Nexter Systems and Telecom Bretagne | Date: 2017-09-06
The invention relates to a reflective cell (1) comprising at least two substrates (2a, 2b) each covered with an electrode (3a, 3b) and arranged opposite one another, the substrates defining therebetween a space (4), which separates same and is filled with a bistable liquid crystal material (8) with threshold field, for example a cholesteric liquid crystal, the two electrodes being intended for being connected to a voltage source (5). Said cell is characterised in that at least one of the electrodes (3b) is formed by the association of a pattern (6) that does not cover the entire surface of the substrates (2b) under consideration with a conductive layer (7) that covers the surface of the substrate under consideration, the material of the layer being less conductive than the material of the pattern.
Thales Alenia and Telecom Bretagne | Date: 2010-09-10
A connection device for high frequency signals includes a printed circuit on one external face of which is printed a transmission line and a coaxial connector surface mounted on the printed circuit on the external face. The invention is of particular use for the transmission of radiofrequency signals in the X band, in particular for frequencies from 9 to 10 GHz. The transmission line is connected to the connector by means of a bump contact belonging to the transmission line to which is attached a central core of the connector. The printed circuit comprises at least one internal ground plane parallel to the external face and contributing to the matching of the transmission line. The invention aims to improve the transparency of the transition between the connector and the transmission line. According to the invention, the internal ground plane is perforated by means of a resist facing the bump contact.
Andriulli F.P.,Telecom Bretagne
IEEE Transactions on Antennas and Propagation | Year: 2012
A new analysis of the spectral properties of Loop-Star and Loop-Tree decompositions is presented in this work. The analysis will shed light on the behavior of these decompositions when used with regular operators such as the magnetic field and the Calderón preconditioned electric field integral operators. This work will explain the ill-conditioning problems reported in literature and will provide a family of efficient algorithms to solve the ill-conditioning and regularizing several Loop-Star/Tree decomposed equations of interest for applications. The theory will be corroborated by numerical results that will show the practical impact of the theoretical developments. © 2012 IEEE.
Telecom Bretagne | Date: 2011-08-25
A learning and decoding technique is provided for a neural network. The technique involves using a set of neurons, referred to as beacons, wherein said beacons are binary neurons capable of assuming only two states, an on state and an off state. The beacons are distributed in blocks of a predetermined number of beacons and being allocated for processing a sub-message. Each beacon is associated with a specific occurrence of the sub-message. Learning includes splitting a message into B sub-messages to be learned, where B is greater than or equal to two; activating, for a sub-message, a single beacon in each block to be in the on state, all of the other beacons of the block being in the off state; and activating binary connections between the on beacons of each of the block for a message to be learned, which assume only connected and disconnected states.
Thomson Licensing and Telecom Bretagne | Date: 2010-11-17
A content distribution network has at least two network stations adapted for storing and retrieval of content. The content is divided in complementary fragments stored in different network stations. When a further network station is added to the network it determines which fragments of a desired content are available from other network stations within a predetermined maximum distance. In case not all fragments of the desired content are available within the predetermined distance the added network station downloads a random fragment from a set of missing fragments of the desired content from a network station that is further away than the predetermined distance. Otherwise the added network station determines a set of network stations located within the predetermined maximum distance having the closest distance to the added network station, while, in their totality, storing all fragments of the desired content required for producing the complete file. The added network station then downloads the fragment of the desired content from that network station out of the previously determined set of network stations that has the largest distance.
Telecom Bretagne | Date: 2014-09-19
The invention relates to a transition device between a printed transmission line on a dielectric substrate and a rectangular waveguide including a front face forming an inlet of the waveguide, a rear face parallel to the front face and forming an outlet of the waveguide, a lower face, an upper face parallel to the lower face, the upper and lower faces extending between the front and rear faces, the waveguide being a block of dielectric material whereof the faces are fully metalized except for the front face and the rear face, the transition device including:
Telecom Bretagne | Date: 2014-05-30
The invention relates to a compact multi-level antenna including: a ground plane; a radiating element including n2 portions extending in n2 parallel planes in a planar pattern, the planes defining a volume above the ground plane, the radiating element including a first end connected to the ground plane and a second end ending with an open circuit.
Telecom Bretagne | Date: 2010-01-29
A method is provided for encoding data to be sent to at least one receiver, including at least two identical encoding steps and at least one permutation step. Each encoding step associates a block of encoded data with a block of data to be encoded, using at least two basic codes, each code processing a subset of the data block to be encoded. The permutation step is inserted between two encoding steps, i.e. a current encoding step and a previous encoding step, such that the order of the data in a data block to be encoded by the current encoding step is different from the order of the data encoded by the previous encoding step. The permutation step implements, for a data block, a rotation applied to the data of the data block and a reversal of the order of the data of the data block. The operations can be implemented by an interleaving matrix.
Chinese Academy of Sciences and Telecom Bretagne | Date: 2012-06-27
An underwater timing and synchronizing method and system is provided, in which a server provides an accurate time reference, and a client realizes local clock calibration through information interaction with the server. Specifically, when requiring clock calibration, the client transmits a request signal to the server, and uses the transmission time as the start time of the timing process. After receiving the request signal, the server performs time reversing processing of the received signal to obtain a responsive signal and then sends the same back to the client; moreover, the accurate transmission time of the responsive signal is sent to the client by means of acoustic communication. Due to time reversal mirrors focusing features in time and space, all responsive signals are converged to the client, then the client convolutes the converged signal with the request signal to obtain a time reference signal, based on which the end time of the timing process is accurately determined, wherein the accurate transmission time of the responsive signal on the server is exactly the midpoint of the timing process.
Telecom Bretagne | Date: 2014-07-15
The invention relates to an antennal structure adapted to be disposed on an earth plane comprising: a three-dimensional support substrate made of a dielectric material which is partially hollowed out and comprising a peripheral wall which extends between a proximal end and a distal end, said support substrate defining an internal volume; a first conducting pattern inscribed on the peripheral wall of the support substrate, the first conducting pattern comprising a lower end adapted to be connected to an earth plane and an upper end; a second conducting pattern contained in the volume of the substrate, the second pattern being connected electrically to the upper end of the first pattern.