ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Space Communications, Spacecraft Communications, Command and Tracking  (7)
  • Herkenning  (3)
  • 2000-2004  (10)
  • 1970-1974
  • 1
    facet.materialart.
    Unknown
    Optimizing Satellite Communications With Adaptive and Phased Array Antennas (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A new adaptive antenna array architecture for low-earth-orbiting satellite ground stations is being investigated. These ground stations are intended to have no moving parts and could potentially be operated in populated areas, where terrestrial interference is likely. The architecture includes multiple, moderately directive phased arrays. The phased arrays, each steered in the approximate direction of the satellite, are adaptively combined to enhance the Signal-to-Noise and Interference-Ratio (SNIR) of the desired satellite. The size of each phased array is to be traded-off with the number of phased arrays, to optimize cost, while meeting a bit-error-rate threshold. Also, two phased array architectures are being prototyped: a spacefed lens array and a reflect-array. If two co-channel satellites are in the field of view of the phased arrays, then multi-user detection techniques may enable simultaneous demodulation of the satellite signals, also known as Space Division Multiple Access (SDMA). We report on Phase I of the project, in which fixed directional elements are adaptively combined in a prototype to demodulate the S-band downlink of the EO-1 satellite, which is part of the New Millennium Program at NASA.
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: ESTC 2004; Jun 21, 2004 - Jun 23, 2004; Palo Alto, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Analysis and Optimization of Thin Film Ferroelectric Phase Shifters (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Microwave phase shifters have been fabricated from (YBa2Cu3O(7-delta) or Au)/SrTiO3 and Au/Ba(x)Sr(1-x)TiO3 films on LaAlO3 and MgO substrates. These coupled microstrip devices rival the performance of their semiconductor counter-parts parts at Ku- and K-band frequencies. Typical insertion loss for room temperature ferroelectric phase shifters at K-band is approximately equal 5 dB. An experimental and theoretical investigation of these novel devices explains the role of the ferroelectric film in overall device performance. A roadmap to the development of a 3 dB insertion loss phase shifter that would enable a new type of phased array antenna is discussed.
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: Materials Issues in Tunable RF and Microwave Devices; Nov 29, 1999 - Dec 03, 1999; Boston, MA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    The Case for Deep Space Telecommunications Relay Stations (2004)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: Each future mission to Jupiter and beyond must carry the traditional suite of telecommunications systems for command and control and for mission data transmission to earth. The telecommunications hardware includes the large antenna and the high-power transmitters that enable the communications link. Yet future spacecraft will be scaled down from the hallmark missions of Galileo and Cassini to Jupiter and Saturn, respectively. This implies that a higher percentage of the spacecraft weight and power must be dedicated to telecommunications system. The following analysis quantifies this impact to future missions and then explores the merits of an alternative approach using deep space relay stations for the link back to earth. It will be demonstrated that a telecommunications relay satellite would reduce S/C telecommunications weight and power sufficiently to add one to two more instruments.
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: NASA/CR-2004-213053 , E-14489
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Electrical Characterization of Polyaniline/polyethylene Oxide Nanofibers for Field Effect Transistors (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Nanofibers comprised of polyaniline/polyethylene oxide (PANI/PEO) are being developed for novel logic devices. We report the electrical conductivity of PANI/PEO nanofibers with diameters in the 100 to 200 nm range. We measured conductivity values of approx. 0.3 to 1.0 S/cm, which is higher than the values reported for thicker nanofibers, but less than the bulk value of PANI. The electrical measurements were performed by depositing the fibers on pre-electroded, oxidized silicon (Si) substrates. The excellent adherence of the nanofibers to the SiO2 as well as the gold (Au) electrodes may be useful in the design of future devices.
