Abstract: Before modulating the transmission carrier, each binary data signal is individually coded as a discrete symbol belonging to a PSK constellation of N symbols which are combined with N discrete points to produce two binary signal streams of which the first is in phase with the incoming signal while the second is in phase quadrature with said incoming signal. Each of said two binary signal streams is assigned its own signature by combining it with a discrete spreading code to produce two spread composite signal streams each of which is to be applied to a modulator. Both of said spreading codes are substantially orthogonally cross-correlated. The method may be used in a satellite communications system, in particular for digital sound transmission and communication via land microterminals.

Abstract: A circular polarization antenna whose radiation pattern is in the shape of a body of revolution about an axis and has a radiation minimum in the direction of this axis comprises a reflective conductive surface which is essentially in the shape of a body of revolution about the axis. A rectilinear conductive rod extends axially from a first end at the level of and isolated from the conductive surface to a second end and is connected at its first end to an excitation line. A plurality of radiating arms each have a first part extending in an essentially radial plane from the second end of the conductive rod. This first part is electrically connected at its proximal end direct to the conductive rod and is extended at its distal end by a curvilinear rod typically lying on the surface of a sphere centered at the second end and whose general direction is inclined relative to the radial plane.

Abstract: The apparatus comprises: an array of N radiating elements, subdivided into P subarrays of M elements each, each beam of a specified pattern using a plurality of elements selected from the elements of at least some of the subarrays; a common signal source; power divider means having one input and N outputs to distribute the signal delivered by the source; amplifier means for amplifying said signal; and means for selectively exciting at least some of the elements with the amplified signal at a controlled phase shift so as to obtain the radiation pattern specified for the antenna.

Abstract: A photon signal received on a CCD is digitized and coupled to a 3.times.3 pixels data analysis array (DAA). The digital signals read out from the penultimate three pixels of the DAA are used to address a first look up table held in a memory, the digital signals read out from the last three pixels of the DAA are used to address a second look up table held in a memory. The data stored at the two addressed locations are then read out and logically ANDed to produce an output signal only when both ANDed data correspond to a valid photon event. The output signal thus defines the position of the center of the photon signal at a high level of precision.

Abstract: The invention relates to cryogenic apparatus of the open cycle kind comprising a reservoir 1 for storing cryogenic fluid in liquid-vapor phase equilibrium and a phase separator 2 presenting an inlet 3 communicating with the inside of the reservoir and an outlet 4 for liberating gas, the inlet including an obturator 6.The technical problem is to provide an apparatus of simple operation with minimal dissipated energy.According to the invention, the phase separator 2 comprises a transfer chamber 9 with a constriction 5 at its inlet, and a further obturator 8 at its outlet, the two obturators 6,8 being operated alternately by a control unit 10.The invention is particularly applicable to zero-gravity operation, especially for space missions.