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    Adaptive fuzzy predictive tracking of feed supporting system for the square kilometre array

    Su, Y.X. ; Duan, B.Y. ; Peng, B. ; Nan, R.D.
    Intelligent Control and Automation, 2002. Proceedings of the 4th World Congress on

    Volume: 4
    DOI: 10.1109/WCICA.2002.1020147
    Publication Year: 2002 , Page(s): 3314 - 3318 vol.4
    Cited by:  Papers (1)

    IEEE Conference Publications

    In view of the characteristics of time-varying and large delay constant of cable-feed supporting system for next generation large radio telescope-Square Kilometer Array (SKA), the decentralized control strategy and an adaptive fuzzy predictive controller (AFPC) are proposed to realize the feed coarse tracking. The AFPC consists of a fuzzy predictor and a fuzzy predictive controller, and the on-line correction of which is carried out using BP algorithm. The simulation results have shown that the tracking precision is much favorable to guarantee the coarse tracking precision requirement, which have laid a solid base for the engineering implementation of the high precision requirement of the feed tracking control for the SKA. View full abstract»

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    The discovery of terrestrial, swept-frequency emission that mimics an interstellar dispersive delay

    Burke-Spolaor, S. ; Ekers, R.
    General Assembly and Scientific Symposium, 2011 XXXth URSI

    DOI: 10.1109/URSIGASS.2011.6051299
    Publication Year: 2011 , Page(s): 1 - 4

    IEEE Conference Publications

    We will detail the discovery of an anomalous terrestrial source of pulsed emission which exhibits a frequency-swept signal that closely mimics the frequency-dependent delay induced by dispersion in interstellar plasma. The signals were detected through the far sidelobes of Parkes Radio Telescope, appearing in all of the 13 independently-positioned receivers installed at the dish focus. The frequency-dependent delay and the sweep rates for most of the bursts are similar to those of a burst previously purported to be extragalactic. These bursts both call into question the extragalactic nature of that burst, and highlight the limitations of performing searches for one-off impulses with single dishes, in that they experience ambiguity in the positional localization of burst origins. View full abstract»

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    Measurement of analog fiber-optic link for broadband microwave signal transmission

    Na Fei Wu ; Qing Yuan Fan ; Bin Li
    Microwave Technology & Computational Electromagnetics (ICMTCE), 2011 IEEE International Conference on

    DOI: 10.1109/ICMTCE.2011.5915200
    Publication Year: 2011 , Page(s): 51 - 54

    IEEE Conference Publications

    The analog fiber-optic link for Shanghai 65m radio telescope comprise PSI-1602 broadband microwave photonic link and 500 meters Corning optical cable. Performance measurement of the analog fiber-optic link is discussed. First, explained the measurement principles and methods of the PSI-1602 broadband microwave photonic link. Then, elaborated the group delay temperature coefficient measurement of Corning smf28e optical fiber. At last, the measurement results of the analog fiber-optic link are given and discussed. The measured data of optical fiber temperature coefficient show that for temperature higher than 20°C, the group delay of the optical fiber varies within 10.3 ppm·°C-1 on average, 20°C lower, it varies within 36.3 ppm·°C-1 on average, which is more significant than higher temperature. View full abstract»

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    A 200-300 GHz single sideband SIS mixer for radio astronomy

    Karpov, A. ; Blondel, J. ; Billon-Pierron, D. ; Gundlach, K.-H.
    Applied Superconductivity, IEEE Transactions on

    Volume: 11 , Issue: 1 , Part: 1
    DOI: 10.1109/77.919476
    Publication Year: 2001 , Page(s): 844 - 847
    Cited by:  Papers (1)

    IEEE Journals & Magazines

    We present an ultra broadband low noise single sideband (SSB) SIS mixer developed for 200-300 GHz radio astronomy receivers. The mixer uses two Nb/AlOx/Nb junctions. Image band rejection by 20 dB is provided in the entire 200-300 GHz band using a mechanical tuning of the single noncontacting backshort in the mixer. The SIS receiver SSB noise temperature is close to 50 K in the main part of the band. A speed-up of the observations at radio telescopes by a factor 2-3 is expected with the new receiver View full abstract»

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    Software design for automatic changing feeds control system and video surveillance

    Yongjiang Li ; Yusup, A. ; Zengwu Sun ; Shaoguang Guo
    Software Engineering and Service Science (ICSESS), 2011 IEEE 2nd International Conference on

    DOI: 10.1109/ICSESS.2011.5982331
    Publication Year: 2011 , Page(s): 377 - 380

    IEEE Conference Publications

    This paper describes a 25m large-scale radio telescope's automatic control system of changing feeds. The software enables a good man-machine interface for automatic changing feeds instead of artificial changing feeds, which saves us a lot of time for changing feed and improves work efficiency. This system has achieved remote control of equipment house, accurate location quickly, real-time collecting data. Through the cameras installed in equipment house and we can view the lifting and dropping state of the feed and achieve the automatic real-time monitoring for changing feeds. View full abstract»

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    Activities for the square kilometer array (SKA) in Europe

    Ivashina, M.V. ; Van Ardenne, A. ; Bregman, J.D. ; de Vaate, J.G.B. ; van Veelen, M.
    Antenna Theory and Techniques, 2003. 4th International Conference on

    Volume: 2
    DOI: 10.1109/ICATT.2003.1238822
    Publication Year: 2003 , Page(s): 633 - 636 vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    The paper is an overview of the activities in research and development of the new generation radio telescope, the SKA, in Europe. It focuses on the aperture array technology for decameter and longer wavelengths, including relevant actions for the low frequency array (LOFAR) and focal plane arrays (FARADAY) covering the lower and higher frequency bands. We describe the concepts, specifications and the key parameters as well as application directions for radioastronomy for SKA, FARADAY and LOFAR. View full abstract»

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    Broadband dual polarised planar aperture arrays for wide field of view applications

    Brown, A.K. ; Yongwei Zhang
    Antennas and Propagation (EUCAP), 2012 6th European Conference on

    DOI: 10.1109/EuCAP.2012.6206688
    Publication Year: 2012 , Page(s): 643 - 646
    Cited by:  Papers (1)

    IEEE Conference Publications

    The Square Kilometre Array development demands a radio telescope with a high sensitivity, dual polarization and wide field of view over a broad bandwidth to meet the scientific goals. This paper describes a recently developed compact planar aperture array named Octagonal Ring Antenna (ORA). The ORA represents a novel and potentially breakthrough technology using a planar, easily fabricated, structure. It is expressly designed to be a low cost, low loss, wideband array. Based on initial large scale finite array studies prototypes with different geometries have been fabricated and measured. The characteristics and advantages of ORA over other conventional array antenna structures are discussed. The robustness of ORA is investigated in the applications where low cross polarisation and wide range of scan angle are required. View full abstract»

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    A multiport approach to modelling of phased antenna array for radio astronomy

    Tokarsky, P.L. ; Yerin, S.N.
    Microwave Conference (EuMC), 2013 European

    Publication Year: 2013 , Page(s): 1651 - 1654

    IEEE Conference Publications

    A two-stage approach for solving a large-scale electromagnetic problem which occurs in performing multivariate analysis of phased antenna arrays of low-frequency radio telescopes is proposed. At the first stage, the antenna array is presented as an equivalent multi-port network whose parameters are obtained through solving series of electromagnetic problems of antenna array excitation. At the second stage, the multiport network parameters are used for multivariate analysis of the antenna array performance for different amplitude-phase current distributions at its inputs. A possibility of applying the NEC2 software for estimating the multiport network parameters is shown. The results of numerical calculations of the gain, directivity and efficiency of the antenna array for a low frequency radio telescope are given. View full abstract»

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    Digitally controlled solar radio observations

    Oncica, A.
    Semiconductor Conference, 1998. CAS '98 Proceedings. 1998 International

    Volume: 2
    DOI: 10.1109/SMICND.1998.733827
    Publication Year: 1998 , Page(s): 623 - 626 vol.2

    IEEE Conference Publications

    Digitally controlled acquisition systems for solar radio telescopes are discussed from the point of view of astronomical requirements pointing out some technical specifications and experimental achievements View full abstract»

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    Calculation of the phase center of an ultra-wideband feed for reflector antennas

    Jian Yang
    Antennas & Propagation (ISAP), 2013 Proceedings of the International Symposium on

    Volume: 01
    Publication Year: 2013 , Page(s): 30 - 32

    IEEE Conference Publications

    Next generation ultra-wideband (UWB) radio telescopes require UWB feeds for reflector antennas. Different from narrow band feeds, how to determine the optimal phase center location for a UWB feed over a wide operating frequency band has not been investigated much and therefore analysis and discussions on this issue are needed. In this paper, a method for calculating the optimal phase center of a UWB feed is presented. Examples of the Eleven feeds, a decade bandwidth feed, are used to demonstrate the applications of the new method. View full abstract»

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    Valmar: High-bandwidth real-time streaming data management

    Bigelow, D. ; Brandt, S. ; Bent, J. ; Chen, H.B.
    Mass Storage Systems and Technologies (MSST), 2012 IEEE 28th Symposium on

    DOI: 10.1109/MSST.2012.6232387
    Publication Year: 2012 , Page(s): 1 - 6

    IEEE Conference Publications

    In applications ranging from radio telescopes to Internet traffic monitoring, our ability to generate data has outpaced our ability to effectively capture, mine, and manage it. These ultra-high-bandwidth data streams typically contain little useful information and most of the data can be safely discarded. Periodically, however, an event of interest is observed and a large segment of the data must be preserved, including data preceding detection of the event. Doing so requires guaranteed data capture at source rates, line speed filtering to detect events and data points of interest, and TiVo-like ability to save past data once an event has been detected. We present Valmar, a system for guaranteed capture, indexing, and storage of ultra-high-bandwidth data streams. Our results show that Valmar performs at nearly full disk bandwidth, up to several orders of magnitude faster than flat file and database systems, works well with both small and large data elements, and allows concurrent read and search access without compromising data capture guarantees. View full abstract»

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    A 5GS/s 4-bit time-based single-channel CMOS ADC for radio astronomy

    Macpherson, A.R. ; Haslett, J.W. ; Belostotski, L.
    Custom Integrated Circuits Conference (CICC), 2013 IEEE

    DOI: 10.1109/CICC.2013.6658551
    Publication Year: 2013 , Page(s): 1 - 4
    Cited by:  Papers (1)

    IEEE Conference Publications

    A 4-bit 65nm time-based analog-to-digital converter (ADC) targeting the next-generation Square Kilometre Array (SKA) is presented. This ADC is composed of an analog voltage-to-time converter (VTC) front end and a digital time-to-digital converter (TDC) back end. The two components can be physically separated to minimize the impact of digital noise from the ADC on high-gain, high-sensitivity receiver chains common in radio telescopes. At a sampling rate of 5 GS/s the ADC consumes 35 mW from a 1 V supply. After calibration, the ADC achieves a peak SNDR of 22.9 dB, SFDR of 34.0 dB and ENOB of 3.5. At the ERBW of 2100 MHz, SNDR is 18.4 dB, SFDR is 22.3 dB and ENOB is 2.8. The resulting worst-case figure of merit is 1.0 pJ/conversion. This is the highest reported sampling rate for a time-based ADC to date. View full abstract»

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    Statistical Characteristics of atmospheric phase fluctuations observed by a VLBI system using a beacon wave from a geostationary Satellite

    Qinghui Liu ; Nishio, M. ; Yamamura, K. ; Miyazaki, T. ; Hirata, M. ; Suzuyama, T. ; Kuji, S. ; Iwadate, K. ; Kameya, O. ; Kawano, N.
    Antennas and Propagation, IEEE Transactions on

    Volume: 53 , Issue: 4
    DOI: 10.1109/TAP.2005.844412
    Publication Year: 2005 , Page(s): 1519 - 1527
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    This paper reports the statistical characteristics of phase fluctuations obtained by a very long baseline interferometry, which received beacon waves from a geostationary satellite. Observations were made in different weather conditions by the 6-m Kagoshima and the 10-m Mizusawa radio telescopes, which were 1284 km apart from one another. Atmospheric phase fluctuations ranging from 0.2 to about 1000 s were detected. To study a variety of statistical characteristics of these phase fluctuations, the Allan standard deviation, σy(τ), the temporal structure function, Dφ(τ), and the square root of power spectrum, Gφ(f), were calculated from the observation results. These qualities were found to depend on the time interval τ or the frequency f (f=1/2τ) as follows: σy(τ)∝τ-0.6, τ-0.3, Dφ(τ)∝τ0.9, τ1.3 for 0.2 s<τ<1.5 s and 1.5 s<τ<400 s. Gφ(f)∝f-0.8 for 2.5 Hz>f>0.33 Hz and Gφ(f)∝f-1.3 for 0.33 Hz>f>0.00125 Hz. The curves of σy(τ) and Dφ(τ) exhibited shifts whose magnitudes followed the weather order clear, cloudy, and rainy. For τ>1.5 s (or f<0.33 Hz), the experimental results were consistent with the theoretical values predicted by Kolmogorov's turbulence theory and a frozen-screen model, but for τ<1.5 s (or f>0.33 Hz), the model has to be modified to explain the experimental results. View full abstract»