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: NASA/TM-2002-212016 , E-13707 , NAS 1.15:212016 , 2003 Nanotechnology Conference and Trade Show; Feb 23, 2003 - Feb 27, 2003; San Francisco, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Interplay Between Thin Film Ferroelectric Composition, Microstructure and Microwave Phase Shifter Performance (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: One of the keys to successfully incorporating ferroelectric films into Ku-band (12 to 18 GHz) phase shifters is to establish the composition, microstructure, and thickness required to meet the tuning needs, and tailor the film properties to meet these needs. Optimal performance is obtained when the film composition and device design are such that the device performance is limited by odd mode dielectric losses, and these losses are minimized as much as possible while still maintaining adequate tunability. The parameters required to maintain device performance will vary slightly depending on composition, but we can conclude that the best tuning-to-loss figures of merit (K-factor) are obtained when there is minimal variation between the in-plane and out-of-plane lattice parameters, and the full-width half maximum values of the BSTO (002) peaks are less than approximately 0.04 deg. We have observed that for phase shifters in which the ferroelectric crystalline quality and thickness are almost identical, higher losses are observed in films with higher BaISr ratios. The best performance was observed in phase shifters with Ba:Sr = 30:70. The superiority of this composition was attributed to several interacting factors: the B a: Sr ratio was such that the Curie temperature (180 K) was far removed from room temperature, the crystalline quality of the film was excellent, and there was virtually no difference between the inplane and out-of-plane lattice parameters of the film.
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: NASA/TM-2003-211987 , E-13426 , NAS 1.15:211987 , 13th International Symposium on Integrated Ferroelectrics; May 28, 2002 - Jun 01, 2002; Nara; Japan
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Linking Satellites Via Earth "Hot Spots" and the Internet to Form Ad Hoc Constellations (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: As more assets are placed in orbit, opportunities emerge to combine various sets of satellites in temporary constellations to perform collaborative image collections. Often, new operations concepts for a satellite or set of satellites emerge after launch. To the degree with which new space assets can be inexpensively and rapidly integrated into temporary or "ad hoc" constellations, will determine whether these new ideas will be implemented or not. On the Earth Observing 1 (EO-1) satellite, a New Millennium Program mission, a number of experiments were conducted and are being conducted to demonstrate various aspects of an architecture that, when taken as a whole, will enable progressive mission autonomy. In particular, the target architecture will use adaptive ground antenna arrays to form, as close as possible, the equivalent of wireless access points for low earth orbiting satellites. Coupled with various ground and flight software and the Internet. the architecture enables progressive mission autonomy. Thus, new collaborative sensing techniques can be implemented post-launch. This paper will outline the overall operations concept and highlight details of both the research effort being conducted in 〈he area of adaptive antenna arrays and some of the related successful autonomy software that has been implemented using EO-1 and other operational satellites. Keywords: collaborative remote sensing smart antennas, adaptive antenna arrays, sensor webs. ad hoc constellations, mission autonomy and
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: SPIE 2004; Nov 08, 2004 - Nov 12, 2004; Honolulu, HI; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Liquid Crystal-Based Beam Steering Device Development for NASA Applications (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Computing, Information and Communications Technology (CICT) Program is supporting the development of liquid crystal-based beam steering devices. The device would use inexpensive, light-weight, optical components, and it would have the following capabilities: electronic beam scanning to angles above 1 milliradian, and submicroradian beam pointing accuracy. In order to correct for the imperfections resulting from the space-deployable optics, the technique of wave-front correction would be implemented. Hence, the output beam quality would be maintained. The potential applications could include satellite tracking, near-Earth inter-satellite communications, deep-space communications, and optical phased array systems. The status of the beam steering device development based on the liquid crystal technology and its relationship to prospective NASA mission scenarios will be described.
