Abstract: Digital signal processing apparatus for frequency demultiplexing a wide band channel which converts the data stream into parallel branches by means of serial-to-parallel conversion, and demultiplexing which consists of low pass and high pass fine filtering stages and a coarse filtering stage split among processors across parallel branches. Wideband signals arc processed without expensive processors because of the slower rate in the parallel channels. This may also be used for the inverse function of multiplexing.

Abstract: A reception signal is input to an echo generator system. An observation signal is gathered from the system. The reception signal is filtered to produce an echo prediction signal. The echo prediction signal is subtracted from the observation signal to produce an error signal. The observation signal is decomposed into M spectral components relating to different frequencies of the spectrum. M corresponding spectral components of the echo prediction signal are obtained. M quantities, each having a value with progressive variation representative of a degree of similitude between, respectively, one of the M spectral components of the observation signal and the corresponding spectral component of the echo prediction signal, are calculated. At least one spectral shaping of the error signal is carried out as a function of these M calculated quantities so as to adapt the filtering and/or to deliver the output signal from the echo canceller.

Abstract: The CCD device is suitable for use in a lidar. It has an image zone constituted by a matrix of M lines and N columns of photosensitive sites for receiving a light signal and generating charges, a first memory zone constituted by a matrix of P lines and N columns of non-photosensitive sites, a read-out register having a single line of N sites, and a second memory zone having P lines of N sites, apt to receive in parallel charges contained in the N sites of the read-out register. The first memory zone has a first line of sites apt to receive and to sum charges generated in a respective column of the image zone at the end of each of successive acquisition periods. The second memory zone stores and transfers charges to N sites of a same line of the image zone or the first memory zone whereby accumulating, in each line of the first memory zone, charges accumulated during an observation period and resulting from a plurality of successive summations.

Abstract: The equipment comprises a radio terminal adapted to calls with a public mobile telephony network supporting voice transmission channels and data channels, and an extension unit which can be connected to a data interface of the terminal and allowing calls on the data channels of the network. This extension unit comprises a microphone, an earphone, a vocoder and a ciphering module. It has the same external appearance as a conventional mobile radio terminal. In a security call mode, the signal coming from the microphone of the extension unit is processed by the vocoder and then by the ciphering module in order to produce data sent to the data interface of the terminal, and the data received from the data interface of the terminal are processed by the ciphering module and by the vocoder in order to control the earphone of the extension unit.

Abstract: Switching means of a satellite has a first set of switches for receiving respective channel slots of de-multiplexed narrow band channels. The set of switches may be made up of four position switches 5.sup.1, 5.sup.2 etc. Switch 5.sup.2 may be connected straight through, or to the straight through positions of switches 5.sup.1 and or 5.sup.3 via interswitch connections. The same is possible with the second set of switches 6. A wide selection of the possible frequency slots is possible (for example eight out of sixteen) to allow routing among the amplifiers 9, 10, some of which are designated as redundant.

Abstract: A spacecraft platform essentially having two or more panels hinged at the base and contained for launch in a fairing. The panels are hinged and latched in an open deployment and bear, for example, a SAR antenna or an interferometer. The rear faces of the panels are provided with stiffening ribs, webs and struts and carry elements of the payload module and service module which are normally separate structures on a conventional satellite.

Abstract: An earth orbiting satellite is enabled to assume a "survival mode" of operation in which its x axis is aligned with the sun by observing characteristics of the movement of the frame of the satellite (e.g. its x axis) relative to the sun and performing calculations based on those operations. A more accurate result is achieved if a deliberate offset is introduced between the mean direction of the x axis and the sun's direction. The control arrangement for positioning the x axis with this offset is preferably adaptive, resulting in control of the satellite's thrusters so as to produce oscillation of the x axis in a way which allows suitable measurements to be taken.

Abstract: The transmission system is designed for links between an infrastructure and moving bodies (10.sub.1, 10.sub.2) constrained to move along a determined path. The infrastructure has fixed transmitter/receiver stations distributed along the path, each having two transmitter/receivers allocated to two adjacent cells, e.g. (E'.sub.1, E.sub.2). The transmitters of two successive fixed stations allocated to the same cell are synchronized and they transmit using a coding system that is capable of tolerating or taking advantage of propagation over multiple paths.

Abstract: A rotary actuator includes a bar made of shape memory alloy having ends provided with thermally insulating interface elements for interfacing with elements that are to be rotated relative to each other. An electric heater surrounds the bar and is apt to heat it above its transition temperature to the austenitic domain. The actuator is suitable for deploying or rotating solar panels.

Abstract: A method comprising the steps of performing a linear prediction analysis of a speech signal digitized in a series of frames divided into sub-frames, in order to determine the parameters of a short-term synthesis filter; carrying out an open loop analysis to detect voiced signal frames and determine, for each voice frame, a degree of signal voicing and a long-term prediction delay search interval containing a number of delays depending on the degree of voicing; carrying out a closed-loop predictive analysis of the speech signal to select, for at least some sub-frames of the voiced frames, a long-term prediction delay contained in the search interval and constituting a long-term synthesis filter parameter; and determining a stochastic excitation for each sub-frame, to minimize a perceptually weighted deviation between the speech signal and the stochastic excitation filtered by the long-term and short-term synthesis filters.