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    A wideband dipole feed for big reflector antenna

    Yu Jinglong ; Jin Chengjin
    Antennas & Propagation (ISAP), 2013 Proceedings of the International Symposium on

    Volume: 02
    Publication Year: 2013 , Page(s): 650 - 652

    IEEE Conference Publications

    A wideband dipole feed with symmetrical E&H plane patterns is presented for use in reflector antennas. In this paper we describe the design, construction and characterization of a wideband dipole feed for FAST antennas covering the frequency range 70 to 140 MHz. Main goals of our design are, 1) covering octave bandwidth, 2) the feed has symmetrical E & H plane patterns, and 3) the physical dimension is suitable for mounting it in the reserved position of the FAST feed cabin . We hope that four frequency range of FAST antennas will be equipped with this wideband dipole feeds. Preliminary simulation results indicate that we have met most of our design goals. View full abstract»

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    A Conceptual Framework for Pre Deployment Network Analysis of specification driven systems

    Varshney, G. ; Joshi, R.C. ; Sardana, A. ; Natarajan, S.N. ; Chaudhuri, S.R.
    Computer & Information Science (ICCIS), 2012 International Conference on

    Volume: 2
    DOI: 10.1109/ICCISci.2012.6297148
    Publication Year: 2012 , Page(s): 868 - 873

    IEEE Conference Publications

    Model driven development is at peak now days, where an application/system executes on a model with its predefined specifications. The specifications are a collection of data acquisition, validation checks, state machine descriptions and auxiliary information that describe the behavioral aspects of the application/system under consideration. In such type of specification driven machine control systems there is a great opportunity for high level pre-deployment analysis based on the information about the characteristics of the system that inherently exist in the specification files that drive them, with extra specifications, based on the kind and domain of analysis one is interested in. This provides a great opportunity for analysis of system specifications before deployment, that can help to figure out whether they are correct or not. One such application that we found in this context is of analyzing the networking behavior of an application based on its specification. In this paper we present a Conceptual Framework for Pre Deployment Network Analysis of Specification driven Monitoring and Control system and prototype implementation of a tool that does a high level network analysis of a hypothetical specification based system based on GMRT system. The paper also describes the specification files which contain network and expert (usage context) specifications that are necessary for such an analysis. View full abstract»

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    Detection and blanking of GSM interference in radio-astronomical observations

    Leshem, A. ; van der Veen, A.-J. ; Deprettere, E.
    Signal Processing Advances in Wireless Communications, 1999. SPAWC '99. 1999 2nd IEEE Workshop on

    DOI: 10.1109/SPAWC.1999.783096
    Publication Year: 1999 , Page(s): 374 - 377
    Cited by:  Papers (4)

    IEEE Conference Publications

    Radio-astronomical observations are increasingly disturbed by man-made communication signals, satellite and broadcast services. In particular, the GSM band is a highly saturated domain, full with interferers which are much stronger than radio astronomical signals. We propose a strategy to reduce this interference using its non-stationary nature. We describe a multichannel interference detector which enables us to reduce the interference by rejecting corrupted time-frequency slots. The use of multichannel detection greatly improves performance over previously suggested single channel detectors. This paper is the first to propose the implementation of advanced array signal processing methods for interference detection in radio astronomical observations View full abstract»

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    Experiment study on the motion planning and control of focus cabin of FAST

    Hao Jianlin ; Jing Fengshui ; Yang Guodong ; Liang Zize ; Zhu Lichun
    Control Conference (CCC), 2013 32nd Chinese

    Publication Year: 2013 , Page(s): 4265 - 4269
    Cited by:  Papers (2)

    IEEE Conference Publications

    The cable is easily aroused to vibrate in the process of Source Changing by the unsmooth cable velocity because the cable only can sustain tension but cannot bear thrust. What is worse, the position error of the end point of Source Changing was unacceptable. In this paper, different methods were used to find out the most suitable. The experiments on the scale model were conducted and the experiments data were analyzed. Eventually, the motion planning algorithm based on a continuous acceleration with attitude planning strategy was adopted because of the minor vibration of the cable and the higher accuracy of the end point of Source Changing. The effectiveness of the algorithm in this paper was verified. View full abstract»

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    Gaussian-beam analysis of a large adaptive reflector antenna (LAR) using a feed-reflector

    Mousavi, P. ; Shafai, L. ; Veidt, B. ; Daneshmand, M.
    Microwaves, Antennas and Propagation, IEE Proceedings

    Volume: 150 , Issue: 1
    DOI: 10.1049/ip-map:20030440
    Publication Year: 2003 , Page(s): 43 - 48

    IET Journals & Magazines

    A novel approach for analysing the quasi-optical large adaptive reflector Cassegrain system is described. In this system a feed-reflector is used to illuminate a hyperboloid sub-reflector with 5-10 m diameter, located 500 m above the ground. In the proposed method of analysis the feed-reflector aperture field distribution is expanded into a set of Gaussian-Laguerre modes. These modes propagate from the feed-reflector aperture in a simple and well defined way. The feed-reflector near-field radiation pattern is calculated at the subreflector location. The subreflector parameters in this system are found by maximising the LAR aperture efficiency, which includes phase and taper efficiencies, and minimising the LAR spillover loss. This process is computationally more efficient than the physical-optics current-distribution method and more accurate than the ray-tracing approach. It also provides a new insight into the operation of the feed-reflector system. View full abstract»

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    Characterisation of near-field focusing with application to low altitude beam focusing of the Arecibo tri-reflector system

    Kildal, P-.S ; Davis, M.M.
    Microwaves, Antennas and Propagation, IEE Proceedings

    Volume: 143 , Issue: 4
    DOI: 10.1049/ip-map:19960388
    Publication Year: 1996 , Page(s): 284 - 292
    Cited by:  Papers (1)

    IET Journals & Magazines

    Antennas are normally characterised in terms of their far field radiation patterns, directive gain and aperture efficiency. The paper describes how to characterise antennas that are focused in the near field, in terms of a focusing gain and a focusing efficiency. The paper also presents an algorithm from which the location of the near-field focus can be calculated directly from the aperture field of the antenna. The definitions and the algorithm are applied to an extensive numerical study of focusing of the beam of the Arecibo tri-reflector system at low altitudes. The focusing is obtained by displacing the feed, or the tertiary reflector, or both at the same time. Finally, an approximate formula is presented, from which results can be calculated easily at other frequencies and altitudes than those being computed View full abstract»

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    Mobility analysis of the large adaptive reflector antenna reflector

    Wang, D. ; Meng, M.
    Electrical and Computer Engineering, 2000 Canadian Conference on

    Volume: 2
    DOI: 10.1109/CCECE.2000.849589
    Publication Year: 2000 , Page(s): 865 - 869 vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    The motion of the three-tethered balloon system in the large adaptive reflector antenna is analyzed. First, the motion scale of the balloon in the sky is investigated, which is composed by three different spherical surfaces. Second, different materials always cause different static and dynamic deformation of the tether, so the affect of the material to the stability of the motion of balloon is discussed by using the scaled-down model for laboratory use. Third, the influence of the motion pattern of each tether to the motion stability of the balloon is given View full abstract»

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    A high precision square law detector in digital microwave radiometer

    Xin Pei ; Maozheng Chen ; Hao Yan ; Jian Li ; Xiaohong Liu
    Communication Software and Networks (ICCSN), 2011 IEEE 3rd International Conference on

    DOI: 10.1109/ICCSN.2011.6014425
    Publication Year: 2011 , Page(s): 211 - 214

    IEEE Conference Publications

    A new square law detector has been developed for digital microwave radiometer. It has a wider dynamic range and a more accurate square law response than has been available in the past. Experimental results show that the voltage sensitivity is higher than 0.9mV/uW and the linearity error is less than 0.3% in the frequency range from 100MHz to 2GHz and power range from -50dBm to -20dBm. Another advantage of the detector is its flatness, by selected a best type of diodes. Detailed detection circuit and measurement system have been given in this paper. View full abstract»

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    Arecibo Observatory 40th anniversary celebration

    Love, A.W.
    Antennas and Propagation Magazine, IEEE

    Volume: 46 , Issue: 1
    DOI: 10.1109/MAP.2004.1296152
    Publication Year: 2004 , Page(s): 94 - 97
    Cited by:  Papers (1)

    IEEE Journals & Magazines

    The National Astronomy and Ionosphere Center (NAIC), operated by Cornell University for the National Science Foundation, has its laboratory at Arecibo in Puerto Rico. The observatory's main instrument is a radio/radar telescope that utilizes a giant reflector antenna 1,000 feet in diameter, the largest in the world by considerable margin. A 40th anniversary celebration of the 1963 inauguration of this observatory was held at the site in Puerto Rico on November 1, 2003. This paper discusses the development of the said antenna, its characteristics and the upgrading of the system. The paper includes a discussion of what transpired during the said anniversary celebration. View full abstract»

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    Deep large area sky surveys at metre wavelengths using GMRT — Some challenges

    Sirothia, S.K.
    General Assembly and Scientific Symposium, 2011 XXXth URSI

    DOI: 10.1109/URSIGASS.2011.6051198
    Publication Year: 2011 , Page(s): 1

    IEEE Conference Publications

    We have been studying several fields (like ELAIS-N1, GOODS-N/S, AKARI deep field) and making their deep images at metre wavelengths using the GMRT. We are also carrying out, TIFR GMRT Sky Survey (TGSS). TGSS is radio continuum survey at 150 MHz, covering about 32000 sq. deg of the sky north of declination of -30 degrees and with typical rms noise of 7 mJy/beam at an angular resolution of about 20 arcsec. We describe some challenges and ways we tackle them for making these deep large area sky surveys at metre wavelengths using GMRT. View full abstract»

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    A quad-mode antenna for accurate polarimetric measurements over an ultra-wide field-of-view

    Prinsloo, D.S. ; Meyer, P. ; Ivashina, M.V. ; Maaskant, R.
    Antennas and Propagation (EuCAP), 2014 8th European Conference on

    DOI: 10.1109/EuCAP.2014.6902524
    Publication Year: 2014 , Page(s): 3260 - 3263
    Cited by:  Papers (1)

    IEEE Conference Publications

    The polarimetric performance of a quad-mode antenna element, consisting of a pair of crossed dipoles and an integrated monopole fed by a quadraxial transmission line, is analysed. Results are compared to a conventional dual-polarised antenna consisting of two orthogonal dipoles. The presented study shows that the quad-mode antenna effectively doubles the polarimetric capabilities of a dual-polarised antenna over the hemispherical field of view. View full abstract»

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    Characteristics and design of the LAR offset system with feed-reflector

    Mousavi, P. ; Shafai, L. ; Veidt, B. ; Daneshmand, M. ; Dewdney, P.
    Antennas and Propagation, IEEE Transactions on

    Volume: 51 , Issue: 7
    DOI: 10.1109/TAP.2003.813634
    Publication Year: 2003 , Page(s): 1462 - 1475

    IEEE Journals & Magazines

    A novel approach for analyzing the quasi-optical offset large adaptive reflector (LAR) Cassegrain system is described. In this system, a feed-reflector is used to illuminate a reconformable hyperboloid subreflector with 5-10 m diameter, located 500 m above the ground. An exact equation for the offset LAR surface is given. To scan the beam up to 60° which is one of the LAR requirements, the concept of the dual offset LAR with feed-reflector is introduced. In this design, the cross polarization is eliminated by a proper orientation of the subreflector. The parameters of the configuration are obtained by utilizing generalized Gauss-Laguerre beam modes and matrix representation of the beam mode transformation factor. The blockage effect due to the feed-reflector is totally removed. View full abstract»

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    An overview of electromagnetics, signal processing, imaging and calibration for MeerKAT

    Davidson, D.B. ; Jonas, J.
    Electromagnetics in Advanced Applications (ICEAA), 2012 International Conference on

    DOI: 10.1109/ICEAA.2012.6328640
    Publication Year: 2012 , Page(s): 308 - 311
    Cited by:  Papers (1)

    IEEE Conference Publications

    This paper provides an overview of the electromagnetics, signal processing, imaging and calibration for MeerKAT, the South African SKA precusor array currently under construction in the central Karoo, in the Northern Cape province of South Africa. The role of MeerKAT in SKA Phase 1 is addressed. View full abstract»

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    Millimetre wave generation using an optical comb generator with optical phase-locked loops

    Pengbo Shen ; Davies, P.A. ; Shillue, W.P. ; D'Addario, L.R. ; Payne, John M.
    Microwave Photonics, 2002. International Topical Meeting on

    DOI: 10.1109/MWP.2002.1158870
    Publication Year: 2002 , Page(s): 101 - 104
    Cited by:  Papers (5)

    IEEE Conference Publications

    We report the generation of millimetre wave signals to 158 GHz with phase noise better than 75 dBC/Hz at 100 kHz offset, by heterodyning of two lasers which are optically phase locked through an optical comb generator. View full abstract»

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    Improvement of the IRAM 30-m telescope from temperature measurements and finite-element calculations

    Greve, A. ; Bremer, M. ; Penalver, J. ; Raffin, P. ; Morris, D.
    Antennas and Propagation, IEEE Transactions on