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: Great Lakes Photonics Symposium; Jun 07, 2004 - Jun 11, 2004; Cleveland, OH; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Voelt de medicinale bloedzuiger Hirudo medicinalis zich wel zo lekker in Nederland (Hirudinea)? (2000)
    In:  Nederlandse Faunistische Mededelingen vol. 12, pp. 1-10
    Details
    Publication Date: 2024-01-12
    Description: Does the medicinal leech Hirudo medicinalis feel well in the Netherlands (Hirudinea)? \nThis paper provides information on the medicinal leech Hirudo medicinalis Linnaeus, 1758 particularly in The Netherlands. Although this species was common in The Netherlands in the 18th century, nowadays it is very rare. Most animals were found in waters on sandy soil (71%): dune pools (10%) and pleistocene sandy areas (61%), where it inhabits especially soft water moor and heathland pools. About 20% of the records originate from river areas, where the species can be found in breakthrough ponds and oxbow lakes. Only 9% of the records are from fen and clay areas. Records of single specimens are not proof of an established population, because these specimens could also have survived after dispersal by waterfowl. Ten populations are currently known in The Netherlands. The leech is an indicator of special conditions such as high temperatures (shallow water), aerobic soil (e.g. sand for egg development) as well as of high biodiversity (feeding on snails, fish, amphibians, water birds and mammals). The medicinal leech is therefore threatened in The Netherlands by acidification, eutrophication and desiccation of their typical water biotopes causing an elimination of their vital prey (snails, fish and amphibians). Also the changed land use in agriculture is not favourable for the medicinal leech. In the past there were many drinking pools for cattle; nowadays drinking pools are very scarce and replaced by automated drinking systems. Management to restore the typical biotopes of the medicinal leech will further favour the presence of a lot of other species considered important to nature conservancy.
    Keywords: Hirudinea ; Hirudo medicinalis ; Nederland ; Verspreiding ; Biotopen ; Biologie ; Herkenning
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 9
    facet.materialart.
    Unknown
    De eerste vondst van de lichtgroene sabelsprinkhaan Metrioptera bicolor in Nederland (Orthoptera: Tettigoniidae) (2004)
    In:  Nederlandse Faunistische Mededelingen vol. 21, pp. 7-10
    Details
    Publication Date: 2024-01-12
    Description: The two-coloured bush-cricket Metrioptera bicolor, first record for the Netherlands\n(Orthoptera: Tettigoniidae)\nThe first record of Metrioptera bicolor for the Netherlands is presented. A long winged male was\nfound singing in a chalk grassland with high vegetation in the Poppelmondedal on the Sint\nPietersberg (southernmost part of the province of Limburg). Recently the species has reached\nclose to the Dutch border in Belgium and Germany. The northward expansion of this highly\nxerothermophilic species is due to a period of warm summers on a row. Whether the species will\nsettle in the Netherlands depends on the climatic conditions.
    Keywords: Sprinkhanen ; Nederland ; Herkenning ; Verspreiding
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 10
    facet.materialart.
    Unknown
    Boomkrekels Oecanthus pellucens bij Lobith het land binnen (Orthoptera: Gryllidae) (2004)
    In:  Nederlandse Faunistische Mededelingen vol. 21, pp. 1-6
    Details
    Publication Date: 2024-01-12
    Description: Oecanthus pellucens entering the Netherlands at Lobith (Orthoptera: Gryllidae)\nOn august 8, 2004 a male Oecanthus pellucens was heard along the river Waal, just east of the\ncity of Nijmegen (the Netherlands). Additional searches revealed that the species is distributed\nfrom the German border towards Nijmegen and Arnhem along the rivers Waal and Rhine\nrespectively. These observations confirm that O. pellucens has successfully colonised the\nNetherlands in a natural way and has probably been present for several years. Previous records\nof O. pellucens in the Netherlands were attributed to transport by traffic from southern Europe.\nAll specimens were found along the shore of the river, indicating that dispersal is accomplished\nby water transport during winter and spring flooding. During this period the eggs of the species\nare in diapause inside plants. Since O. pellucens is very thermophilous it remains to be seen if it\ncan survive the next cold and wet summer.
    Keywords: Boomkrekel ; Nederland ; Verspreiding ; Herkenning
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...