Abstract: A linear prediction analysis is performed for each frame of a speech signal to determine the coefficients of a short-term synthesis filter and an open-loop analysis is performed to determine a degree of frame voicing. At least one closed-loop analysis is performed for each sub-frame to determine an excitation sequence which, when applied to the short-term synthesis filter, generates a synthetic signal representative of the speech signal. Each closed-loop analysis uses the impulse response of a filter consisting of the short-term synthesis filter and a perceptual weighting filter, by truncating the impulse response to a truncation length that is no greater than the number of samples per sub-frame and is dependent on the energy distribution of the response and the degree of voicing of the frame.

Abstract: A switching circuit (3) having a low component count and suitable for use with a nuclear event detector circuit (2) provides a means for isolating a power source (1) from a load (2, 4). A bipolar transistor (5) provides a temperature insensitive, low voltage drop supply to the load (2, 4) and a MOSFET (7) provides base current to the bipolar transistor during standby mode; the MOSFET being turned on by the supply (1). When the supply voltage drops below the threshold voltage of the MOSFET (7), the base bias to the bipolar transistor (5) is removed. The bipolar transistor (5) cannot therefore conduct in the reverse sense and the circuit provides true isolation for the power supply (1) and the load (2, 4).

Abstract: A method and apparatus compare a star to be identified within an image with data in a database generated from known star data. According to a first aspect of the invention, a target star to be identified within an image is selected, and a number of adjacent stars, normally two, are also selected. The separation values between the stars and a geometric identity for each separation value are determined. This data is compared with corresponding data stored in a database for known stars, where the data in the database is generated using the same technique. According to a second aspect of the invention, a target star is selected, and adjacent stars are selected from an annulus centered on the target star. The separation values for the stars are determined and compared with known separation values stored in a database, where the data in the database is generated using the same annulus centered on each known target star.

Abstract: A multiplexer comprises a number of directional filters 17.sub.n connected to a transmission line feeding an antenna 2, 3. Signals to be multiplexed fed to the filters 17.sub.n may be sent via respective switches 16.sub.n. Unlike prior multiplexers where each directional filter defines a respective channel of the multiplex, the channels of the multiplexer of the invention, apart from one at the end, are defined by the band pass response of one directional filter and the band stop response of another directional filter, since the band pass responses of the directional filters from the input connected to the switch to the output connected to the transmission line, and the corresponding band stop responses between the two output ports connected to the transmission line, overlap each other. The same arrangement may be used for demultiplexing.

Abstract: A combined duplexer/mixer (2) for use with FMCW radar systems has a waveguide section (12,13) containing a fin-line structure (17,18) for responding to the linearly polarized radar return signal while permitting passage of the orthogonally polarized transmitted signal (T). A portion of the transmitted signal is extracted by a patch antenna (22), this extracted signal forming a local oscillator signal for mixing with the return.

Abstract: A receiving device performs N separate demodulations (N.gtoreq.2) each supplying respective estimates of successive binary symbols resulting from differential coding of a sequence of bits sent by a transmitting device, the differential coding being of the form a.sub.k c.sub.k .sym.a.sub.f(k) where a.sub.k and c.sub.k designate the binary symbol at position k and the bit at position k, f(k) designates an integer equal to k-1 at most and .sym. designates the exclusive-OR operation. Each estimate of a binary symbol at position k is a real number s.sub.k.sup.(i) (1=i=N) the sign of which represents the most probable value of the symbol and the modulus of which measures the likelihood of the most probable value.

Abstract: In order to correct nonlinearities of an amplifier which receives a radio signal and produces an amplified radio signal representing an input complex digital signal, a predistortion table, associating a value of a predistorted complex digital signal with each value of the input complex digital signal, is stored, and the predistorted complex signal is modulated in order to obtain the radio signal addressed to the amplifier. In an adaptation period, a fraction of the amplified radio signal is demodulated in order to obtain a demodulated complex signal which is compared with the input complex signal, with which the predistorted complex signal modulated in said adaptation period is associated, in order to update the predistortion table. The input complex signal or the predistorted complex signal has a phase which is constant modulo .pi. in the adaptation period.

Abstract: In order to correct nonlinearities of an amplifier which receives a radio signal and produces an amplified radio signal representing an input complex digital signal, a predistortion table, associating a value of a predistorted complex digital signal with each value of the input complex digital signal, is stored, and the predistorted complex signal is modulated in order to obtain the radio signal addressed to the amplifier. In an adaptation period, a fraction of the amplified radio signal is demodulated in order to obtain a demodulated complex signal which is compared with the input complex signal, with which the predistorted complex signal modulated in said adaptation period is associated, in order to update the predistortion table. The predistortion table is updated on the basis of mean values calculated from blocks of samples of the input complex signal and of the demodulated complex signal, which are stored in the adaptation period.