    Volume: 53 , Issue: 2
    DOI: 10.1109/TAP.2004.838785
    Publication Year: 2005 , Page(s): 851 - 860
    Cited by:  Papers (7)

    IEEE Journals & Magazines

    Millimeter wavelength radio telescopes built in a conventional way from steel and aluminum require elaborate thermal control to guarantee small structural deformations and good observational performance. We describe the temperature monitoring system of the Institut de Radioastronomie Millime´trique 30-m telescope and the use of temperature measurements in finite-element calculations of structural deformations. These calculations reproduce with good precision the measured thermal deformations of the telescope and allow the investigation and localization of thermally important elements in the telescope structure. The data are used for calculation of temperature induced main reflector surface deformations and of the associated actual beam pattern, and for prediction and real-time correction of the focus. The pointing cannot be fully predicted since the available finite-element model does not include the Nasmyth focus cabin (and the concrete pedestal). The long-term investigation of the telescope's thermal behavior led to an improvement of the thermal control system and to a better performance of the telescope. View full abstract»

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    Wideband CMOS Amplification Stage for a Direct-Sampling Square Kilometre Array Receiver

    Navaratne, D. ; Belostotski, L.
    Microwave Theory and Techniques, IEEE Transactions on

    Volume: 60 , Issue: 10
    DOI: 10.1109/TMTT.2012.2210730
    Publication Year: 2012 , Page(s): 3179 - 3188
    Cited by:  Papers (2)

    IEEE Journals & Magazines

    The design of a second amplification stage (SAS) for a highly sensitive direct-sampling receiver for the Square Kilometre Array (SKA) radio synthesis telescope is discussed. The SAS is intended to follow a Square Kilometre Array low-noise amplifier (SKA-LNA), which is being designed by others and is not a subject of this study, to obtain the high gain required from the SKA receiver. Due to the SKA ultra-low noise-temperature requirements, the SAS noise must be minimized, even though it is preceded by an SKA-LNA. The first two stages of the SAS consist of an inductorless partially noise-canceling resistive-feedback amplifier and a differential gain stage that achieve both low noise figures (NFs) and convert the single-ended input signal to a differential output. Following this, an additional gain stage is cascaded to increase the SAS gain. Over the midband SKA frequency range of 0.7-1.4 GHz, a 65-nm CMOS SAS achieves an S21 >; 34 dB, voltage gain >;36 dB, and sub-1-dB NFs (~75-K noise temperature), P1dB of >; -52 dBm, input third-order intercept point (IP3) of >;-43 dBm and input second-order intercept point (IP2) of >;-34 dBm, while consuming 96.8 mW of dc power. While the proposed SAS is not required to be input power matched, a method for matching with minimum effect on NF and gain is also presented and experimentally verified. The power match SAS achieves an S21>;26dB, voltage gain >;35 dB, and sub-1.6-dB NFs (~130-K noise temperature), input P1dB of >;-52 dBm, input IP3 of >;-44 dBm, and input IP2 of >;-34 dBm, while consuming 58.9 mW of dc power. View full abstract»

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    Future challenges for radio astronomy

    O'Neil, K. ; Ford, J. ; McCarty, M. ; Minter, T. ; Prestage, R.
    Radio Science Meeting (USNC-URSI NRSM), 2013 US National Committee of URSI National

    DOI: 10.1109/USNC-URSI-NRSM.2013.6524991
    Publication Year: 2013 , Page(s): 1

    IEEE Conference Publications

    The challenge of maintaining quiet skies for radio astronomy continues to evolve rapidly, as it has done for the past 50 or more years. Increased emissions from electronics devices, increased power, ready embedding of digital and wireless electronics, and the increased power and frequency agility of many transmitters combine to make the successful scientific operation of any radio astronomy telescope challenging. This is compounded by the increasing desire to observe outside of the radio astronomy protected bands, e.g. to perform broadband pulsar observations, or to observe redshifted HI. View full abstract»

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    A renaissance in low-frequency radio pulsar and fast transient science

    Hessels, J.W.T.
    General Assembly and Scientific Symposium (URSI GASS), 2014 XXXIth URSI

    DOI: 10.1109/URSIGASS.2014.6930048
    Publication Year: 2014 , Page(s): 1 - 4

    IEEE Conference Publications

    Low-frequency, high-time-resolution radio studies have seen a renaissance in the last years not only because of the new generation of large radio telescopes but perhaps even more importantly because modern computing technology is facilitating high-resolution, wide-field observations. I will present ongoing pulsar and fast transient studies with LOFAR and the GBT at frequencies from 10-400 MHz. I will highlight the scientific successes of these studies, including the discovery of the first pulsar in a stellar triple system, as well as new insights into the magnetospheres of radio pulsars. These projects are pushing the envelope of big data in radio astronomy. For example, our LOFAR survey produces 40Gb/s of data, and the > 1Petabyte of data we have already acquired will take many millions of CPU core hours to reduce. These challenges are being successfully tackled, and are setting us on the path to make another big scientific leap with the Square Kilometer Array (SKA), where virtually all such data will have to be processed in real-time. View full abstract»

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    Deconvolution of VLBI images based on compressive sensing

    Suksmono, A.B.
    Electrical Engineering and Informatics, 2009. ICEEI '09. International Conference on

    Volume: 01
    DOI: 10.1109/ICEEI.2009.5254805
    Publication Year: 2009 , Page(s): 110 - 116
    Cited by:  Papers (2)

    IEEE Conference Publications

    Direct inversion of incomplete visibility samples in VLBI (very large baseline interferometry) radio telescopes produces images with convolutive artifacts. Since proper analysis and interpretations of astronomical radio sources require a non-distorted image, and because filling all of sampling points in the UV-plane is an impossible task, image deconvolution has been one of central issues in the VLBI imaging. Up to now, the most widely used deconvolution algorithms are based on least-squares-optimization and maximum entropy method. In this paper, we propose a new algorithm that is based on an emerging paradigm called compressive sensing (CS). Under the sparsity condition, CS capable to exactly reconstructs a signal or an image, using only a few number of random samples. We show that CS is well-suited with the VLBI imaging problem and demonstrate that the proposed method is capable to reconstruct a simulated image of radio galaxy from its incomplete visibility samples taken from elliptical trajectories in the uv-plane. The effectiveness of the proposed method is also demonstrated with an actual VLBI measured data of 3C459 asymmetric radio-galaxy observed by the VLA (very large array). View full abstract»

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    Radio Quiet Zones and the Square Kilometre Array

    van Driel, W.
    General Assembly and Scientific Symposium, 2011 XXXth URSI

    DOI: 10.1109/URSIGASS.2011.6051250
    Publication Year: 2011 , Page(s): 1 - 2

    IEEE Conference Publications

    The goal of the Square Kilometre Array is to increase the sensitivity of radio telescopes a hundred-fold in the frequency range of ~70 MHz to 10 GHz. In order to exploit its tremendous scientific capabilities it should be made as robust as possible against unwanted man-made Radio Frequency Interference (RFI). An essential part in this RFI protection scheme is the establishment of Radio Quiet Zones around the instrument, in which regulatory and other legislative measures will ensure acceptable levels of unwanted emissions that could degrade the quality of the astronomical data. An overview will be given of the principles underlying the establishment of Radio Quiet Zones in general, and their application to the Square Kilometre Array case. View full abstract»

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    Observing the Sun with the Murchison Widefield Array

    Oberoi, D. ; Sharma, R. ; Bhatnagar, S. ; Lonsdale, C.J. ; Matthews, L.D. ; Cairns, I.H. ; Tingay, S.J. ; Benkevitch, L. ; Donea, A. ; White, S.M. ; Bernardi, G. ; Bowman, J.D. ; Briggs, F. ; Cappallo, R.J. ; Corey, B.E. ; Deshpande, A. ; Emrich, D. ; Gaensler, B.M. ; Goeke, R. ; Greenhill, L.J. ; Hazelton, B.J. ; Johnston-Hollitt, M. ; Kaplan, D.L. ; Kasper, J.C. ; Kratzenberg, E. ; Lynch, M.J. ; McWhirter, S.R. ; Mitchell, D.A. ; Morales, M.F. ; Morgan, E. ; Offringa, A.R. ; Ord, S.M. ; Prabu, T. ; Rogers, A.E.E. ; Roshi, A. ; Salah, J.E. ; Shankar, N.U. ; Srivani, K.S. ; Subrahmanyan, R. ; Waterson, M. ; Wayth, R.B. ; Webster, R.L. ; Whitney, A.R. ; William, A. ; Williams, C.L.
    General Assembly and Scientific Symposium (URSI GASS), 2014 XXXIth URSI

    DOI: 10.1109/URSIGASS.2014.6930045
    Publication Year: 2014 , Page(s): 1 - 4

    IEEE Conference Publications

    The Sun has remained a difficult source to image for radio telescopes, especially at the low radio frequencies. Its morphologically complex emission features span a large range of angular scales and the emission mechanisms involved, span a wide range in brightness temperatures. In addition, time and frequency synthesis, the key tool used by most radio interferometers to build up information about the source being imaged is not effective for solar imaging, because many of the features of interest are short lived and change dramatically over small fractional bandwidths. Building on the advances in radio frequency technology, digital signal processing and computing, the kind of instruments needed to simultaneously capture the evolution of solar emission in time, frequency, morphology and polarization over a large spectral span with the requisite imaging fidelity, and time and frequency resolution have only recently begun to appear. Of this class of instruments, the Murchison Widefield Array (MWA) is best suited for solar observations. The MWA has now entered a routine observing phase and here we present some early examples from MWA observations. View full abstract»

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    Improved efficiency with a mechanically deformable subreflector

    Von Hoerner, S. ; Woon-Yin Wong
    Antennas and Propagation, IEEE Transactions on

    Volume: 27 , Issue: 5
    DOI: 10.1109/TAP.1979.1142142
    Publication Year: 1979 , Page(s): 720 - 723
    Cited by:  Papers (5)

    IEEE Journals & Magazines

    Like most conventional radio telescopes, the 140-ft at the National Radio Observatory (NRAO), Green Bank, WV, is limited in its short-wave performance by gravitational deformations, whose main part is of an astigmatic shape with elevation-dependant amplitude. This surface degradation could be corrected if a subreflector were deformed in a similar shape by the same amount. For testing this possibility an experimental Cassegrain subreflector was built which can be deformed in an astigmatic mode by simple means: two stiff diagonals and four points in-between where a motor pushes or pulls normal to the surface, servo-controlled by the on-line computer. Although the amount of deformation is too limited in the present setup, good results have already been obtained. Seven unresolved radio sources were observed at the water vapor line (22.3 GHz,lambda = 1.345cm), at various telescope pointing, and with different amounts of subreflector deformation, scanning in both directions for complete beam maps. The astigmatic deformation of the subreflector gave considerable improvements, especially fat south and east: fairly strong secondary beams disappeared; the beamshape became more symmetrical, narrow, and round; and at20degelevation the aperture efficiency increased by factors between two and three. View full abstract»

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    Tutorial: New telescopes, techniques, and observations

    Bower, G.C.
    Radio Science Meeting (USNC-URSI NRSM), 2013 US National Committee of URSI National

    DOI: 10.1109/USNC-URSI-NRSM.2013.6525068
    Publication Year: 2013 , Page(s): 1

    IEEE Conference Publications

    The past decade has seen an explosion of creativity and progress in radio astronomy telescopes and techniques. In the coming decade, we will harvest the fruit of these innovations with a powerful new generation of radio telescopes that are coming on line. These will open avenues for new science, in areas such as the epoch of reionization, synoptic surveys for radio transients, and exquisitely sensitive observations of the most distant objects in the Universe. View full abstract»

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    Multidimensional (MD) Circuits and Systems for Emerging Applications Including Cognitive Radio, Radio Astronomy, Robot Vision and Imaging

    Madanayake, A. ; Wijenayake, C. ; Dansereau, D.G. ; Gunaratne, T.K. ; Bruton, L.T. ; Williams, S.B.
    Circuits and Systems Magazine, IEEE

    Volume: 13 , Issue: 1
    DOI: 10.1109/MCAS.2012.2237141
    Publication Year: 2013 , Page(s): 10 - 43
    Cited by:  Papers (1)

    IEEE Journals & Magazines

    Advances in the performance of VLsi circuits are leading to a number of emerging applications of multidimensional (md) filters. Early progress was focused on the numerical design of two dimensional (2-d) transfer functions and the challenging stability issues associated with low-complexity infinite impulse response (iir) implementations. However, over the last decade or so, important practical advances have occurred in the design of 3-d and 4-d iir filters, leading to some important emerging applications. in this tutorial article, some of these applications are described, with emphasis on 2-d spatio-temporal beamforming and 4-d light field processing. in particular, advances in spatio-temporal beamforming for cognitive radio systems and for synthetic aperture radio telescopes are considered. in the 4-d case, we describe a class of 4-d light field filters for image processing, 4-d hyper-fan filters for low-light imaging, depth filtering, denoising and the attenuation of distracting objects, with applications in computational photography and habitat monitoring. Both analog and digital systolic VLsi circuit implementations are described with emphasis on recent progress using field programmable gate array (fPgA)-based and digital VLsi circuits that can potentially operate at radio frequencies in the multi-gHz range. these new innovations open up exciting possibilities for real-time md filters having frames rates in the multi-gHz for emerging radio frequency (rf) antenna signal processing and imaging systems. View full abstract»

