Entrée : NAOMI - montrer la version 3
URI: https://terra-vocabulary.org/ncl/FAIR-Incubator/earthsciencesensors/c_3acf737c
NAOMI is a product line of high-resolution imagers designed and developed at EADS Astrium SAS. Several versions of the NAOMI instrument have already been developed with a GSD from 1.5 m to 2.5 m, and swath widths from 10 km up to 60 km. All of them are based on the same telescope concept implementing one or several focal planes units in the same camera, and even two cameras in the same instrument as for the SPOT-6 & SPOT-7 program. NAOMI instruments can be embarked on small platforms (Myriade class) or larger platforms (Astrosat-250). The IEU (Instrument Electronics Unit) can accommodate internal mass memory functions or can be coupled with high capacities mass memories like CORECI equipment also developed by Astrium SAS. The main building blocks of the instrument are: • A highly stable, light and compact telescope built in SiC material, with a simple thermal control. • A focal plane, embedding TDI (Time Delay Integration) detector, a PAN CCD and four XS (multispectral) detectors equipped with strip filters and coupled with front end electronics. The TDI implementation exhibits an outstanding MTF (Modulation Transfer Function) servicewith an extremely low power consumption. This allows significantly loosening of optical requirements at the telescope level, while keeping the same overall optical quality at system level; in other words, the same optical quality can be reached from smaller and much lighter telescopes. Therefore more performance can be obtained from smaller satellites. • Back-end electronics, including video Electronics, data storage and services adapted to the mission specificities. The modular video chains are capable of operating at different frequencies up to 15 Msample/s, so that the same hardware can be easily tuned to serve ground resolutions ranging from 0.5 m to say 10 m. The swath width can easily be adjusted by butting together several detectors and associated modular video chains, thus fulfilling the requirements of the most demanding customers. The telescope is based on a Korsch combination, offering a simple, compact concept. The detector, space qualified, includes on the same die one TDI matrix of 7000 pixels for the panchromatic channel, and four lines of 1750 pixels for the multispectral bands. The detector exhibits excellent characteristics that significantly contribute to the instrument very high optical performance. The optical assembly is based on a Korsch-type telescope including three aspheric mirrors and two folding mirrors. The detection chain is made of three main parts: the detectors, the Front End Electronics Module (F2EM) and the Video Electronics (MEV) which are part of the IEU (Imaging and Electronics Unit). The PAN + XS focal planes are the heart of the detection chain. Focal plane is based on a customized high performance detector architecture developed by e2v for Astrium (proprietary architecture). It takes benefit of all the heritage and skills acquired in CCD architecture definition and in operating with the ultimate conditions of speed and performances. The result of this customization offers an unrivalled level of integration and performances. All the stringent constraints of dynamic range optimization and power consumption reduction have been mastered with less than 1 watt detector dissipation. The Front-End Electronics Module (F2EM) encompasses all the functions to be implemented close to the detectors. Mounted inside the FPA (Focal Plane Assembly), it provides the detectors with all the necessary biasing and clocking signals and performs preamplification and transmission of the video signal to the MEV. The MEV (Module Electronique Video) is the backend part of the NAOMI detection electronics. The MEV provides the F2EM with the primary power supplies and clocks necessary to front-end operation. The video signal from the F2EM is received, adapted and digitally converted to 12 bit in the MEV. The resulting data, rounded down to 10 useful bit, are then transmitted to the digital functions of the NIEU to be real-time processed and stored into the mass memory for further downlink. Instrument type Pushbroom imager Optics - Korsch telescope in SiC (Silicon Carbide) - aperture diameter = 200 mm Spectral band (Pan) 0.45-0.75 µm MS (Multispectral bands), 4 Blue: 0.45-0.52 µm Green: 0.53-060 µm Red: 0.62-0.69 µm NIR: 0.76-0.89 µm The multispectral bands can be matched to suit customer needs GSD (Ground Sample Distance) PAN: from 1.5 m to 2.5 m at nadir MS: from 6 m to 10 m at nadir Detectors N x silicon area arrays with 7000 pixels PAN, 1750 pixels in each MS band TDI (Time Delay Integration) The PAN band offers TDI services for SNR improvement of the signal Swath width - From 10 km to 60 km at nadir depending on GSD and number of detectors 29) FOR (Field of Regard) ±30º (spacecraft tilting capability about nadir for event monitoring) Data quantization (dynamic range) 12 bit.