiphase with the first switch (S1) to connect the output of the integrator (A1) to a holding capacitor (C2) and an operational amplifier (A2) having 100% negative feedback. A feedback connection including a feedback resistor (R2) is connected between the output of the amplifier (A2) and the summing point (P).

Abstract: A two dimensional illuminated display for forming on an expansive surface such as an airship envelope comprises (FIG. 3) a set of one dimensional display components 18 each formed by a multiconductor (ribbon) cable 19 having attached thereto by insulation piercing connectors 41 a plurality of display elements 20 containing illumination elements 20.sub.R and 20.sub.G formed by arrays of red and green high intensity l.e.d.'s. The display component cables hang from an attachment point at one end of the cable (21, FIG. 2) and are retained in channels 15, formed on the surface by raised vertically-extending ribs 16, by retaining members 24 extending across the channels by way of through-apertures 25 in the ribs. The retaining members are prevented from withdrawal by similar joining members 26 extending along the ribs. Each illumination element is fed from the cable 19 and the emission axes of the diodes may be tilted relative to the local channel base e.g.

Abstract: An accelerometer system (FIG. 2) suitable for measuring low-frequency accelerations in inertial systems is also able to measure high-frequency vibrational accelerations which give rise to e.g. sculling effects in inertial platform arrangements employing three such accelerometer systems. The system comprises a low-frequency inertial quality force feedback accelerometer 10' and a high-frequency, e.g. piezo-electric, accelerometer 46. The output of h.f. accelerometer 46 is summed at 48 with the feedback signal from transducer 32' in the l.f. accelerometer feedback loop, the faster response of the h.f. accelerometer providing most of the feedback to balance the l.f. loop without significant displacement of mass 11'. Up to several hundred Hz the displacement of mass 11' and the feedback component from transducer 32' is only to overcome the error in the h.f. accelerometer signals and at higher frequencies the response of the h.f.

Abstract: A method of manufacture of a printed circuit board having plated-through holes interconnecting printed conductors formed on each of two external surfaces, includes the step of masking those areas of the external surfaces where solder will subsequently be required to adhere. The unmasked conductive areas are then coated with a material which prevents wetting by normal soldering techniques. The masking material is subsequently removed. The coating material may be electroless nickel, or electroplated nickel or suitable nickel alloys.

Abstract: A constant voltage circuit has two rails 10 and 12, with one rail 12 at a variable potential V, possibly supplied by a voltaic cell. In one arm between the rails there is voltage reference means Z1, 14, with a circuit output line 16 connected thereto, and the line 16 is required to be maintained at a potential V.sub.o, corresponding to a maximum value for V. In a second arm there is provided a first resistor R1, connected to the rail 12, and in series with a transistor T2. A second, equal, resistor R2 is connected between the output line 16 and the transistor T2. Means Z2, 30, T3, causes a potential, corresponding to the variable, decreasing, potential V, to be applied between the second resistor R2 and the transistor T2. The current to the transistor T2 is constant over a wide range dV for V, by a compensating current portion dI flowing through the second resistor R2, thereby maintaining V.sub. o constant.

Abstract: An inertial platform accelerometer cluster (FIG. 1) comprises a cluster of gyro and accelerometer system triads disposed in a cluster housing 10 to detect motion along and about orthogonal x, y and z axes. The orthogonal accelerometer systems each comprises a pair of codirectional accelerometers e.g. 15x, 15'x having an operating bandwidth from 0 to several KHz mounted on the housing walls equidistant from a point 14, which represents a common center of percussion to all pairs, at the center of gravity of the cluster. The analogue output signals of each accelerometer pair are scaled, summed and differenced to provide `sum` and `difference` signals which represent respectively acceleration in the sensitive direction and angular acceleration about an orthogonal axis.

Abstract: An electrical circuit assembly uses a plurality of stacks upon a generally planar support. Each constituent stack has a plurality of modules having planar substrates extending at right angles to a longitudinal axis of symmetry of the stack. The axis of symmetry is perpendicular to the generally planar support and various electrical interconnections extend between adjacent substrates parallel to this axis. Electrical circuit elements are mounted upon the substrates and the substrates are spaced to facilitate flow of cooling fluid, such as air, between the substrates. Heat conducting fins may be mounted on the substrates. To facilitate flow of cooling fluid, stacks of substrates are staggered or offset from substrates of an adjacent stack. A plurality of the electrical circuit assemblies may be combined together.

Abstract: A circuit for converting a TV receiver to operate in accordance with the system associated with received signals, there being either F or F' scan lines in a field, with F<F', includes a counter driven by pulses each representative of one end of a raster scan line, and having M stages, with F and F'<M<2F and 2F'. There is also means to preload the counter selectively with a count of R or R', where (M-2R)=F and (M-2R')=F'. Wide window means detects when a field sync pulse is within a window including the (M-R)th and (M-R') stages, and, in response, the counter, initially, is preloaded with R'. Decision logic means then detects whether a field sync pulse occurs after the Kth stage, with K=M-[R+R']/2, when R' is continued to be preload; or occurs before the Kth stage, when R subsequently is preloaded; and the required TV receiver conversion is completed.

Abstract: Measurement-expressing apparatus for monitoring (n) switches, the state of each switch representing the state of a station, has a resistor in parallel with each switch, the (n) resistors having binary related resistances, a constant current is supplied to the parallel combinations of switches and resistors connected in series with each other, and signals each representative of the sum of the voltage drops within the series of parallel combinations are operated upon by an n-bit analogue-to-digital converter, the (n) outputs of the converter each being individually associated with a parallel combination, in each quantization period (t) of the converter, a signal is obtained on each converter output representative of one of the two possible states of the corresponding station, and signals of one form, provided on at least one output individually are accumulated in a counter over an interval (mt). The numbers accumulated by any counter in each of a plurality (p) of intervals (mt) are operated upon.