  • Freely Available from IEEE

    Searching for ET with FPGA’S

    Werthimer, D.
    Field Programmable Logic and Applications, 2008. FPL 2008. International Conference on

    DOI: 10.1109/FPL.2008.4629897
    Publication Year: 2008 , Page(s): 3

    IEEE Conference Publications

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    Observations of total solar eclipses at short millimeter waves

    Rozanov, B.A. ; Zharkova, N.A.
    Physics and Engineering of Millimeter and Submillimeter Waves, 1998. MSMW '98. Third International Kharkov Symposium

    Volume: 2
    DOI: 10.1109/MSMW.1998.755517
    Publication Year: 1998 , Page(s): 566 - 568 vol.2

    IEEE Conference Publications

    The solar chromosphere is the source of the main part of the solar millimeter wave radiation. Its observation is very interesting for investigations of this very dynamic inhomogeneous layer near the solar temperature minimum. The lunar edge section method during solar eclipses gives some possibilities for the analysis of solar compact objects (the limb, active regions, filaments and so on) with high angular resolution using relatively low angular resolution instruments. Thus small millimeter wave radio telescopes may be useful for solar eclipse expedition observations. Such an instrument with antenna dish diameter of 0.6 m (RT-0.6) was designed at Bauman MSTU, in 1987. The antenna is equatorial mounted and moved in right ascension by a short-stepping quartz-controlled motor. The telescope is equipped with 3.4 mm wavelength heterodyne radiometer. Its sensitivity is 0.1 K with a 0.5 GHz bandwidth and 1 s integration time. The total weight of the telescope is 20 kg. Therefore it is useful for aircraft trips View full abstract»

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    Phased array feeds for the Square Kilometre Array

    van Cappellen, W. ; de Vaate, J.G.B. ; Warnick, K. ; Veidt, B. ; Gough, R. ; Jackson, C. ; Roddis, N.
    General Assembly and Scientific Symposium, 2011 XXXth URSI

    DOI: 10.1109/URSIGASS.2011.6051207
    Publication Year: 2011 , Page(s): 1 - 4
    Cited by:  Papers (2)

    IEEE Conference Publications

    A novel method to form multiple instantaneous beams on the sky with a reflector antenna is to employ a dense Phased Array Feed (PAF). This technology is currently being developed to greatly increase the survey speed of existing and future radio telescopes. This paper reviews the current state of PAF development projects for radio astronomy, the particular challenges and the potential for incorporation of PAFs into the ultimate radio survey instrument - the Square Kilometre Array. View full abstract»

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    A streaming approach to radio astronomy imaging

    Biem, A. ; Elmegreen, Bruce ; Verscheure, O. ; Turaga, D. ; Andrade, H. ; Cornwell, T.
    Acoustics Speech and Signal Processing (ICASSP), 2010 IEEE International Conference on

    DOI: 10.1109/ICASSP.2010.5495521
    Publication Year: 2010 , Page(s): 1654 - 1657

    IEEE Conference Publications

    The emergence of large-field radio telescopes has generated the need to process huge amounts of data “on the fly” in order to avoid substantial costs in storage and signal processing. In this paper, we describe a streaming software approach to radio astronomy, and in particular, show how the IBM-developed stream computing architecture System S enables seamless “on the fly” radio astronomy imaging. This approach overcomes pertinent issues of memory limitation and latencies related to data processing, and it allows autonomous processor allocation to tasks as the need arises. View full abstract»

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    MITEoR: A prototype highly scalable interferometer for 21 cm cosmology

    Dillon, J.S. ; Haoxuan Zheng ; Tegmark, M.
    Radio Science Meeting (USNC-URSI NRSM), 2014 United States National Committee of URSI National

    DOI: 10.1109/USNC-URSI-NRSM.2014.6928124
    Publication Year: 2014 , Page(s): 1

    IEEE Conference Publications

    Studying astrophysics and cosmology with the 21 cm line of neutral hydrogen requires extreme sensitivity and, therefore, radio telescopes with enormous collecting areas. Achieving that size with an interferometer is limited by the computational cost of the correlator, which scales as N2, where N is the number of antennas in the array. However, a large class of highly redundant interferometers can cut that scaling down to N logN. Redundant configurations also enable new algorithms for precise and automated calibration. For this reason we designed MITEoR, a 64-element, dual-polarization prototype radio interferometer designed to demonstrate these scalable technologies, which we constructed at MIT and deployed this summer in The Forks, Maine. We report on the results of MITEoR and the lessons learned for next generation radio interferometers. View full abstract»

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    Site requirements and challenges for low frequency radio observations

    Millenaar, R.
    General Assembly and Scientific Symposium, 2011 XXXth URSI

    DOI: 10.1109/URSIGASS.2011.6051189
    Publication Year: 2011 , Page(s): 1

    IEEE Conference Publications

    Observing the early universe, in particular the detection of the signature of the EOR is an important science target for the SKA and other new radio telescopes. These high redshift observations require excellent performance at low frequencies, as low as 50 MHz. Observations will be carried out in a crowded part of the radio spectrum, even at the very radio-quiet sites that are considered. Propagation of RFI at these frequencies can be highly variable and the influence of the ionosphere on propagation is felt strongly in this frequency range. An overview of issues and challenges is presented. View full abstract»

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    Radio astronomy image enhancement in the presence of phase errors using genetic algorithms

    Fridman, P.
    Image Processing, 2001. Proceedings. 2001 International Conference on

    Volume: 3
    DOI: 10.1109/ICIP.2001.958193
    Publication Year: 2001 , Page(s): 612 - 615 vol.3

    IEEE Conference Publications

    Modern radio astronomy interferometric telescopes use Earth rotation aperture synthesis imaging techniques. New projects for radio telescopes include hundreds and thousands of elements and presume multibeam and snapshot imaging. Each element, or base station, in its turn is a phase-array antenna. Phase instabilities due to instrumentation and atmospheric phase variations can ruin the synthesized image. There is a need to calibrate both the base stations and the whole interferometric configuration. A method of image enhancement of a calibration radio source, in the presence of phase errors, using genetic algorithm optimization techniques is described. Image sharpness is chosen as a cost function in the process of optimization. Computer simulations show the considerable positive effects in both applications View full abstract»

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    ASTRO-G/VSOP-2 off-set cassegrain telescope

    Kimura, K. ; Ogawa, H. ; Ujihara, H. ; Kishimoto, N. ; Kawahara, K. ; Mizuno, T. ; Murata, Y. ; Natori, M.C. ; Hirabayashi, H. ; Tsuboi, M. ; Higuchi, K. ; Saito, H. ; Yoshihara, M. ; Iikura, S.
    Antennas and Propagation Society International Symposium, 2008. AP-S 2008. IEEE

    DOI: 10.1109/APS.2008.4619071
    Publication Year: 2008 , Page(s): 1 - 4
    Cited by:  Papers (1)

    IEEE Conference Publications

    Following the success of the first VLBI Space Observatory Programme (VSOP), a satellite of a next space VLBI project, ASTRO-G/VSOP-2, is being designed. Very long baseline interferometry (VLBI) is a technique to achieve very high angular resolution imaging of celestial radio sources by combining the signals from widely separated radio telescopes. Space VLBI extends the separation beyond the Earth by placing one telescope on a satellite. View full abstract»

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    Earth rotation parameters determined by VLBI within project IRIS

    Schuh, H.
    Instrumentation and Measurement, IEEE Transactions on

    Volume: 38 , Issue: 2
    DOI: 10.1109/19.192375
    Publication Year: 1989 , Page(s): 676 - 679

    IEEE Journals & Magazines

    The very long baseline interferometry (VLBI) project for international radio interferometric surveying (IRIS) is presented. It involves three stations in the United States (Westford, MA; Ft. Davis, TX; Richmond, FL) and two radio telescopes in Europe (Wettzell, West Germany, and Onsala, Sweden). The IRIS experiments provide all of the Earth orientation parameters (UT1, polar motion, and nutation), baseline components, extragalactic radio source positions, and parameters of geophysical and astronomical models. For the investigation of the short periods of polar motion, the pole path observed within project IRIS since January 1984 was analyzed in the along-track and cross-track components. Both components contain variations with periods of ≈13.7 days. A comparison of the phases shows that the fortnightly variation of the cross-track components can be related to the variation of the tidal potential (Earth tides and/or ocean tides with a period of 13.66 days) with a phase lag of about one day. The largest variations were found in the along-track pole components, with an average period of ≈10.8 days. This confirms the assumption recently made by several authors that the short-period variations in global atmospheric data-with periods of 10-12 days-influence the motion of the pole View full abstract»

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    Radio astronomical researches of the sun in CrAO (to the anniversary of SIMEIZ-100)

    Tsvetkov, L.I. ; Yurovsky, Y.F.
    Microwave & Telecommunication Technology, 2008. CriMiCo 2008. 2008 18th International Crimean Conference

    DOI: 10.1109/CRMICO.2008.4676281
    Publication Year: 2008 , Page(s): 37 - 40

    IEEE Conference Publications

    The radio telescopes of KRAO intended for the systematic monitoring of solar activity with the purpose of prognostication of the space weather in a neighborhood of Earth are listed. The equipment for research of sources of generation of sporadic solar radio emission is described. The stages of modernization by the antenna system of RT-22 and engineering solutions in the researches of polarization of solar radio emission are briefly described. View full abstract»

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    Large 22-MHz array for radio astronomy

    Costain, C.H. ; Lacey, J. ; Roger, R.S.
    Antennas and Propagation, IEEE Transactions on

    Volume: 17 , Issue: 2
    DOI: 10.1109/TAP.1969.1139409
    Publication Year: 1969 , Page(s): 162 - 169
    Cited by:  Papers (2)

    IEEE Journals & Magazines

    The relative merits of T- and cross-type radio telescopes are discussed. A large array used for radio astronomical studies at a frequency of 22.25 MHz (lambda = 13.5m) is described. It is built in the form of a T with dimensions96lambda times 2.5lambdaeast-west and32.5lambda times 4lambdanorth-south. The 624 full-wave dipoles are mountedlambda/8above a 65 000 m2reflecting screen. The instrument has a pencil-beam response of1.1 times 1.7degrees at the zenith. A timesharing technique is used to provide simultaneous observations of 5 adjacent declinations spaced at quarter-beamwidth intervals. Observations, commenced in 1965, should provide flux density measures for 400-500 radio sources down to a limiting flux density of about30 times 10^{-26}W .m-2Hz-1. A map of the galactic background radiation from declination +90 to -20 degrees is being prepared. View full abstract»

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    Telescopes for IPS observations

    Li-Jia Liu ; Lan-Chuan Zhou ; Bin Liu ; Cheng-Jin Jin ; Bo Peng
    Antennas & Propagation (ISAP), 2013 Proceedings of the International Symposium on

    Volume: 01
    Publication Year: 2013 , Page(s): 37 - 40

    IEEE Conference Publications

    The sun especially the solar wind have influenced our Earth in many ways, and observing the solar wind is an important method to study the solar-earth environment. Interplanetary Scintillation (IPS) observations are an effective method of monitoring solar wind, forecasting the solar-terrestrial space weather and studying the structures of the long distance compact radio sources. Since the discovery of Interplanetary Scintillation, many countries began to use this method to study the solar wind and the interplanetary plasma, so some appropriative radio telescopes were built to achieve these goals. In this paper, we will review some typical IPS radio telescopes and also the current status of IPS study in China. View full abstract»

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    A Waveform Receiver for Continuous Registration of Fast Processes in Pulsar Radio Emission

    Zakharenko, V.V. ; Nikolaenko, V.S. ; Ulyanov, O.M. ; Motiyenko, R.A.
    Physics and Engineering of Microwaves, Millimeter and Submillimeter Waves and Workshop on Terahertz Technologies, 2007. MSMW '07. The Sixth International Kharkov Symposium on

    Volume: 2
    DOI: 10.1109/MSMW.2007.4294800
    Publication Year: 2007 , Page(s): 745 - 747

    IEEE Conference Publications

    This paper presents the investigation of fast processes in radio emission of pulsars, magnetars, RRATs, etc. demands a long continuous recording with high time resolution. Now pulse radio emissions from magnetosphere of different kind of neutron stars are observed in the range from decameter wave length up to 40 GHz. In the lowest one - decameter wave range it's very difficult to achieve high time resolution due to effects of scattering and dispersive delay of the pulse propagation in the interstellar medium (ISM) which lead to the broadening of pulse signal in the receiving band. In spectral receivers, real time digital receivers with fast Fourier transform (FFT) or in the filter bank analyzers time resolution is determined by the pulse broadening in the frequency band of a single digital channel. The analogue part of the receiver - amplifiers and mixers for the work under high level of interference have been worked off long ago in the equipment developed in the RINAN of Ukraine for the radio telescopes UTR-2 and URAN. View full abstract»

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    An 800 GHz NbN phonon-cooled hot-electron bolometer mixer receiver

