Abstract: A patient support system for irradiation therapy or treatment simulation comprises a main arm 1 on a sub-floor mounted pivot 10 about a first vertical axis 17, which supports a further arm 49 rotatable about a second vertical axis 16. At the other end of the arm 49 a vertical pillar 4, pivotable about a third vertical axis 15, supports a vertically displaceable carriage 3 on which a patient support table top 2 is directly mounted. A control system is described which enables x, y coordinate command values to control respective drives associated with the three vertical axes to position a patient quickly and accurately relative to the treatment isocentre.

Abstract: A method of a device for determining the spectral distribution of a nuclear magnetization in a limited volume, wherein each sequence of r.f. and gradient excitation comprises a sub-sequence which dephases the nuclear magnetization everywhere outside a defined layer. This sub-sequence is followed by three r.f. pulses, the first two of which are layer-selective. These three r.f. pulses excite the nuclear magnetization in an area of intersection between said layer and two layers which extend perpendicularly to one another and to said layer. In order to suppress undesirable FID signals and to enhance the spectrum, phase cycling is performed.

Abstract: A method of scanning objects by means of ultrasonic echography, including the transmission of ultrasonic waves to the object to be scanned by means of a transducer array (101) and the reception and processing of the echographic signals corresponding to the echoes returned. Digitized A-lines are divided into n elements of p points and, after various operations, the reconstruction of the elements of the echographic lines by selection of principal vectors which imply factors which imply a reconstruction of the matrix sum of the series of unity matrix products relative to said selected principal vectors.

Abstract: A method is provided for controlling the movement of an object 1, 61, in an environment 64. The method involves making predictions of collisions, given the outlines of the object and the environment, so that avoiding action can be taken. The object and environment are modelled as clusters of interpenetrating spherical bubbles, the model comprising the relative positions of the centers 6, 7, 8, 9, and 21 to 28 inclusive of the bubbles and their respective radii. The model simplifies the prediction of the point of collision of two such modelled objects by examining the collisions between bubbles only. An early, safe, approximate prediction of the collision can be obtained using Newton's approximation.

Abstract: In an X-ray apparatus utilizing a fan-shaped X-ray beam the thickness of the beam is determined by a collimator of variable aperture. The X-ray beam irradiates a patient to be examined and is subsequently detected by a detector array. An image of a patient can be formed from detector signals. Using a variable aperture of the collimator, comprising two slats which are pivotable in opposite directions and a collimating side of which is provided with an X-ray absorbing material, the thickness of the X-ray beam can be varied, and hence also the thickness of the slice to be imaged.

Abstract: MR spectroscopy method and apparatus in which an examination zone is exposed, preferably repeatedly, to a sequence which comprises a first binomial 90.degree. RF pulse, a 180.degree. RF pulse and a second binomial 90.degree. RF pulse which sequence enables separate demonstration of the presence of either lactic acid or lipids in the presence of water. The periods in time between the two binomial RF pulses and the 180.degree. RF pulse are equal and are approximately at least to the reciprocal value of four times the scalar coupling constant of lactic acid.

Abstract: A pipeline system which is suitable for the processing of data accompanied by data identifying signals comprises interconnected modules which process the data and which controllably transfer the data to one another. Data processing in a module introduces a delay of the data. For correct data processing in a module, the data identifying signals must be in synchronism with the data. In a pipeline system in accordance with the invention, the data identifying signals are applied in parallel to all modules, these signals being delayed in a module by a delay means until the data whereto the signals relate have reached the relevant module. The foregoing has the advantage that the number of connections between the modules is reduced.

Abstract: A pneumatically powered valve actuator is disclosed and includes a valve actuator housing, a working cylinder within the housing having a pair of opposed contoured end faces, and a main piston reciprocable within the cylinder along an axis. The main piston has a pair of oppositely facing primary working surfaces contoured substantially the same as the opposed end faces of the working cylinder to mate therewith providing a small minimum volume and, therefor, a high compression ratio. A pair of air control valves are reciprocable along the axis relative to both the housing and the main piston between open and closed positions for selectively supplying high pressure air to the piston primary working surfaces. The contoured end faces each include a central opening, an outer annular flat surface, and an intermediate frustoconical surface connecting the central opening and the flat surface.

Abstract: In a teletext decoder circuit the character generator supplies picture elements at a rate of nominally approximately 6 MHz under the control of display pulses occurring at the same rate. These display pulses are derived from reference clock pulses which occur at a rate which is not a rational multiple of 6 MHz. The character generator comprises a generator circuit which receives the reference clock pulses and selects, from each series of N reference clock pulses, as many pulses as correspond to the number of horizontal picture elements constituting a character, while the time interval of N reference clock pulses corresponds to the desired width of the characters to be displayed. The character generator supplies picture elements of distinct length, while the length of a picture element is dependent on the ordinal number of this picture element in the character.

Abstract: A magnetic resonance imaging apparatus includes an r.f. coil which is comprised of a number (for example, two in the case of a surface coil and four in the case of a cylindrical coil) of coaxial cables. The outer jackets of the cables are arranged so as to form a sleeve enclosing the core or center portion at the area of a node in the electric field. By keeping lead-out portions of the cables outside the sleeve, a highly interference free coil is obtained. The total cable length amounts to, for example, 3/4.lambda., with 1/4.lambda. as a lead out portion and 0.1.lambda. as a sleeve core defining the coil circumference.

Abstract: A teletext decoder is provided with a page memory having rows (R0 to R73) for storing corresponding packets of teletext data, the page memory being provided with at least one extra memory bit (F1, F2) for each row thereof, the extra memory bits constituting flags (F1, F2) which may be selectively set by the processor software in order to initiate selective action in respect of those packets which correspond to the flagged rows. The selective action might be to permit or prevent packets being written into memory or to alert the processor that immediate processing of a flagged packet is required.

