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Anschutz H.,Norwegian Polar Institute | Anschutz H.,Norwegian Geotechnical Institute | Sinisalo A.,University of Oslo | Isaksson E.,Norwegian Polar Institute | And 7 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2011

Volcanic signatures in ice-core records provide an excellent means to date the cores and obtain information about accumulation rates. From several ice cores it is thus possible to extract a spatio-temporal accumulation pattern. We show records of electrical conductivity and sulfur from 13 firn cores from the Norwegian-USA scientific traverse during the International Polar Year 2007-2009 (IPY) through East Antarctica. Major volcanic eruptions are identified and used to assess century-scale accumulation changes. The largest changes seem to occur in the most recent decades with accumulation over the period 1963-2007/08 being up to 25% different from the long-term record. There is no clear overall trend, some sites show an increase in accumulation over the period 1963 to present while others show a decrease. Almost all of the sites above 3200 m above sea level (asl) suggest a decrease. These sites also show a significantly lower accumulation value than large-scale assessments both for the period 1963 to present and for the long-term mean at the respective drill sites. The spatial accumulation distribution is influenced mainly by elevation and distance to the ocean (continentality), as expected. Ground-penetrating radar data around the drill sites show a spatial variability within 10-20% over several tens of kilometers, indicating that our drill sites are well representative for the area around them. Our results are important for large-scale assessments of Antarctic mass balance and model validation. Copyright 2011 by the American Geophysical Union.


Solberg L.E.,University of Oslo | Hamran S.-E.,Forsvarets Forskningsinstitutt | Hamran S.-E.,University of Oslo | Berger T.,Forsvarets Forskningsinstitutt | And 2 more authors.
Eurasip Journal on Advances in Signal Processing | Year: 2010

This paper studies the optimum signal choice for the estimation of the aortic blood pressure via aorta radius, using a monostatic radar configuration. The method involves developing the Cramér-Rao lower bound (CRLB) for a simplified model. The CRLB for model parameters are compared with simulation results using a grid-based approach for estimation. The CRLBs are within the 99 confidence intervals for all chosen parameter values. The CRLBs show an optimal region within an ellipsoid centered at 1GHz center frequency and 1.25GHz bandwidth with axes of 0.5GHz and 1GHz, respectively. Calculations show that emitted signal energy to received noise spectral density should exceed 10 12 for a precision of approximately 0.1mm for a large range of model parameters. This implies a minimum average power of 0.4μW. These values are based on optimistic assumptions. Reflections, improved propagation model, true receiver noise, and parameter ranges should be considered in a practical implementation. Copyright © 2010 Lars Erik Solberg et al.


Ciarletti V.,French National Center for Scientific Research | Corbel C.,French National Center for Scientific Research | Plettemeier D.,TU Dresden | Cais P.,Laboratoire Dastronomie Of Bordeaux | And 2 more authors.
Proceedings of the IEEE | Year: 2011

The Water Ice Subsurface Deposit Observation on Mars (WISDOM) Ground Penetrating Radar (GPR) is one of the instruments that have been selected as part of the Pasteur payload of the European Space Agency's (ESA's) 2018 ExoMars Rover mission. The main scientific objectives of the mission are to search for evidence of past and present life and to characterize the nature of the shallow subsurface. The Rover is equipped with a drill that can sample the subsurface down to a depth of approximately 2 m. The WISDOM GPR is the only instrumentation capable of obtaining information about the nature of the subsurface along the Rover path before drilling. WISDOM has been designed to explore the first ∼3 m of the subsurface with a vertical resolution of a few centimeters. The paper presents a description of the WISDOM instrument with a particular emphasis on the electronic architecture and antenna design that have been chosen to meet the challenging technical objectives. Some preliminary measurements obtained with the prototype are given to illustrate the instrument's potential performance. © 2010 IEEE.


Nesser P.,Forsvarets forskningsinstitutt
Terrorism and Political Violence | Year: 2011

The article explores ideological fault lines among Sunni Muslim militants (jihadists) in Europe since the mid-1990s. It argues there have been disputes among the militants about whether to prioritize local struggles or Al Qaeda's global war, and about the legitimacy of launching terrorist attacks in European states offering political asylum to Muslims. It concludes that Europe's militants have become more ideologically unified in conjunction with the invasions of Afghanistan, Iraq, and the Mohammed drawings, seeing European countries as legitimate and prioritized targets, and identifying with Al Qaeda. © Taylor & Francis Group, LLC.


Beattie A.M.,University of Toronto | Helleren O.,Forsvarets Forskningsinstitutt | Zee R.E.,University of Toronto
Proceedings of the International Astronautical Congress, IAC | Year: 2013