    Kawamura, J.H. ; Tong, C.-Y.E. ; Blundell, R. ; Cosmo Papa, D. ; Hunter, T.R. ; Gol'tsman, G. ; Cherednichenko, S. ; Voronov, B. ; Gershenzon, E.
    Applied Superconductivity, IEEE Transactions on

    Volume: 9 , Issue: 2 , Part: 3
    DOI: 10.1109/77.783844
    Publication Year: 1999 , Page(s): 3753 - 3756
    Cited by:  Papers (5)

    IEEE Journals & Magazines

    We describe a heterodyne receiver developed for astronomical applications to operate in the 350 /spl mu/m atmospheric window. The waveguide receiver employs a superconductive NbN phonon-cooled hot-electron bolometer mixer. The double sideband receiver noise temperature closely follows 1 kGHz/sup -1/ across 780-870 GHz, with the intermediate frequency centered at 1.4 GHz. The conversion loss is about 15 dB. The receiver was installed for operation at the University of Arizona/Max Planck Institute for Radio Astronomy Submillimeter Telescope facility. The instrument was successfully used to conduct test observations of a number of celestial sources in a number of astronomically important spectral lines. View full abstract»

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    Scaling and stationarity analysis of discrete time signal of Solar Radio flux

    Kumar, C. ; Prasad, A. ; Barui, R. ; Patra, S.N. ; Ghosh, K.
    Control, Instrumentation, Energy and Communication (CIEC), 2014 International Conference on

    DOI: 10.1109/CIEC.2014.6959161
    Publication Year: 2014 , Page(s): 608 - 611

    IEEE Conference Publications

    In the present work, we have considered the daily signal of Solar Radio flux of 2800 Hz recorded daily by radio telescopes near Ottawa (operated during 14th February, 1947-31st May, 1991) and Penticton, British Columbia, Dominion Radio Astrophysical Observatory (operating since 1st June, 1991) during the period from 29th October, 1972 to 28th February, 2013. We have applied FIR nonlinear phase filter on the present discrete signal to denoise it. The memory of this denoising signal has been analyzed and it indicates short memory trend (anti-persistent) hidden in this spectrum. Then we have examined whether the signal possesses stationary properties. On the basis of autocorrelation analysis, quasi or partly stationary nature of the spectrum has been revealed. View full abstract»

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    A Wideband Superconducting Filter Using Strong Coupling Resonators for Radio Astronomy Observatory

    Tao Yu ; Chunguang Li ; Fei Li ; Qiang Zhang ; Liang Sun ; Lu Gao ; Yuehui Wang ; Xueqiang Zhang ; Hong Li ; Chengjin Jin ; Jianbin Li ; Hongfei Liu ; Changzheng Gao ; Jibao Meng ; Yusheng He
    Microwave Theory and Techniques, IEEE Transactions on

    Volume: 57 , Issue: 7
    DOI: 10.1109/TMTT.2009.2022812
    Publication Year: 2009 , Page(s): 1783 - 1789
    Cited by:  Papers (8)

    IEEE Journals & Magazines

    A 12-pole wideband superconducting microstrip bandpass filter, which has a fractional bandwidth of 38% and a center frequency of 1455 MHz, is presented for the Miyun 50-m radio astronomy telescope, Beijing, China. A novel resonator, which can not only generate very large coupling, but also push its first spurious resonant peak away from the passband, is introduced. A new style interleaved coupling structure is proposed and successfully used in this study to realize the remarkably required strong coupling. To achieve high edge slope on the high side of the passband, as required, a single transmission zero was introduced. The filter was fabricated on a 36 mm times 30 mm times 0.5 mm double-sided YBa2Cu3O7 film deposited on an MgO substrate. The measured results showed that the filter had 0.05-dB minimum insertion loss, 0.08-dB passband ripple, and 23-dB return loss at a temperature of 40 K. The first spurious peak did not appear until 2632 MHz. The overall measured performance showed good agreement with the simulation. View full abstract»

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    Telescope surface measurement with two feeds

    Von Hoerner, S.
    Antennas and Propagation, IEEE Transactions on

    Volume: 26 , Issue: 6
    DOI: 10.1109/TAP.1978.1141948
    Publication Year: 1978 , Page(s): 857 - 860
    Cited by:  Papers (1)

    IEEE Journals & Magazines

    A method is suggested where a reference feed is fixed at the telescope focus, and a second feed has a lateral offset and scans the focal plane. The telescope tracks a celestial radio source, and the receiver measures the phase difference at the two feeds and their (voltage) amplitude ratio. A set of coordinate transformations is applied, after which the surface deviationssigmafrom a paraboloid can be obtained by a Fourier transform. The measuring error is discussed, and the best wavelength is found to be between 14 and 21 rmssigma. View full abstract»

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    Time-frequency analysis of electromagnetic pollution in radio astronomy receivers

    Friedman, P.A.
    Time-Frequency and Time-Scale Analysis, 1996., Proceedings of the IEEE-SP International Symposium on

    DOI: 10.1109/TFSA.1996.550068
    Publication Year: 1996 , Page(s): 365 - 367

    IEEE Conference Publications

    The problem of radio frequency interference (RFI) in radio astronomy has become very critical during the last several years. The real sensitivity of radio telescopes is degraded by industrial noise. A method of combating RFI is proposed using time-frequency analysis and its implementation via digital signal processing in real time is discussed View full abstract»

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    Three-way Doppler observation of Mars Express

    Kun Shang ; Nianchuan Jian ; Jinsong Ping ; Xian Shi ; Sujun Zhang ; Jianguo Yan ; Mingyuan Wang
    Communications, 2009. APCC 2009. 15th Asia-Pacific Conference on

    DOI: 10.1109/APCC.2009.5375629
    Publication Year: 2009 , Page(s): 314 - 317

    IEEE Conference Publications

    Using the radio telescopes in Chinese VLBI Net (CVN) and the sampling board, we have developed algorithms that extract three-way Doppler information from the radio tracking data of Mars Express (MEX) - a Martian probe that belongs to European Space Agency (ESA). Our latest results indicate the accuracy of three-way Doppler is about 1 mm/s in 1 second integration time, relative to an 8.4 GHz carrier. The three-way Doppler data have been used in orbit determination of Mars Express. View full abstract»

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    The Noncoplanar Baselines Effect in Radio Interferometry: The W-Projection Algorithm

    Cornwell, T.J. ; Golap, K. ; Bhatnagar, S.
    Selected Topics in Signal Processing, IEEE Journal of

    Volume: 2 , Issue: 5
    DOI: 10.1109/JSTSP.2008.2005290
    Publication Year: 2008 , Page(s): 647 - 657
    Cited by:  Papers (7)

    IEEE Journals & Magazines

    We consider a troublesome form of nonisoplanatism in synthesis radio telescopes: noncoplanar baselines. We present a novel interpretation of the noncoplanar baselines effect as being due to differential Fresnel diffraction in the neighborhood of the array antennas. We have developed a new algorithm to deal with this effect. Our new algorithm, which we call ldquoW-projectionrdquo, has markedly superior performance compared to existing algorithms. At roughly equivalent levels of accuracy, W-projection can be up to an order of magnitude faster than the corresponding facet-based algorithms. Furthermore, the precision of result is not tightly coupled to computing time. W-projection has important consequences for the design and operation of the new generation of radio telescopes operating at centimeter and longer wavelengths. View full abstract»

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    Experimental Results for the Sensitivity of a Low Noise Aperture Array Tile for the SKA

    Woestenburg, E.E.M. ; Bakker, L. ; Ivashina, M.V.
    Antennas and Propagation, IEEE Transactions on

    Volume: 60 , Issue: 2 , Part: 2
    DOI: 10.1109/TAP.2011.2173140
    Publication Year: 2012 , Page(s): 915 - 921
    Cited by:  Papers (5)

    IEEE Journals & Magazines

    Aperture arrays have been studied extensively for application in the next generation of large radio telescopes for astronomy, requiring extremely low noise performance. Prototype array systems need to demonstrate the low noise potential of aperture array technology. This paper presents noise measurements for an Aperture Array tile of 144 dual-polarized tapered slot antenna (TSA) elements, originally built and characterized for use as a Phased Array Feed for application in an L-band radio astronomical receiving system. The system noise budget is given and the dependency of the measured noise temperatures on the beam steering is discussed. A comparison is made of the measurement results with simulations of the noise behavior using a system noise model. This model includes the effect of receiver noise coupling, resulting from a changing active reflection coefficient and array noise contribution as a function of beam steering. Measurement results clearly demonstrate the validity of the model and thus the concept of active reflection coefficient for the calculation of effective system noise temperatures. The presented array noise temperatures, with a best measured value of 45 K, are state-of-the-art for room temperature aperture arrays in the 1 GHz range and illustrate their low noise potential. View full abstract»

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    A new millimeter VLBI network in Korea

    Lee, S.-S. ; Kim, J. ; Byun, D.-Y.
    General Assembly and Scientific Symposium (URSI GASS), 2014 XXXIth URSI

    DOI: 10.1109/URSIGASS.2014.6930021
    Publication Year: 2014 , Page(s): 1

    IEEE Conference Publications

    Summary form only given. We introduce a new millimeter very long baseline interferometry (VLBI) network in Korea, the Korean VLBI Network (KVN). The KVN is the first millimeter-dedicated VLBI network in East Asia. The KVN consists of three 21 m radio telescopes with baseline lengths in a range of 305-476 km. The quasi-optical system equipped on the antennas allows simultaneous observations at 22, 43, 86, and 129 GHz. The first fringes of the KVN were obtained at 22 GHz on 2010 June 8. Test observations at 22 and 43 GHz on 2010 September 30 and 2011 April 4 confirmed that the full cycle of VLBI observations works according to specification: scheduling, antenna control system, data recording, correlation, post-correlation data processing, astrometry, geodesy, and imaging analysis. The KVN is ready to image compact radio sources both in snapshot and full-track modes with residual noise in calibrated phases of less than 2 deg at 22 and 43 GHz and with dynamic ranges of 300 for snapshot mode and 1000 for full-track mode. The KVN will be open to the world, calling for proposals in 2014. We will introduce high-lights of science cases of KVN such as detection of 44 GHz methanol masers, observations of Zeeman splitting effect, VLBI fringe detection of 129GHz SiO masers from evolved stars. View full abstract»

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    Beamformer Design Methods for Radio Astronomical Phased Array Feeds

    Elmer, M. ; Jeffs, B.D. ; Warnick, Karl F. ; Fisher, J.R. ; Norrod, R.D.
    Antennas and Propagation, IEEE Transactions on

    Volume: 60 , Issue: 2 , Part: 2
    DOI: 10.1109/TAP.2011.2173143
    Publication Year: 2012 , Page(s): 903 - 914
    Cited by:  Papers (4)

    IEEE Journals & Magazines

    A major emphasis in current radio astronomy instrumentation research is the use of phased array feeds (PAF) to provide radio telescopes with larger fields of view. One of the challenges of PAF systems is the design of beamformers that provide sufficient sensitivity and known, stable beam pattern structure. High sensitivity has been achieved with the maximum sensitivity beamformer without regard to beam pattern shape. Deterministic beamformers provide the desired pattern shape control, but suffer from a significant reduction in sensitivity. We present a hybrid beamforming method, which balances the tradeoff between high sensitivity and precise beam pattern shape control. A comparison of each of these beamforming methods, using measured data, confirms the advantage of the hybrid approach. The pattern distortions introduced by modeled beamformers can be mitigated with a transformation step, but ultimately it is shown that PAF beamformer design is best done using measured calibrators. A PAF calibration vector quality metric based on minimum description length is also introduced. View full abstract»

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    VLBI-observation of ‘Huygens’ probe

    van 't Klooster, K.
    Antenna Theory and Techniques, 2007 6th International Conference on

    DOI: 10.1109/ICATT.2007.4425115
    Publication Year: 2007 , Page(s): 57 - 58

    IEEE Conference Publications

    JIVE -Joint Institute for Very Long Baseline Interferometry (VLBI) in Europe -has managed under ESA contract the VLBI data acquisition of a stabile carrier-signal from Huygens' probe during landing on Titan in January 2004, using ~17 radio telescopes. Evaluation and investigation of the data is included in the same ESA contract. The scenario was described in a previous ICATT Conference (van 't Klooster, 2005). This presentation provides some published information of Huygens descent-trajectory as derived by JIVE. VLBI can be used for special radio-physical investigations, accurate Doppler information is a by-product. VLBI is applied now and in space-missions to come: probes, landers or spacecrafts for navigational, scientific or even telemetry tasks. View full abstract»

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    Bandwidth limits of beamforming networks for focal-plane arrays

    Veidt, B. ; Dewdney, P.
    Antennas and Propagation Society International Symposium, 2003. IEEE