Abstract: A bistable electromechanical transducer is disclosed having an armature reciprocable between first and second positions, a permanent magnet latching arrangement for maintaining the armature in the respective positions, and an electromagnetic repulsion arrangement operable when energized to dislodge the armature from the position in which the armature was maintained and causing it to move to the other of the positions. In a preferred embodiment, the transducer takes the form of an electronically controllable valve mechanism for use in an internal combustion engine and has an engine valve with an elongated valve stem along with the electromagnetic repulsion arrangement for causing the valve to move in the direction of stem elongation between valve-open and valve-closed positions.

Abstract: MRI utilizes so-called multiple-slice multiple-echo pulse sequences. Pulse sequences are generated in order to produce echo resonance signals in different sub-regions of a body, after which images of the various sub-regions are reconstructed from the resonance signals. The pulse sequences, for example spin echo sequences, are successively generated for the various sub-regions. More than one echo resonance signal can be generated by means of each pulse sequence. In order to reduce the overall measuring time the invention proposes the interleaving of a pulse sequence (ex1, ep11, er11, ep12, er12) for a sub-region with pulse sequences (ep02, er-12, ex2, ep21, er21, er02, ex3, ep31, er31, ep22) for other sub-regions. It is essential that the excitation pulse (ex1), the echo pulses (ep11, ep12) and the echo resonance signals (er11, er12) are phase coherent within a pulse sequence.

Abstract: A system for video recorder programming using existing television broadcast teletext transmissions. The programs required are chosen from schedules displayed on teletext pages, the necessary control information is loaded automatically into a video recorder, and program labels are transmitted to ensure that the correct programs will be recorded even if program timings are altered. All the control information for achieving the above are fitted into the coding structure of a teletext transmission using extension packets additional to data packets containg display data. The invention also extends to a video recorder with its own teletext decoder for processing the control information.

Abstract: A teletext decoder arrangement has a page memory comprising a large number of chapters or portions in which individual pages can be stored. The arrangement has a plurality of data acquisition circuits which can acquire separate pages simultaneously. A register file is provided having a word location for each data acquisition circuit. A processor can load a memory chapter pointer byte into a word location when a page is to be acquired by the related data acquisition circuit so as to allot the memory chapter identified by the pointer byte for the storage of that page. In a practical embodiment four 4-bit word locations can have any one of 16 different 4-bit pointer bytes loaded into them to identify any one of 16 different memory chapters.

Abstract: Device for receiving and processing road information messages transmitted in digital form, each message including at least a first section for indicating the zone of the road network to which the message refers, which device includes for the control of the data processing a data processing unit which is connected to a bus for the transfer of data, to which bus are also connected a reception memory for temporarily storing the received messages, a selection unit enabling the selection from among the stored messages of those concerning a zone to be designated and a presentation unit for presenting the selected messages.

Abstract: An arrangement for combating intersymbol interference and noise, which are introduced into a data signal (a.sub.k) transmitted at a symbol rate 1/T by a dispersive transmission channel (CH), comprises an adaptive equalizer (EQ) with a symbol detector (ID) for forming tentative symbol decisions (a.sub.k) as well as a post-detector (PD) for forming final symbol decisions (a.sub.k-M) using an auxiliary signal which is derived from the transmitted data signal (r.sub.k) at the input of the arrangement. By using a priori knowledge of the main character of the transfer characteristic of the transmission channel (CH) and by using as an auxiliary signal for the post-detector (PD) the input signal (a.sub.k) of the symbol detector (ID) in lieu of the transmitted data signal (r.sub.k), this post-detector (PD) can be arranged in a non-adaptive and thus simpler way without a resulting noticeable loss of transmission quality. (FIG. 4).

Abstract: A PABX cordless telephone system comprising a base station (10) and a plurality of handset (HS1 to HS5). The base station is connected to the public switching network and communicates with each handset by way of a respective duplex radio link. The operation of the PABX system is controlled by a micro-controller (16) in the base station. Micro-controllers are also present in each of the handsets. Security in the radio communication via the duplex radio links is provided by assigning an n-bit security address code, where n for example comprises 16 bits, to each handset. The signalling protocols in setting-up calls require the transmission of the full n-bit security code. In the interim periods the base station (10) carries out a security check on the handsets forming its system.

Abstract: A device for counting events, such as deposit of coins, providing a control signal after an easily preset number of events has been counted. A binary counter has a parallel output register, with a simple switch and diode connected between each output terminal of the register and a common signal conductor. Individual switches are set to the binary number corresponding to the desired count, so that the voltage on the common conductor changes when the count equals or exceeds the binary preset number. When the circuit receives on electrical signal to be counted, a delay circuit prevents counting for some minimum interval of time, to prevent false counts due to switch bounce or other disturbances which may be related to the event. Energy is stored within the device to maintain the stored count for a short period of time in the event of power interruption between receipt of a first signal to be counted and provision of a control signal when the preset number of counts has been reached.

Abstract: A digital echo canceller [1] with a good protection against double-talk comprises a first filter [9] for the echo cancellation proper, a second adaptive filter [11] for making continuously adapted filter coefficients available to the first filter [9] and gate means [15] which will only apply the adapted filter coefficients to the first filter [9] if certain conditions are satisfied. In the echo canceller [1] a specific filter combination is used, in which the first filter [9] is a time-domain programmable filter (TDPF) and the second filter [11] is a frequency-domain block-adaptive (FDAF), and further means [20,20(1)] are provided that are arranged in cascade with the gate means [15] for transforming the frequency-domain filter coefficients [W(p;m)] of the FDAF [11] into time-domain filter coefficients [w(i;m)] for the TDPF [9].