Abstract:
The invention concerns a system and process for sending secure faxes that include a sending fax machine (20); a receiving fax machine (23); and a registered fax server (21). One of the fax machines is provided with a security module that assures document integrity, produces and verifies digital signatures and combats replays.
Abstract:
The invention provides a method of verifying the integrity of sequences of data transmitted from a first station to a second station in a broadcast network during a call set up between the first and second stations. First and second encipherment seals are calculated in a control station separate from and independent of the first and second stations, respectively in response to reception of a sequence corresponding to the transmitted data sequence and in response to reception of the sequence which is received in and retransmitted by the second station. A comparison of the calculated seals for integrity verification is preceded in the control station by searching for the first seal calculated according to an identification word of the sequence which is retransmitted by the second station. The invention relates to a method of verifying the integrity of data sequences exchanged between stations respectively belonging to different broadcast networks.
Abstract:
The light pulse generator includes a source for generating a light beam, an electroabsorbent modulator for modulating the light beam into light pulses, and means for applying voltage control to the modulator. The electroabsorbent modulator includes at least two doped layers and between them at least one intermediate layer that is made of a material that is not intentionally doped, and that has an electroabsorbent material included therein. The absorbent or transparent state of the intermediate layer is controlled by a voltage applied between two of the doped layers that have doping of the same sign, the transmissivity of the modulator as a function of the voltage controlling it being at a maximum in the vicinity of zero volts and being symmetrical thereabout.
Abstract:
An interface device between a public telephone (9) and an external terminal (14), the public telephone (9) having a control circuit (10) connected to a telephone line (20) and the interface device having a connector (15) accessible to the user. A switching circuit (22) makes it possible to switch the line (20) either to the control circuit of the public telephone (10), or to a connector control circuit. An information circuit of a connection of the external terminal is in the connector, a first electrical insulation module (21) is located between a connector control circuit and the switching circuit (22), a second electrical insulation module (19) is between a connector control circuit and the control circuit of the public telephone (9) and a control circuit of the connector (16).
Abstract:
A vertical emission laser structure comprising an active region between stacks of layers forming Bragg reflection mirrors respectively of the n-type and of the p-type, wherein: the stacks of layers are formed by different pairs of materials in the n-type mirror and in the p-type mirror; the pair of materials constituting the n-type mirror comprises materials having a conduction band gap that is narrow or even non-existent; and the pair of materials constituting the p-type mirror comprises materials having a valance band gap that is narrow, or even non-existent.
Abstract:
A tree-structured star telecommunication network of the wavelength division multiplex transmission type includes multirate periodic downstream and upstream frames transmitted at different wavelengths in full-duplex mode, thereby to connect a central terminal with a plurality of user terminals. Half-duplex transmission for each low bit rate terminal equipment uses a half-frame period shift with respect to the frame period between upstream frame data sectors and downstream frame data sectors. Data derive by the high rate equipment is transmitted in upstream and downstream sectors not occupied by low bit rate data.
Abstract:
A process and device for the analog convolution of images, especially two-dimensional convolution operations of Gaussian type on a set of image pixels represented by voltages. The voltages are applied to a first set of capacitors. For each capacitor, one terminal is connected to a reference voltage; the other terminal is part of a network of nodes, each of which is insulated from the others. The nodes which are adjacent are connected together for a predetermined duration via a second set of uncharged capacitors. The nodes of the network are then insulated from each other again and the second set of capacitors are discharged. The steps of connecting the nodes together, insulating them from each other, and discharging the second set are repeated. Finally, the new voltages on the nodes of the network, which represent the pixels of a convolved image, are read out.
Abstract:
An add-drop multiplexer includes a first photodector (14), which receives informations in optical form, some of which are to be supplied to users addressees or recipients chosen from among N users addressees or recipients associated with the wavelengths L1, . . . , LN, whilst the other informations form an output flow at wavelength LO, a second photodetector (16) receiving in optical form informations to be inserted in said flow, a tunable source (18), which converts the signals from the first photodetector into optical signals of wavelengths chosen from among LO, L1 . . . LN under the control of control unit (20) and as a function of their destination, another source (22), which converts the signals from the second photodetector into optical signals of wavelength LO, a coupler (24) connecting the sources to N+1 filters (f0 . . . , f3) only respectively permitting the passage of LO . . . LN. Application to optical telecommunications.
Abstract:
An interferometric system for sensing and locating reflective defects in light-conducting structures comprises a mono-mode laser source (6), an incoherent source (4) with substantially the same central wavelength as the laser source, first and second couplers (10, 20) connected to the sources and to light sensors (52, 54), a first support (36) movable in one direction (D) and connected to the ends of the first and second couplers, a second support (38) oscillating in the same direction (D), reflectors (42, 43) attached to the second support opposite the ends of the first and second couplers. A third support support (40) is movable in the same direction (D) and connected to one end of the second coupler (20), a further stationary reflector (48) opposite said end, of the second coupler. The first coupler is connected to an optical waveguide (2), and devices (56, 58) for locating reflective defects in the waveguide.
Abstract:
A multiplier of order p and of depth n+1 is formed by a root R constituted by a carry-save adder and by a multiplier body CO(p,n) of order p and of depth n formed by a five-input connector operator C(n,q) of rank q, the connector operator C(n,1) of rank 1 is connected to the root R, the connector operator C(n,q) of rank q comprising first and second carry-save adders (1, 2) connected in cascade. The multiplier body CO(p,n) further includes a tree A(p-1,n-2) of order p-1 and of depth n-2 formed by an arrangement of carry-save adders and connected to the first carry-save adder (1), and a multiplier body CO(p,n-1 ) of order p and of lesser depth n-1 formed analogously to the multiplier body CO(p,n) of greater depth n by recurrence, the multiplier body CO(p,n-1) of lesser depth being connected to the connector operator C(n,q). The multiplier is applicable to performing calculations and to implementing digital filters.