    Volume: 1
    DOI: 10.1109/APS.2003.1217418
    Publication Year: 2003 , Page(s): 132 - 135 vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    Current designs for radio telescopes have only one radio beam, or at most a few separated beams. To increase sensitivity, future telescopes will have both multiple overlapping beams and instantaneous bandwidths approaching an octave. This advancement may be enabled by wideband phased arrays with closely spaced elements, such as Vivaldi antennas. These arrays can be placed at the focal plane of reflector antennas and the outputs combined in a beamforming network (BFN) to synthesize simultaneously multiple beams on the sky. The spacing of beams is much closer than possible with arrays of conventional horn antennas and satisfies Nyquist sampling conditions. In a focal-plane array BFN, the weights for the individual elements are set to match the field distribution of the focal spot for a single beam at the design frequency. With a simple ideal BFN, these weights are frequency independent, making the beam pattern of the feed frequency dependent. As a consequence, at frequencies below the design frequency, the reflector is over-illuminated, increasing the spillover noise received, and conversely, at higher frequencies, the reflector is under-illuminated, resulting in a loss of efficiency. The paper examines how the sensitivity of a focal-plane array varies as a function of bandwidth and briefly outlines methods to mitigate this effect. View full abstract»

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    The application of compressed sensing techniques in radio astronomy

    Scaife, A.M.M. ; Wiaux, Y.
    General Assembly and Scientific Symposium, 2011 XXXth URSI

    DOI: 10.1109/URSIGASS.2011.6051225
    Publication Year: 2011 , Page(s): 1 - 4
    Cited by:  Papers (1)

    IEEE Conference Publications

    Radio interferometry probes astrophysical signals through incomplete and noisy Fourier measurements. The optimal reconstruction of these signals is an important topic not only for current astronomical imaging but also that of the next generation of radio telescopes, for many of which image dynamic range is a key driver. The theory of compressed sensing demonstrates that incompletely sampled signals, such as those from an interferometer, may be accurately reconstructed when they are sparse or compressible in some basis. The introduction of an explicit sparsity constraint makes the method extremely versatile as it allows prior information on the signal to be introduced. Compressed sensing has been demonstrated to offer significant improvement over standard algorithms, and the flexibility of the framework and its implications for wide-field imaging are compelling, as is its potential for influencing data acquisition methods and improving data storage and transport. View full abstract»

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    Demonstration of a Dual-Polarized Phased-Array Feed

    Veidt, B. ; Hovey, G.J. ; Burgess, T. ; Smegal, R.J. ; Messing, R. ; Willis, A.G. ; Gray, A.D. ; Dewdney, P.E.
    Antennas and Propagation, IEEE Transactions on

    Volume: 59 , Issue: 6 , Part: 1
    DOI: 10.1109/TAP.2011.2122231
    Publication Year: 2011 , Page(s): 2047 - 2057
    Cited by:  Papers (14)

    IEEE Journals & Magazines

    We describe the design and construction of a dual-polarized phased-array feed (PAF) with the purpose of demonstrating this technology as a means of expanding the instantaneous field-of-view of radio telescopes. The PAF beamformer is calibrated with observations of an unpolarized astronomical radio source, the covariance matrix of all receiver channels is calculated, and the two dominant eigenvectors are then used as beamformer weights. We show measurements demonstrating the capabilities of this instrument as a polarimeter, and confirm that the calibration method does produce orthogonally-polarized beams. These results are then analyzed to show the sensitivity to fluctuations in gain and phase in the multiple parallel receiver chains making up the phased-array feed. We also compare the performance of PAFs that beamform all array elements with PAFs that beamform only co-polarized elements. View full abstract»

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    Signal processing challenges for radio astronomical arrays

    Wijnholds, S.J. ; van der Veen, A.-J. ; De Stefani, F. ; La Rosa, E. ; Farina, A.
    Acoustics, Speech and Signal Processing (ICASSP), 2014 IEEE International Conference on

    DOI: 10.1109/ICASSP.2014.6854631
    Publication Year: 2014 , Page(s): 5382 - 5386

    IEEE Conference Publications

    Current and future radio telescopes, in particular the Square Kilometre Array (SKA), are envisaged to produce large images (> 108 pixels) with over 60 dB dynamic range. This poses a number of image reconstruction and technological challenges, which will require novel approaches to image reconstruction and design of data processing systems. In this paper, we sketch the limitations of current algorithms by extrapolating their computational requirements to future radio telescopes as well as by discussing their imaging limitations. We discuss a number of potential research directions to cope with these challenges. View full abstract»

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    The DRAO Phased Array Feed Demonstrator: Recent results

    Veidt, B. ; Burgess, T. ; Messing, R. ; Hovey, G. ; Smegal, R.
    Antenna Technology and Applied Electromagnetics and the Canadian Radio Science Meeting, 2009. ANTEM/URSI 2009. 13th International Symposium on

    DOI: 10.1109/ANTEMURSI.2009.4805124
    Publication Year: 2009 , Page(s): 1 - 4
    Cited by:  Papers (9)

    IEEE Conference Publications

    Future radio telescopes will be used by astronomers to make high-sensitivity wide-band and wide-field surveys of the radio sky. A candidate technology to provide these expanded capabilities is to place high-sensitivity phased-arrays at the focal plane of reflector antennas. Since this technology has not been proven yet, we have constructed the PHased-Array feed Demonstrator (PHAD) with the goal of exploring engineering aspects of this new technology. PHAD comprises 180 densely-packed Vivaldi elements operating from 1 to 2 GHz. Each element feeds a low-noise amplifier and a receiver (both commercial integrated circuits), with the outputs digitized and stored. Beamforming is performed off-line using a matrix language, providing great flexibility in diagnostics and algorithm development. PHAD testing began in a near-field range and has progressed to tests on a dedicated 10-m reflector antenna. Early results (with emphasis on calibration) are reported here. View full abstract»

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    Initial calibration and beamforming results from the thousand element phased-array

    Hampson, G.A. ; bij de Vaate, J.G.
    Antennas and Propagation Society International Symposium, 2001. IEEE

    Volume: 2
    DOI: 10.1109/APS.2001.959797
    Publication Year: 2001 , Page(s): 610 - 613 vol.2
    Cited by:  Papers (3)

    IEEE Conference Publications

    The next generation of radio telescopes for astronomy are planned to have a receiving area of a square kilometer, known as a Square Kilometer Array (SKA). The technology can be based on phased arrays. ASTRON is currently building a THousand Element Array (THEA) to develop this technology. THEA consists of sixteen one square meter tiles each consisting of an eight by eight half wavelength spaced regular grid of antenna elements. The beamforming for THEA is done at two levels; radio frequency (RF) beamforming on every tile (64 elements) and digital beamforming with the sixteen tiles. The two level beamforming hierarchy is a cost effective method of producing large antenna arrays. This paper presents some initial results from a single THEA tile. Calibration of the tile is broken into two separate parts; the individual phase shifters (vector modulators) and the gain and phase offsets introduced by each receiving antenna and circuitry. Calibration results are presented, as well as, the resulting beam patterns produced by the tile. View full abstract»

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    The Allen Telescope Array: splitting the aperture

    DeBoer, D.R. ; Bock, D.C.J.
    Microwave Magazine, IEEE

    Volume: 5 , Issue: 2
    DOI: 10.1109/MMW.2004.1306835
    Publication Year: 2004 , Page(s): 46 - 53
    Cited by:  Papers (4)

    IEEE Journals & Magazines

    Most science applications in radio astronomy require great sensitivity and, thus, large amounts of collecting area and a quality receiver. Decoupling of the resolution and sensitivity is done by splitting the aperture into many antennas, where one may choose the sensitivity (number of antennas) independently of the resolution (spacing of the antennas). The ATA will be nearly as sensitive as the most sensitive current radio telescopes because it will have a large collecting area, about 10,000 m2. However, the ATA will be unusual in several respects: it will have a wide field of view (about 5 deg2 at 1,420 MHz - for reference, the moon and Sun are each about 0.2 deg2), continuous frequency coverage from 0.5 to 11.2 GHz (with simultaneous observations possible throughout the band), and a very large number of antennas. The technologies primarily enabling the ATA are low-cost ultra-wide-bandwidth analogue electronics and high-speed digital electronics, as well as "mid-quantity" production techniques. View full abstract»

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    EMBRACE, a 10000 element next generation aperture array telescope

    Ruiter, M. ; van der Wal, E.
    Microwave Conference, 2009. EuMC 2009. European

    Publication Year: 2009 , Page(s): 326 - 329
    Cited by:  Papers (7)

    IEEE Conference Publications

    A fully operational demonstrator for the next generation of radio telescopes is presented. EMBRACE is a phased array telescope with enormous potential for the astronomical community. New and innovative science can be performed using these type of telescopes, ultimately for SKA. We will give an overview of EMBRACE, its system architecture and components with its advantages, necessary compromises between performance and cost when building this demonstrator. View full abstract»

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    Local radio sources near polar region of the Sun observed during the eclipse on August 1, 2008

    Tsvetkov, L.I. ; Yurovsky, Yu.F.
    Microwave & Telecommunication Technology, 2009. CriMiCo 2009. 19th International Crimean Conference

    Publication Year: 2009 , Page(s): 924 - 926

    IEEE Conference Publications

    During observation of solar eclipse on the August 1, 2003 on radio telescopes RT-22 and RT-3 of the CrAO at wavelengths of 2,0; 2,8; 3,5; 10,5 and 12,5 cm the compact radio sources in subauroral area of the Sun which were conterminous by a position with bright EUR-patterns 195 A on the data SOHO were detected. View full abstract»

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    Design of tape systems for 0.1 to 10 Gbit/s applications [VLBA]

    Rogers, A. ; Hinteregger, Hans F.
    Magnetics, IEEE Transactions on

    Volume: 27 , Issue: 6 , Part: 2
    DOI: 10.1109/20.278674
    Publication Year: 1991 , Page(s): 4522 - 4525
    Cited by:  Papers (2)

    IEEE Journals & Magazines

    In some recorder applications there is a demand for both high data rates and high capacity. Radio astronomy is an example of such an application, and the longitudinal recorder has been developed for an array of radio telescopes known as the Very Long Baseline Array. The advantages, limitations, and future potential of this system are discussed in the light of new technologies for large arrays of heads, and extremely thin magnetic tapes View full abstract»

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    Ultra-Wideband Aperture Array Element Design for Low Frequency Radio Astronomy

    de Lera Acedo, E. ; Razavi-Ghods, N. ; Garcia, L.E. ; Duffett-Smith, P. ; Alexander, P.
    Antennas and Propagation, IEEE Transactions on

    Volume: 59 , Issue: 6 , Part: 1
    DOI: 10.1109/TAP.2011.2122218
    Publication Year: 2011 , Page(s): 1808 - 1816
    Cited by:  Papers (13)

    IEEE Journals & Magazines

    21st century Radio Astronomy at frequencies below 1 GHz will be dominated by arrays of thousands or millions of elements in configurations which are dense or sparse, regular or random, delivering data to powerful digital back-ends. High performance, specified by parameters such as the effective aperture and system noise temperature, will be crucial to achieve the ambitious survey speeds and sensitivities demanded by astronomers. In this paper we analyze the different trade-offs and difficulties in the design of ultra-wideband array antenna elements for these radio telescopes at frequencies below 500 MHz. Bandwidths of 7:1 are desired while using low-profile elements to keep the overall cost within the budget. View full abstract»

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    Digitizing The Yuan Tseh Lee Array for Microwave Background Anisotropy by 5Gsps ADC boards

    Homin Jiang ; Liu, H. ; Guzzino, K. ; Kubo, D. ; Chao-Te Li ; Chang, R.
    Electronics, Circuits and Systems (ICECS), 2012 19th IEEE International Conference on

    DOI: 10.1109/ICECS.2012.6463741
    Publication Year: 2012 , Page(s): 304 - 307
    Cited by:  Papers (1)

    IEEE Conference Publications

    An 8 bits, 5 Giga samples per second Analog to Digital Printed Circuit Board has been designed by the authors for digitizing The Yuan Tseh Lee Array for Microwave Background Anisotropy(AMiBA) and other radio telescopes. Associated with the Field Programmable Gate Array platform developed by the Collaboration for Astronomy Signal Processing and Electronics Research community, AMiBA will have a digital correlator system in the future, that was fiscally difficult in 2001 when it was at design phase. The board can digitize input radio frequencies from DC up to 2.5GHz with a flatness of 5dB. The ENOB ranges from 6.1 to 6.5 bits across the 2.5GHz band, the SFDR from 41 dB to 48 dB, and the SINAD from 32 dB to 37.5 dB if the gain and offset tuning is applied. View full abstract»

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    Minimum-noise maximum-gain telescopes and relaxation method for shaped asymmetric surfaces

    Von Hoerner, S.
    Antennas and Propagation, IEEE Transactions on

    Volume: 26 , Issue: 3
    DOI: 10.1109/TAP.1978.1141866
    Publication Year: 1978 , Page(s): 464 - 471
    Cited by:  Papers (6)  |  Patents (3)

    IEEE Journals & Magazines

    For future low-noise receivers, future radio telescopes must avoid the pickup of ground radiation, and for obtaining the maximum gain with a given diameter, they should be shaped two-mirror systems. A configuration with a double asymmetry is suggested, which would improve the signal-to-noise ratio by a factor of two to three. The asymmetric shaping problem is solved by a method of iterative relaxation. Starting with an original paraboloid-hyperboioid system, the primary surface is changed in each iteration for a gradual approach to the illumination demand, including the boundary condition that the circular aperture rim is represented by an exact circle of the feed pattern, and an exactly focussing secondary mirror is calculated in each iteration. The well-documented Fortran program can be obtained from the National Radio Astronomy Observatory (NRAO). All calculated examples, for various strongly asymmetric configurations, converged after 6-10 iterations (within a few minutes of computer time) to an aperture efficiency ofeta geq 99.97percent (for geometrical optics). The maximum change of the primary surface, from the original paraboloid to its final shape, was always less than 3 percent of the aperture diameter. View full abstract»

