A5106627271- GNSS positioning and interference
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Ionosphere and magnetosphere dynamics
- Astrophysics and Cosmic Phenomena
- Antenna Design and Optimization
- Integrated Circuits and Semiconductor Failure Analysis
- Advancements in PLL and VCO Technologies
- Solar and Space Plasma Dynamics
- Satellite Communication Systems
- Advanced MIMO Systems Optimization
- Inertial Sensor and Navigation
- Radio Wave Propagation Studies
- Planetary Science and Exploration
- CCD and CMOS Imaging Sensors
- Image and Signal Denoising Methods
- Space Exploration and Technology
- Industrial Vision Systems and Defect Detection
- Scientific Research and Discoveries
- VLSI and Analog Circuit Testing
- Spacecraft Design and Technology
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Advanced Wireless Communication Techniques
Massachusetts Institute of Technology
1981-2021
Northeast Radio Observatory Corporation
1982-2021
Center for Astrophysics Harvard & Smithsonian
2010
Curtin University
2010
Harvard University Press
2010
The University of Melbourne
2010
Planetary Science Institute
1981
The Mark III very-long-baseline interferometry (VLBI) system allows recording and later processing of up to 112 megabits per second from each radio telescope an interferometer array. For astrometric geodetic measurements, signals two radio-frequency bands (2.2 2.3 8.2 8.6 gigahertz) are sampled recorded simultaneously at all antenna sites. From these dual-band recordings the relative group delays arriving pair sites can be corrected for contributions due ionosphere. many sources which...
An orbiting spacecraft and ground observatories have been used to obtain interferometric observations of cosmic radio sources. The Tracking Data Relay Satellite System (TDRSS) was as the observatory in conjunction with two 64- meter telescopes at observatories, one Australia Japan. quasars 1730-130 (NRAO 530), 1510-089, 1741-038 were observed a frequency 2.3 gigahertz, maximum projected baseline 1.4 earth diameters achieved. All quasar for which valid data acquired resulted detected fringes....
Abstract A prototype broadband geodetic very long baseline interferometry system has been implemented, and measurements of the length over approximately two years, between December 2014 January 2017, have made in process exercising system, developing operational procedures, assessing precision for new observing concept. In addition to a signal chain installing instrumentation on both 12‐m antenna at Goddard Geophysical Astrophysical Observatory 18‐m Westford Massachusetts Institute...
view Abstract Citations (55) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS 15 GHz Space VLBI Observations Using an Antenna on a TDRSS Satellite Linfield, R. P. ; Levy, G. S. Edwards, C. D. Ulvestad, J. Ottenhoff, H. Hirabayashi, Morimoto, M. Inoue, Jauncey, L. Reynolds, Nishimura, T. Hayashi, Takano, Yamada, Barrett, W. Conner, Heflin, B. Lehar, Burke, F. Roberts, Whitney, A. Cappallo, Rogers, E. Pospieszalski, Dinardo, Skjerve, Stavert,...
view Abstract Citations (61) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The nucleus of M 81 : simultaneous 2.3 and 8.3 GHz Mark III VLBI observations. Bartel, N. ; Shapiro, I. Corey, B. E. Marcaide, J. M. Rogers, A. Whitney, R. Cappallo, Graham, D. Romney, Preston, very long baseline interferometry (VLBI) observations have been made the in normal galaxy M81 (NGC 3031) simultaneously at GHz, it was found that nearly 100% flux density...
Very Long Baseline Interferometry (VLBI) is a primary space-geodetic technique for determining precise coordinates on the Earth, monitoring variable Earth rotation and orientation with highest precision, deriving many other parameters of system. The International VLBI Service Geodesy Astrometry (IVS, http://ivscc.gsfc.nasa.gov/) service Association (IAG) Astronomical Union (IAU). datasets published here are results individual sessions in form normal equations SINEX 2.0 format...
