Matra

About: Matra is a based out in . It is known for research contribution in the topics: Signal & Detector. The organization has 1330 authors who have published 1216 publications receiving 17967 citations.

Design and critical technology breadboarding of a high-resolution thermal infrared radiometer (HRTIR)

Abstract: HRTIR for High Resolution Thermal Infrared Radiometer is an earth observation instrument candidate to the European Space Agency polar platform beyond Envisat 1. A preliminary design of the instrument has been performed in order to identify the most critical points and breadboard them. The instrument is a push broom concept providing an on ground spatial resolution of 50 m for a swath width of 50 km and a temperature sensitivity of 0.1 K in 3 spectral bands in the 8 to 12.5 micrometers range. A compact dioptric system has been selected for the optics and the focal plane consists of three linear arrays of 1000 HgCeTe photovoltaic elements hybridized on a CCD multiplexer and cooled down to 50 K inside a cryostat by mechanical cryocoolers. The HgCdTe IRCCD with a cut-off wavelength longer than 12.5 micrometers has been identified as the most critical technology and breadboarded. A complete detection chain with a long wavelength linear array of 222 pixels obtained by butting of three sub-arrays, a CCD multiplexer, a driving and processing electronics up to digital signal has been manufactured. The linear array is housed in a cryostat similar to the foreseen flight model but coupled to a laboratory cryogenic system. The IRCCD has been tested at unit level and the complete detection chain have been characterized in laboratory in conditions close to the flight. The test results have demonstrated the feasibility of the IRCCD at long wavelength with excellent performances. The instrument radiometric performances have been validated from the breadboard test results.

Slatted support base for a bed.

Abstract: of EP0344105The slatted support base for beds has a region in which the hardness can be adjusted. In this region, in which the hardness can be adjusted, counter-slats (4) are arranged with spacing below the resting surface for the mattress, which resting surface is defined by the sprung slats (3). Buffer elements (15, 19) are guided so as to be longitudinally displaceable through these counter-slats. These buffer elements serve for supporting the sprung slats situated above them. The sprung slats (3) are attached to the frame (2) of the slatted support base by a rubber elastic attachment element (5). Inserted between two such rubber elastic attachment elements (5) in each case is an attachment element (6) for the counter-slats. While the rubber elastic attachment element (5) is attached to the longitudinal side of the frame by two pins, the attachment element (6) does not need any further attachment to the frame (2). The slatted support base which can be adjusted in hardness allows simple adjustment and allows a good ventilation of the mattress in the zone in which the hardness can be adjusted. The attachment elements likewise allow refitting of a slatted support base with counter-slats and buffer elements without the use of tools and without knowledge of the craft.

Influence of cell structure on the SEU sensitivity of a SRAM

Abstract: We have experimentally studied the single event upset sensitivity of CMOS on an epilayer 64 Kbit SRAM test vehicle. The device cross sections have been measured using accelerator beams and we have investigated the influence of the memory cell structure on the asymptotic cross section. >

Complex Control Systems

Abstract: The digital computer made its appearance before the general public in the sixties when it was recognized as one of the enabling technologies of the Apollo program, culminating in the international emotions of man’s first steps on the moon. From this glorious start the imprint of computer technology on our day to day life has been steadily increasing, even if sometimes less conspicuously.

Design Of A Wavelength Division Multiplexing/Demultiplexing System For Optical Intersatellite Links

Abstract: Optical communications is an alternative to the microwave solution for high data rate interorbit (IOL) or intersatellite link (ISL), typically 500 Mbit/s.The optical system, using laser diode technology, only requires small size antennae, provided that multiplexing or power combining techniques are used.This paper presents a Wavelength Division Multiplexing/Demultiplexing System involving orthogonal polarizations for adjacent channels. This solution is preferred to the power combining technique to satisfy some specific system and interfaces constraints and to avoid a very accurate control of laser wavelength.The proposed design complies with system constraints like redundancy, minimum back­ light on the laser junction, interchannel interferences, depolarization in the optical system, compacity, ... Its simplicity -the required components are only A/4 plates, filters under normal incidence and polarizer beamsplitters- is attractive and the concept, descri­ bed here for 4 wavelengths in the 0.817-0.843 \i range, can be applied to an unlimited number of wavelengths. The computed performances in transmission and isolation taking into account all parasitic reflections are given.A breadboard model is currently under development at MATRA to be tested in 1987. Preliminary results of sub-assemblies tests are presented.IntroductionLaser diodes technology offers many advantages for intersatellite communications. However, its application to Data Relay Satellite, which is currently studied in Europel, must overcome power limitations to support the required high data rate around 500 Mbit/s. In fact, today available components exhibiting good quality beam are single longitudinal mode, index guided devices, whose reliable power is limited to about 50 mW. To circumvent this limitation, two methods can be envisaged :- power combining,- multiplexing/demultiplexing (or WDM)The first technique increases by different means ' the output power transmitted to a single APD-receiver, while WDM technique associates a receiver to each wavelength and then requires data channelization. This second approach has been selected for the future EDRS (European Data Relay Satellite).Selection of the WDM techniqueTaking into account the European Data Relay Satellite requirements, namely a great operational flexibility -particularly to transmit independant data from different payloads on the same satellite-and 120 Mbit/s channelization in the feeder link, the WDM technique is particularly suitable. To provide about 500 Mbit/s interorbit communications, a 4 channels system (each one with 120 Mbit/s) has been considered.MATRA studies have lead to a MUX/DEMUX concept which is the subject of a Patent appli­ cation.The functional block diagram is described in figure 1, where redundancies are implemen­ ted at component level (2 diodes per wavelength) as well as subsystem level (2 multiplexer assemblies) in view to satisfy the reliability requirements (0.9 for 5 years on LEO).Selected concept A. SpecificationsA.I Laser diodes available wavelengths : commercially available single mode diodes in the 0.8 |i region are double heterostructure GaAs/GaAlAs components. Their wavelength distribution looks like what is shown on figure 2. The available wavelength range is then limited to 815-845 nm.