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    Wide field imaging problems in radio astronomy

    Cornwell, T.J. ; Golap, K. ; Bhatnagar, S.
    Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05). IEEE International Conference on

    Volume: 5
    DOI: 10.1109/ICASSP.2005.1416440
    Publication Year: 2005 , Page(s): v/861 - v/864 Vol. 5

    IEEE Conference Publications

    The new generation of synthesis radio telescopes now being proposed, designed, and constructed face substantial problems in making images over wide fields of view. Such observations are required either to achieve the full sensitivity limit in crowded fields or for surveys. The Square Kilometre Array (SKA Consortium, Tech. Rep., 2004), now being developed by an international consortium of 15 countries, will require advances well beyond the current state of the art. We review the theory of synthesis radio telescopes for large fields of view. We describe a new algorithm, W projection, for correcting the non-coplanar baselines aberration. This algorithm has improved performance over those previously used (typically an order of magnitude in speed). Despite the advent of W projection, the computing hardware required for SKA wide field imaging is estimated to cost up to $500M (2015 dollars). This is about half the target cost of the SKA. Reconfigurable computing is one way in which the costs can be decreased dramatically. View full abstract»

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    Beamformer design for radio astronomical phased array feeds

    Elmer, M. ; Jeffs, B.D.
    Acoustics Speech and Signal Processing (ICASSP), 2010 IEEE International Conference on

    DOI: 10.1109/ICASSP.2010.5496212
    Publication Year: 2010 , Page(s): 2790 - 2793
    Cited by:  Papers (3)

    IEEE Conference Publications

    A major research emphasis in current radio astronomy instrument development is the use of phased array feeds (PAF) to provide radio telescopes with larger fields of view. Statistically optimal beamformers have been shown to provide high sensitivity for PAFs, however, inability to precisely control beampattern details (even in sidelobes) is problematic. Enforcing beampattern structure with a deterministic beamformer is useful. A hybrid beamforming approach is presented in this paper, which offers the best in sensitivity for a desired amount of beampattern control. Designing any beamformer with simulated calibration data is inadequate for PAF operation and introduces distortion in the final beampattern. A transformation step is required to reduce such effects. View full abstract»

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    IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450)


    Antennas and Propagation Society International Symposium, 2003. IEEE

    Volume: 1
    DOI: 10.1109/APS.2003.1217385
    Publication Year: 2003

    IEEE Conference Publications

    The following topics are dealt with: integral equation methods; spatial processing; metamaterials; antennas for radio telescopes; genetic algorithms; active integrated antennas; microstrip antennas; array antennas; electrically small antennas; FDTD; wavelets and adaptive techniques in electromagnetics; reconfigurable antennas; handset antennas; inverse scattering and imaging; rough surface scattering; numerical analysis of circuits and waveguides; advanced finite methods in electromagnetics; microwave transmission lines; ionospheric sounding; wire antennas; WLAN applications; optimization methods; wave propagation in complex indoor environment; FE methods; subsurface sensing techniques; broadband microstrip patch antennas; spaceborne antennas and feeds; EBG surfaces; MIMO wireless communications; slot and meanderline antennas; guided wave structures; reflector antennas; frequency selective surfaces; wireless networks; wideband microstrip antennas; Bluetooth antenna applications; geometric methods for discrete electromagnetics; leaky-wave antennas; waveguide antennas/filters; multiband antennas; radar imaging; material characterization; DOA estimation; printed reflectarray antennas; electromagnetic education; EMI measurements; dielectric and microwave circuit resonators; time domain integral equation and transient fields; ultra-wideband antennas; diversity, smart and base-station antennas for mobile wireless communication; circularly polarized antennas; microstrip feed networks; waveguide slot arrays; lightning effects in upper atmosphere; medical applications; electromagnetic theory; large finite arrays and periodic structures; dielectric measurements; method of moments basis functions; adaptive processing; fractal antennas; nonlinear electromagnetics; radomes; chiral, ferromagnetic, and random media scattering; cavity backed antennas; horn and dielectric lens antennas; microstrip antenna arrays; urban propagation; terrestrial propagation. View full abstract»

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    Application of robust Capon beamforming to radio astronomical imaging

    van der Tol, S. ; van der Veen, A.-J.
    Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP '05). IEEE International Conference on

    Volume: 4
    DOI: 10.1109/ICASSP.2005.1416202
    Publication Year: 2005 , Page(s): iv/1089 - iv/1092 Vol. 4
    Cited by:  Papers (1)

    IEEE Conference Publications

    Radio telescopes based on large phased arrays form an interesting application area for array signal processing. LOFAR is a large low frequency (10-240 MHz) array consisting of 13,000 antennas grouped into 50 stations, currently under construction in the Netherlands. Data from a 60-element test station for LOFAR is available to evaluate the performance of calibration and imaging algorithms. We apply the robust Capon beamformer (RCB) to make images of the sky from measured data, and compare them to classical Fourier-based images. The RCB takes uncertainty in the calibration into account. Instead of the usual spherical uncertainty sets, we have also derived a more constrained uncertainty set specifically for imaging with the RCB. The results are images with a higher dynamic range than classical or Capon beamforming. Additional simulations confirm that the images are more accurate. View full abstract»

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    S-band octave-bandwidth orthomode transducer for the Expanded Very Large Array

    Coutts, G.M. ; Dinwiddie, H. ; Lilie, P.
    Antennas and Propagation Society International Symposium, 2009. APSURSI '09. IEEE

    DOI: 10.1109/APS.2009.5172251
    Publication Year: 2009 , Page(s): 1 - 4
    Cited by:  Papers (6)

    IEEE Conference Publications

    The Expanded Very Large Array (EVLA) project is currently under way to upgrade the Very Large Array (VLA) to improve the sensitivity, bandwidth, spectral resolution and frequency coverage of the existing array of 27 radio telescopes. The EVLA receivers will provide continuous frequency coverage from 1 GHz to 50 GHz. Three of the cryogenically cooled EVLA receivers will provide octave band coverage for the L-band (1 GHz to 2 GHz), S-Band (2 GHz to 4 GHz) and C-band (4 GHz to 8 GHz). View full abstract»

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    A wide-band prime-focus horn for low-noise receiver applications

    Thomas, B.M. ; Greene, K.J. ; James, G.L.
    Antennas and Propagation, IEEE Transactions on

    Volume: 38 , Issue: 11
    DOI: 10.1109/8.102759
    Publication Year: 1990 , Page(s): 1898 - 1900
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    A horn suitable for a prime-focus antenna requiring low cross polarization, wide bandwidth, and low spillover is described. The design is particularly suited for low-noise applications such as high-quality satellite earth-station antennas and radio telescopes. The horn has a return loss substantially better than 20 dB, a cross polar sidelobe level better than -20 dB, a beamwidth variation of 40% and negligible phase center shift View full abstract»

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    Non-periodic arrays for radio-astronomy applications

    Gonzalez-Ovejero, D. ; de Lera Acedo, E. ; Razavi-Ghods, N. ; Craeye, C. ; Garcia Munoz, L.E.
    Antennas and Propagation (APSURSI), 2011 IEEE International Symposium on

    DOI: 10.1109/APS.2011.5996835
    Publication Year: 2011 , Page(s): 1762 - 1765
    Cited by:  Papers (7)

    IEEE Conference Publications

    The exploitation of non-periodic antenna arrays for next-generation radio-telescopes is evaluated in the present work. More precisely, the radiation properties and the mutual coupling effects in such structures are studied. A special-purpose Method-of-Moments (MoM) simulation technique allows us to obtain all the Embedded Element Patterns (EEP) and the array impedance matrix, while estimating the effects of mutual coupling in very large arrays. The level of averaging of mutual-coupling effects is analyzed in terms of array patterns and the more difficult case of deterministic nulling in presence of mutual coupling is exposed. View full abstract»

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    Beamforming and interference canceling with very large wideband arrays

    Ellingson, S.W.
    Antennas and Propagation, IEEE Transactions on

    Volume: 51 , Issue: 6
    DOI: 10.1109/TAP.2003.812237
    Publication Year: 2003 , Page(s): 1338 - 1346
    Cited by:  Papers (6)  |  Patents (1)

    IEEE Journals & Magazines

    Future radio telescopes are envisioned to be beamforming arrays containing hundreds to millions of elements distributed over thousands of km2, with bandwidths that are 10% or more of the RF center frequency. It is awkward to analyze such systems using traditional narrowband beamforming theory. This paper presents a frequency-domain model that includes relevant features such as true time delay, distributed Doppler effects, and nonideal instrumental frequency response. Conventional beamforming - i.e., maximizing the gain in a certain direction subject to no other constraints - is analyzed in the context of the model. A simple method for suppressing interference in the beamformer output is also analyzed. In this method, a second beam is formed in the direction of the interference and subtracted from the output of the desired beam. Although the concept is sound, two problems are identified. First is the potential for partial or complete canceling of the desired source, along with the interference. The second problem is coloring of the noise spectrum, which may thwart the detection of weak spectral features. These problems are shown to be closely related to the array geometry, and some workarounds are suggested. View full abstract»

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    The quadruple-ridged flared horn: A flexible, multi-octave reflector feed spanning f/0,3 to f/2.5

    Akgiray, A. ; Weinreb, S. ; Imbriale, W.A.
    Antennas and Propagation (EuCAP), 2013 7th European Conference on

    Publication Year: 2013 , Page(s): 768 - 769

    IEEE Conference Publications

    In this paper, we present four quadruple-ridged flared horn designs achieving 6-1 frequency bandwidth with good match and near-constant beamwidth in E- and D-planes. Nominal 10 dB beamwidths of the designs range from 32 to 115 degrees. Such design flexibility makes the quad-ridge horn a very attractive reflector antenna feed candidate, especially for next generation radio telescopes. View full abstract»

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    Bandwidth limits of beamforming networks for low-noise focal-plane arrays

    Veidt, B. ; Dewdney, P.
    Antennas and Propagation, IEEE Transactions on

    Volume: 53 , Issue: 1 , Part: 2
    DOI: 10.1109/TAP.2004.838781
    Publication Year: 2005 , Page(s): 450 - 454
    Cited by:  Papers (5)

    IEEE Journals & Magazines

    Future radio telescopes will use arrays of closely-spaced antenna elements at the focal plane. The outputs from the elements will feed a beamforming network which will produce multiple beams. With a simple beamforming network the weights applied to the element outputs will be independent of frequency, resulting in a frequency-dependent feed pattern. We show, with results from numerical simulations, that the signal-to-noise ratio of a focal-plane array will be degraded with moderate bandwidths. We also briefly discuss ways to mitigate this effect. View full abstract»

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    Tracking and communication means developed at the Special Mechanical Engineering Design Office

    Himmelman, V.G. ; Kuchinsky, G.S.
    Antenna Theory and Techniques, 2003. 4th International Conference on

    Volume: 1
    DOI: 10.1109/ICATT.2003.1239152
    Publication Year: 2003 , Page(s): 68 - 70 vol.1

    IEEE Conference Publications

    A brief review of the Special Mechanical Engineering Design Office activities in the sphere of tracking and communication means development optical and radio telescopes - having, from the 50-s of the last century, provided for the implementation practically, of all the space studies and programs in the USSR, has been given in the report. The data on the problem trends in relevancy over the recent years has been given. View full abstract»

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    Mahanaxar: Quality of service guarantees in high-bandwidth, real-time streaming data storage

    Bigelow, D. ; Brandt, S. ; Bent, J. ; Chen, H.B.
    Mass Storage Systems and Technologies (MSST), 2010 IEEE 26th Symposium on

    DOI: 10.1109/MSST.2010.5496975
    Publication Year: 2010 , Page(s): 1 - 11
    Cited by:  Papers (1)

    IEEE Conference Publications

    Large radio telescopes, cyber-security systems monitoring real-time network traffic, and others have specialized data storage needs: guaranteed capture of an ultra-high-bandwidth data stream, retention of the data long enough to determine what is “interesting,” retention of interesting data indefinitely, and concurrent read/write access to determine what data is interesting, without interrupting the ongoing capture of incoming data. Mahanaxar addresses this problem. Mahanaxar guarantees streaming real-time data capture at (nearly) the full rate of the raw device, allows concurrent read and write access to the device on a best-effort basis without interrupting the data capture, and retains data as long as possible given the available storage. It has built in mechanisms for reliability and indexing, can scale to meet arbitrary bandwidth requirements, and handles both small and large data elements equally well. Results from our prototype implementation show that Mahanaxar provides both better guarantees and better performance than traditional file systems. View full abstract»

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    Minimization of the plane-wave scattering contribution of inverted-Y strut tripods to the noise temperature of reflector antennas

    Moreira, F.J.S. ; Prata, A., Jr ; Thorburn, M.A.
    Antennas and Propagation, IEEE Transactions on