The Space Flight Laboratory (SFL) at the University of Toronto Institute for Aerospace Studies (UTIAS) in Toronto, Canada has been a pioneer in nano- and microsatellite technologies since the launch of its first satellites in 2003. Since then, UTIAS/SFL has launched five more nanosatellites, ranging in size from 3 to 7 kg and spanning several different generations of technology and mission profiles. This makes UTIAS/SFL one of the largest and most experienced nanosatellite builders and operators in the world. The Automatic Identification System Satellite no. 1 (AISSat-1) was launched on July 12, 2010 into a 635 km sun synchronous orbit by an Indian PSLV rocket from Satish Dhawan Space Centre in Andhra Pradesh, India. AISSat-1 is a six kilogram nanosatellite based on the Generic Nanosatellite Bus (GNB) satellite platform, and was designed, built, and commissioned in orbit by UTIAS/SFL The second satellite in this series, AISSat-2, has been completed and will be launched in 2013. The third satellite, AISSat-3, is under construction and will be launched in late 2014 or early 2015. The primary mission of the AlSSat-series of satellites is to receive maritime Automatic Identification System (AIS) message traffic within the primary observational area over Norwegian territorial waters, especially in the High North. Each satellite operates at a high duty cycle, with most of the coverage area revisited every orbit. Data is received, decoded, downloaded, and distributed into the Norwegian Coastal Authority's live ground network to end users in real time. The program is funded by the Norwegian Space Centre, and managed and operated by the Norwegian Defence Research Establishment (FFI). The AlSSat constellation provides a high degree of observational and monitoring capability assurance to the Norwegian maritime authority. Using a highly capable nanosatellite platform, this has been achieved at very low cost relative to other approaches to such a capability. This paper will discuss the in-flight operational experience and performance of the AISSat-1 satellite, and the combined constellation of all three satellites. In particular, the observational availability of the system based on in-flight experience will be highlighted. ©2013 by the International Astronautical Federation. All rights reserved.


Beattie A.M.,University of Toronto | Narheim B.T.,Forsvarets Forskningsinstitutt | Helleren O.,Forsvarets Forskningsinstitutt | Zee R.E.,University of Toronto
30th AIAA International Communications Satellite System Conference (ICSSC), 2012 | Year: 2012

The Automatic Identification System Satellite no. 1 (AISSat-1) was launched on July 12, 2010 into a 635 km sun synchronous orbit by an Indian rocket from the Satish Dhawan Space Centre in Andhra Pradesh, India. AISSat-1 is a six kilogram nanosatellite based on the Generic Nanosatellite Bus (GNB) satellite platform, and was designed, built, and commissioned in orbit by the University of Toronto Institute for Aerospace Studies, Space Flight Laboratory (UTIAS/SFL). The second satellite in this series, AISSat-2, is slated for launch in 2013. The primary mission of the AISSat-1&2 satellites is the reception and reporting of maritime Automatic Identification System (AIS) message traffic within the primary observational area over Norwegian territorial waters, especially in the High North. Each satellite operates at a high duty cycle, with most of the coverage area revisited every orbit. Data is received, decoded, downloaded, and distributed into the Norwegian Coastal Administration’s live ground network to end users in real time. The program is funded by the Norwegian Space Centre, and managed and operated by the Norwegian Defence Research Establishment (FFI). AISSat-2’s primary purpose is to provide an on-orbit spare capability to maintain the basic AIS observation capability past the end of design-life of the first satellite. The combined mission will provide additional availability assurances of the operational maritime observation capability to Norwegian authorities. Using a highly capable nanosatellite platform, this has been achieved at very low cost relative to other approaches to such a capability. This paper will discuss the GNB nanosatellite platform, its implementation in the Norwegian space-based AIS missions, and the combined observational system. © 2012 by the authors. Published by FGM Events LLC and distributed by AIAA with permission. All other rights reserved.


Patent
Forsvarets Forskningsinstitutt | Date: 2014-03-13

An imager contains an image sensor with laterally varying spectral response. The imager is scanned over a scene or object to form a spectral image. The spectral responses are repeated at different positions in the field of view so as to reduce the effect of scene nonidealities, such as angle dependence or temporal variation, on the spectral image data. A part of the image sensor may be used for conventional two-dimensional imaging. This part of the image sensor may be used to estimate the scene geometry and scan movement, enabling further improvement in the spectral integrity.


Patent
Forsvarets Forskningsinstitutt | Date: 2012-07-11

Method for collecting information from other radio transmitters and/or receivers for the purpose of coordinating and controlling the interference between transmitters and receivers. The method comprises discovering other radio transmitters and receivers in a network. Peer-to-peer communication is used over the Internet when determining relevant neighboring nodes for own communication and performing resource management for the set of radio transmitters and receivers.


Patent
Forsvarets Forskningsinstitutt | Date: 2014-01-15

Method for collecting information from other radio transmitters and/or receivers for the purpose of coordinating and controlling the interference between transmitters and receivers. The method comprises discovering other radio transmitters and receivers in a network. Peer-to-peer communication is used over the Internet when determining relevant neighbouring nodes for own communication and performing resource management for the set of radio transmitters and receivers.


PubMed | Forsvarets Forskningsinstitutt
Type: Comparative Study | Journal: The Journal of the Acoustical Society of America | Year: 2011

Underwater communication experiments have been conducted in the Norwegian Oslofjord. Two modulation schemes are compared in a 7-kHz frequency band on a 14-kHz center frequency. The first scheme is direct-sequence spread spectrum (DSSS), using a 7-chip spreading code to achieve a raw data rate of 1000 bps on a single carrier. The second scheme is multicarrier spread spectrum (MCSS) and accomplishes spreading by using seven subbands. The DSSS receiver equalizes on the chips prior to explicit symbol despreading, whereas MCSS features joint multiband equalization and despreading. Four channels are examined, from nearly static to overspread. In slowly varying channels, MCSS offers the best performance. DSSS has the best tracking potential for rapidly varying channels, where the challenge is to obtain reliable chip decisions before symbol despreading. The tracking potential can be realized to some extent by hypothesis-feedback equalization. It is further shown that adaptive equalizers are capable of code conversion, i.e., the DSSS receiver can demodulate the MCSS waveform, and vice versa. Neither receiver requires knowledge of the spreading code in order to despread the data.

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