Abstract: A temperature-independent gain control circuit includes a dual-gate MOSFET having the input signal applied to one gate and a resistance connected to the source. Control means are provided which are responsive to a control voltage to control the voltage between the other gate of the MOSFET and the end of the resistance remote from the source in such a manner as to maintain the drain current of the MOSFET proportional to the control voltage.

Abstract: In film copying apparatus (FIG. 3) in which a master film 13 and unexposed copy film 13 are drawn past an exposure gate 12 by a drive sprocket 15, the sprocket teeth 16 have a curved profile which engage with film sprocket holes such that the upper film lags behind the lower and the copy is incorrectly aligned with respect to the sprocket holes. Film strip registration means for correcting misalignment at the exposure gate comprises suction means 20 having a vacuum chamber 21 with apertured pad 23 by which the copy film is diverted out of the plane of the master film thereby increasing its path length between exposure gate and drive sprocket and advancing it at the exposure gate to re-establish registration with the master film.

Abstract: An electrical circuit assembly comprises a stack of a plurality of substantially identically constructed modules, each module includes a planar, electrically insulating substrate having constituent elements of a circuit on only one major surface of the substrate, and has an electrically conductive coating on the other major substrate surface. The assembly has at least one conductor member, at least partially, holding the modules in their required locations in the stack, each conductor member and the conductive coatings being interconnected, and together forming an extensive body, to be maintained at zero potential, to reduce electrical interaction between the circuit elements. Each conductor member may be planar in shape, or may comprise a corner piece for the stack. A plurality of stacks on a common support may have a common module, and/or share a common conductor member, and the support may provide a conductor member.

Abstract: A radar system includes signal processing means (SP) operable to determine the velocity relative to a receiving antenna (AR) of each object from which transmitted radiation is reflected. The signal processing means delivers signals representing the relative velocities of objects in each of a number of predetermined ranges of velocity values. Storage means (SM) are provided which comprise, for each increment of antenna bearing, a separate storage location for each of the ranges of velocity values. Circuit means (CM) are operable to read out the contents of the storage means and to modify signals delivered by the signal processing means (SP) in accordance with the contents of the storage means (SM) to provide output signals. In addition the circuit means (CM) is also arranged to further modify the output signals to provide new contents for the storage means.

Abstract: An optical element for location between a source of radiation and a detector (13) includes a first optical surface (10) have a central transmissive area (11) and a surrounding area (12) reflective to radiation from direction of the detector (13). A second optical surface (15) is spaced from the first surface (10) towards the detector (13) and has a central reflective area (16) arranged to reflect radiation passing through area 11 towards the reflective area 12. A transmissive area (18) of the second surface (15) surrounds the central area (16), and is itself surrounded by a reflecting area (17) concentric with the detector (13) and forming a reflective shield for the detector.

Abstract: The apparatus includes a two-coordinate array of radiation sensitive devices each operable to cause the storage of a charge proportional to the intensity and duration of radiation received. A storage element is associated with each sensitive circuit and a transfer mechanism is operable to transfer the charge from each sensitive circuit to its storage element to define a radiation image frame. A register is arranged in the same two coordinate array, and a shift mechanism operates to transfer charge from the storage elements to the register in parallel bit streams defined by one of the two coordinates. Differential detectors compare corresponding bits shifted into and out of the register and the presence of a detector output exceeding a threshold level causes the detector outputs to be sampled into an output register. The contents of the output register are shifted out serially to determine the position in the radiation image frame of each output register bit position producing a detector output.

Abstract: In an electrical circuit assembly a stack of modules is secured in a bore through a casing, there are longitudinally extending grooves in the internal surface of the casing, and electrical interconnections each have a part both extending from a module and protruding into a groove, and a part in the groove. The electrical interconnections, the constituent electrical interconnection parts, if initially separable, and possible insulating members in the grooves between some electrical interconnections, are secured, and required electrical connections are made, by these circuit assembly parts being clamped together in the grooves. The stack may be clamped in the bore. The clamping means may include end covers for the grooves and/or for the casing bore, and the end covers may be in resilient engagement with, respectively, the electrical interconnections, and/or the module stack.

Abstract: A control system for positioning a marker on a cathode-ray tube display (18) includes position registers (16) operable to store the position of the marker on the screen. Input means (11) generate signals which represent desired changes in the position of the marker. Comparison means (15) response to these signals to produce an output pulse corresponding to each increment of change in the position of the marker. Control means (14) control the operation of the comparison means. Frequency-sensitive means (17) are provided to control the rate at which pulses are applied to the position registers (16).

Abstract: Apparatus (FIG. 1) for non-dispersive optical determination of the concentration of an identifiable gas, such as a hydrocarbon, in a mixture such as atmospheric air comprises a sample chamber 13 to contain a sample of the mixture, a source 21 of IR radiation at a wavelength absorbed by the gas beamed through the sample chamber to a detector 22 and transducer means to change the gas pressure within the chamber to determine the change in radiation intensity detected at different pressures. One wall of the sample chamber is formed by a flexible diaphragm 25 driven by a voice-coil type transducer 26 whereby the pressure is switched repetitively between the values above and below atmospheric. Atmospheric gas is admitted to the chamber by a porous plug 24 which restricts flow to a low level permitting a pressure change in the chamber. Absorption by the gas relates the intensity of source radiation I.sub.S and measured radiation I.sub.M by I.sub.M oc I.sub.S .multidot.e.sup.-.alpha. o.sup..multidot.g.multidot.p.