    Volume: 44 , Issue: 4
    DOI: 10.1109/8.489300
    Publication Year: 1996 , Page(s): 492 - 499
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    The article is concerned with determining the metallic strut cross section of inverted-Y tripods used to minimize the plane-wave scattering contribution to the noise temperature of ground-station reflector antennas and radio telescopes. This is accomplished by numerically optimizing the cross section for minimum ground-noise pickup over the antenna elevation-angle operation range. Advantage is taken of the fact that although the struts' cross-section perimeter can be comparable to the operation wavelength, their electrical lengths are usually long. This allows the struts' scattering characteristics to be determined by solving standard two-dimensional field integral equations. The article concentrates on the top strut of an inverted-Y configuration since it is responsible for the dominant ground noise pickup associated with the plane-wave scattering. Numerical simulations are presented to substantiate this fact and a simple and convenient broadband closed-form representation for the minimum-noise top-strut cross section is derived and tested View full abstract»

  • Open Access

    Geometry Design Optimization of Large-Scale Broadband Antenna Array Systems

    El-Makadema, A. ; Rashid, L. ; Brown, A.K.
    Antennas and Propagation, IEEE Transactions on

    Volume: 62 , Issue: 4 , Part: 1
    DOI: 10.1109/TAP.2013.2272571
    Publication Year: 2014 , Page(s): 1673 - 1680

    IEEE Journals & Magazines

    The next generation radio telescopes such as the Square Kilometer Array (SKA) are expected to contain thousands of antenna array elements operating over a broad frequency range where the signals from each antenna element are combined and processed simultaneously providing high sensitivity with multiple beams providing a wide field of view. One crucial design aspect influencing both the performance and the cost of such systems is the array geometry. Due to the large bandwidth and number of broadband antenna elements, the optimization of such array system is difficult to achieve with the current array geometry optimization techniques which rely mainly on genetic algorithms and pattern search techniques. This paper provides a study of the effects of array geometry on the performance broadband array system. In addition, it provides a method where the array geometry can be more easily optimized for different applications. This is demonstrated for optimizing a typical SKA station in the frequency band between (70-450 MHz). View full abstract»

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    Dynamics analysis of a redundant parallel manipulator driven by elastic cables

    Bedoustani, Y.B. ; Taghirad, H.D. ; Aref, M.M.
    Control, Automation, Robotics and Vision, 2008. ICARCV 2008. 10th International Conference on

    DOI: 10.1109/ICARCV.2008.4795575
    Publication Year: 2008 , Page(s): 536 - 542

    IEEE Conference Publications

    In this paper the dynamic analysis of a cable-driven parallel manipulator is studied in detail. The manipulator architecture is a simplified planar version adopted from the structure of large adaptive reflector (LAR), the Canadian design of next generation giant radio telescopes. This structure consists of a parallel redundant manipulator actuated by long cables. The dynamic equations of this structure are nonlinear and implicit. Long cables, large amounts of impelling forces and high accelerations raise more concern about the elasticity of cables during dynamic analysis, which has been neglected in the preceding works. In this paper, the kinematic analysis of such manipulator is illustrated first. Then the nonlinear dynamic of such mechanism is derived using Newton-Euler formulation. Next a simple model for cable dynamics containing elastic and damping behavior is proposed. The proposed model neither ignores longitude elasticity properties of cable nor makes dynamic formulations heavily complicated like previous researches. Finally, manipulator dynamic with cable dynamic is derived, and the cable elasticity effects are compared in a simulation study. The results show significant role of elasticity in a cable-driven parallel manipulator such as the one used in LAR mechanism. View full abstract»

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    Building Correlators with Many-Core Hardware

    van Nieuwpoort, R.V. ; Romein, J.W.
    Signal Processing Magazine, IEEE

    Volume: 27 , Issue: 2
    DOI: 10.1109/MSP.2009.935385
    Publication Year: 2010 , Page(s): 108 - 117

    IEEE Journals & Magazines

    Radio telescopes typically consist of multiple receivers whose signals are cross-correlated to filter out noise. A recent trend is to correlate in software instead of custom-built hardware, taking advantage of the flexibility that software solutions offer.However, the data rates are usually high and the processing requirements challenging. Many-core processors are promising devices to provide the required processing power. In this article, we explain how to implement and optimize signal-processing applications on multicore CPUs and many-core architectures, such as the Intel Core i7, NVIDIA and ATI graphics processor units (CPUs), and the Cell/BE. We use correlation as a running example. The correlator is a streaming, possibly real-time application, and is much more input/ output (I/O) intensive than applications that are typically implemented on many-core hardware today. We compare with the LOFAR production correlator on an IBM Blue Gene/P (BG/P) supercomputer. We discuss several important architectural problems which cause architectures to perform suboptimally, and also deal with programmability. View full abstract»

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    Solar Modal Structure of the Engineering Environment

    Thomson, D.J. ; Lanzerotti, L.J. ; Vernon, F.L. ; Lessard, Marc R. ; Smith, L.T.P.
    Proceedings of the IEEE

    Volume: 95 , Issue: 5
    DOI: 10.1109/JPROC.2007.894712
    Publication Year: 2007 , Page(s): 1085 - 1132
    Cited by:  Papers (8)

    IEEE Journals & Magazines

    This paper describes some unanticipated effects of the normal modes of the sun on engineering and scientific systems. We begin with historical, scientific, and statistical background, then present evidence for the effects of solar modes on various systems. Engineering evidence for these modes was first noticed in an investigation of communications satellite failures and second in a study of excessive dropped calls in cellular phone systems. The paper also includes several sections on multitaper estimates of spectra, canonical coherences, robust, and cyclostationary variants of multitapering, and related statistical techniques used to separate the various components of this complex system. In our attempt to understand this unexpected source of problems, we have found that solar modes are detectable in the interplanetary magnetic fields and energetic particles at the Ulysses spacecraft, five astronomical units from the Earth. These modes couple into the magnetosphere, the ionosphere, the geomagnetic field, and atmospheric pressure. Estimates of the power spectrum of data from solar radio telescopes and induced voltages on ocean cables show what appear to be solar modes at both lower and higher frequencies than the optically measured solar p-modes. Most surprisingly, these modes are easily detected in seismic data, where they literally shake the Earth. View full abstract»

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    Sensitivity performance of several mappings in shaped offset Gregorian reflectors

    de Villiers, D.I.L. ; Lehmensiek, R.
    Antennas and Propagation Society International Symposium (APSURSI), 2014 IEEE

    DOI: 10.1109/APS.2014.6905064
    Publication Year: 2014 , Page(s): 1477 - 1478
    Cited by:  Papers (3)

    IEEE Conference Publications

    The sensitivity performance of several primary pattern to aperture field mappings in shaped offset Gregorian reflector systems is investigated. Specific attention is given to high efficiency mappings with low second side-lobe levels, as these are of interest in the design of sensitive radio telescopes where the first side-lobe is imaged in the point spread function. Comparisons are made between the predicted analytical illumination efficiencies and the side-lobe levels, as well as the physical optics simulated sensitivity of the systems. The results show that the analytical trends are closely followed in actual shaped systems of moderate electrical size. Some graphs are given showing areas of maximum sensitivity for a specified side-lobe level in the shaping parameter space. View full abstract»

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    Evaluation of an electronic sky derotation scheme for a phased array fed reflector antenna

    Young, A. ; Warnick, K.F. ; Davidson, D.B.
    Antennas and Propagation (EuCAP), 2014 8th European Conference on

    DOI: 10.1109/EuCAP.2014.6902303
    Publication Year: 2014 , Page(s): 2409 - 2413

    IEEE Conference Publications

    In recent years a number of reflector antenna radio telescopes have been fitted with Phased Array Feeds (PAF) [1], [2], [3], [4] as part of ongoing research on the development as well as the effective use of this technology. The baseline design for SKA phase 1 also specifies the use of this technology in the SKA-survey instrument [5]. One major advantage of using a PAF is that it significantly improves the survey speed due to an increase in the Field-of-View (FoV) as multiple beams on the sky may be formed simultaneously. In addition to this, the beamforming capability of such systems also offer the advantage of being able to optimize various Figures-of-Merit (FoM). This ability is often utilized to improve the stability of the beam response over the FoV in order to improve imaging dynamic range [6], [7], [8]. View full abstract»

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    Reconstruction algorithm applied to low-frequency array (LOFAR) image

    Mu-Min Chiou ; Jean-Fu Kiang
    Electromagnetics, Applications and Student Innovation (iWEM), 2011 IEEE International Workshop on

    DOI: 10.1109/iWEM.2011.6021486
    Publication Year: 2011 , Page(s): 217 - 219

    IEEE Conference Publications

    The exploration on Universe has always been a human heritage, and is tightly related to the evolution of science and technology. The use of radio telescopes dated back in the middle of the twentieth century widely open the spectrum of human sensibility. Many different phenomena never known before have been unveiled and further promote our knowledge about the universe. A simulation of image reconstruction algorithm applied to telescopes in visible light is present in this paper. View full abstract»

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    Advances in Calibration and Imaging Techniques in Radio Interferometry

    Rau, U. ; Bhatnagar, S. ; Voronkov, M.A. ; Cornwell, T.J.
    Proceedings of the IEEE

    Volume: 97 , Issue: 8
    DOI: 10.1109/JPROC.2009.2014853
    Publication Year: 2009 , Page(s): 1472 - 1481
    Cited by:  Papers (24)

    IEEE Journals & Magazines

    This paper summarizes some of the major calibration and image reconstruction techniques used in radio interferometry and describes them in a common mathematical framework. The use of this framework has a number of benefits, ranging from clarification of the fundamentals, use of standard numerical optimization techniques, and generalization or specialization to new algorithms. View full abstract»

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    Development of a low-noise wide-band phased-array feed

    Veidt, B. ; Burgess, T. ; Messing, R. ; Hovey, G.J. ; Smegal, R.J.
    General Assembly and Scientific Symposium, 2011 XXXth URSI

    DOI: 10.1109/URSIGASS.2011.6123729
    Publication Year: 2011 , Page(s): 1 - 4

    IEEE Conference Publications

    Low-noise phased-array feeds are a new way to expand the field of view of radio telescopes at centimetre wavelengths. First generation engineering demonstrators of this technology have been constructed and tested by several institutes worldwide. The development of second-generation phased-array feeds is now underway. We describe one effort to design and build an astronomy-capable phased-array feed using techniques to reduce front-end noise and increase system bandwidth. View full abstract»

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    Development of Cryogenic IF Low-Noise 4-12 GHz Amplifiers for ALMA Radio Astronomy Receivers

    Lopez-Fernandez, I. ; Puyol, J.D.G. ; Gonzalez, C.D. ; Cancio, A.B.
    Microwave Symposium Digest, 2006. IEEE MTT-S International

    DOI: 10.1109/MWSYM.2006.249788
    Publication Year: 2006 , Page(s): 1907 - 1910
    Cited by:  Papers (5)

    IEEE Conference Publications

    We describe the design and results of a wide band C-X cryogenic IF amplifier developed for band 9 (602-720 GHz) of ALMA radio telescopes. A cryogenic 4-12 GHz isolator is used at the input to improve matching. Several units have been fabricated and its results are presented. The amplifiers utilize HRL InP transistors to achieve a noise temperature of 5.3 K (0.08 dB NF) on average. Gain fluctuations are critical for the project. Values of Allan variance lower than 4.1 10-9 (0.1 s les T les 10 s) have been obtained View full abstract»

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    Easy to fabricate feeds for astronomical receivers

    Yassin, G. ; Leech, J. ; Tan, B.K. ; Kittara, P.
    Antenna Technology (iWAT), 2013 International Workshop on

    DOI: 10.1109/IWAT.2013.6518288
    Publication Year: 2013 , Page(s): 15 - 18

    IEEE Conference Publications

    Modern ground-based radio-telescopes have stringent requirements on the receiver's feed-horn performance. These include a bandwidth covering a full atmospheric window from good sites (~ 30%), low cross polarization and high beam circularity. In addition the unprecedented sensitivity required by recent proposed experiments requires large format focal plane arrays consisting of a large number of high performance feeds. While these feeds are straightforward to fabricate at microwave frequencies, the tight tolerances required in the THz region makes the realization of a large format array both expensive and time consuming. In this paper we describe feed designs that can be fabricated cheaply and rapidly without compromising the science requirements within the operating bandwidth. We present simulated and measured far-field beam patterns showing low sidelobe levels, good beam circularity and low cross-polarization levels over a fractional bandwidth of 20%. Having demonstrated the efficacy of our horn designs and fabricating technique experimentally, we have designed, fabricated and tested a prototype focal plane array of 37 hexagonally close packed horns milled in a single block of aluminum. Experimental testing of the radiation patterns of the array feeds demonstrated that they were essentially identical to the patterns of the feeds fabricated individually and that cross coupling between adjacent feeds was negligible. View full abstract»

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    Micro-machining in submillimeter-wave circuits

    Rutledge, D.
    Microwave Symposium Digest, 1996., IEEE MTT-S International

    Volume: 3
    DOI: 10.1109/MWSYM.1996.512315
    Publication Year: 1996 , Page(s): 1889 - 1892 vol.3
    Cited by:  Papers (1)

    IEEE Conference Publications