The Mark 4 VLBI correlator is a station‐based system designed to process data from up 16 stations at an aggregate rate of 1 Gbps/station. It compatible with recorded on 3A, 4, and VLBA tape‐based data‐acquisition systems, as well the new disc‐based 5 which also supports both real‐time quasi‐real‐time data‐transmission over high‐speed networks. incorporates XF algorithm implemented in custom‐VLSI chip that can be flexibly configured cross‐correlate one four baselines single 2‐bits/sample...
view Abstract Citations (28) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS VLBI Using a Telescope in Earth Orbit. I. The Observations Levy, G. S. ; Linfield, R. P. Edwards, C. D. Ulvestad, J. Jordan, F., Jr. Dinardo, Christensen, Preston, A. Skjerve, L. Stavert, Burke, B. F. Whitney, Cappallo, Rogers, E. Blaney, K. Maher, M. Ottenhoff, H. Jauncey, Peters, W. Reynolds, Nishimura, T. Hayashi, Takano, Yamada, Hirabayashi, Morimoto, Inoue,...
Euler's equations of motion, modified to include elasticity and solid friction, were used study the rotation moon. Two heuristic models for anelasticity considered: Q independent frequency inversely proportional strain oscillation. Parameters in each model estimated by weighted least squares from 9 years lunar laser range observations. The root mean square postfit residuals was 19 cm case. For a period 1 month, estimates obtained with two similar surprisingly low: 23 ± 6. uncertainty, ±6,...
This paper describes a correlator that is optimized for the Xilinx Virtex-4 SX FPGA, and its application in SKAMP radio telescope at Molonglo Radio Observatory. The digital backend of consists more than 800 FPGAs. Correlation performed between each every pairing antenna inputs, so telescope, with 384 has approximately 74,000 correlations; 100 MHz input bandwidth from this requires real-time processing 7 tera complex multiply-accumulates per second. correlation cell described takes advantage...
We present the first results from a long-term program to measure trigonometric parallaxes and proper motions of set pulsars using VLBI. obtained these for PSR B2021+51 four sessions S-band observations pulsar associated reference sources. estimate parallax 0.95 ± 0.37 mas, motion μα = -8.11 0.24 mas yr-1 μδ +13.41 0.25 yr-1, position at epoch 1992.723 α 20h22m4987031 000004 δ 51°54'502913 00003 (all J2000). Our implies an average electron density 0.021 0.008 cm-3 along line sight pulsar....
Abstract We measured the components of 31-m-long vector between two very-long-baseline interferometry (VLBI) antennas at Kokee Park Geophysical Observatory (KPGO), Hawaii, with approximately 1 mm precision using phase delay observables from dedicated VLBI observations in 2016 and 2018. The KPGO are 20 m legacy antenna 12 Global Observing System (VGOS) antenna. Independent estimates were obtained by National Geodetic Survey (NGS) standard optical surveys 2015 uncertainties latter survey 0.3...
A magnetic tape recorder developed for the special requirements of radio astronomy and geodesy is described. These include a high bit packing density long record times. The current version this longitudinal used by Very Long Baseline Array (VLBA) records 5.5 Terabits on 14-in diameter reel inch-wide tape. maximum rate 256 Mb/s achieved in VLBA configuration with one operating at 4 ms utilizing 32 heads single stack. recorders have been tested using 2.25 fr/ mu m (57.15 kfrpi); 448 data +56...
It is shown that the excellent Murchison Radio-astronomy Observatory site allows Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities form images in FM radio band.The techniques described are running autonomously our calibration imaging software, which currently being used process an FM-band survey of entire southern sky.
Abstract This article focuses on the new generation of geodetic very long baseline interferometry (VLBI), VLBI global observing system (VGOS), and measurements carried out during CONT17 campaign. It uses broadband technology that increases both number precision observations. These characteristics make VGOS a suitable tool for studying atmosphere. study effects ionosphere signals using model incorporates extends ideas originally published in Hobiger et al. (2006,...