Demonstration of a Broadband Very Long Baseline Interferometer System: A New Instrument for High‐Precision Space Geodesy

Abstract

A prototype broadband geodetic very long baseline interferometry system has been implemented, and measurements of the baseline length over approximately two years, between December 2014 and January 2017, have been made in the process of exercising the system, developing operational procedures, and assessing geodetic precision for the new broadband observing concept. In addition to developing a broadband signal chain and installing the instrumentation on both a new 12-m antenna at the Goddard Geophysical and Astrophysical Observatory and the 18-m Westford antenna at the Massachusetts Institute of Technology Haystack Observatory, it was necessary to develop new correlation and analysis procedures to process the four-band, dual-linear-polarization data. A geodetic analysis of the data from 19 sessions that were observed during this period yielded a weighted root-mean-square deviation of the baseline length residuals about the weighted mean of 1.6 mm. These results validate several of the expectations set forth for the vision of the next-generation geodetic very long baseline interferometry system. Derome, M., et al. (2018). Demonstration of a broadband very long baseline interferometer system: A new instrument for high-precision space geodesy.

Statistical Analysis of the Results of 20 Years of Activity of the International VLBI Service for Geodesy and Astrometry

“…In 2015, an international network of stations operating according to the new technology standard VLBI2010 (Behrend et al, 2009) began to work. At first, it was two stations, GGAO12M (Maryland, USA) and WESTFORD (Massachusetts, USA), on which new equipment and observation technology were tested (Niell et al, 2018). In 2016-2017, antennas KOKEE12M (Hawaii, USA), WETTZ13S (one of the two new antennas at the Wettzell station, Germany), RAEGYEB (Yebes, Spain), ISHIOKA (Ishioka, Japan), and ONSA13NE (one of the two new antennas at the Onsala station, Sweden) were added to this network.…”

“…Until the 1980s, VLBI data were used to determine the EOP irregularly. A review of early efforts in determining the EOP by the VLBI method before the early 1980s can be found, for example, in Blinov (1983); Moritz and Mueller (1987). The first special observing programs for determination of the EOP were the POLARIS program of the US Geodetic Survey (146 sessions from November 1980 to November 1990) and the JPL's TEMPO program (from the middle of 1980).…”

Wideband single pixel feed system over 4.6–24 GHz for the Square Kilometre Array

“…In the results shown below, the measured Band B feed beam pattern was used in the system simulator to illuminate the reflector geometry. The Band B feed design has predicted aperture efficiency, η a , in the SKA reflector better than 78 %, 70 %, 65 %, and 60 % over frequency intervals 4.6-8 GHz, [8][9][10][11][12][13][14][15][15][16][17][18][19][20] GHz, and 20-24 GHz respectively. The vertical polarization on the reflector show slightly lower efficiency.…”

“…In Fig. 5, the predicted aperture efficiency using measured feed beam patterns from Band B is presented for the shaped SKA reflector as well as for the SKA precursor reflector DVA [12], and the VGOS reflector (unshaped) for next generation of geodetic VLBI stations [13]. All three reflectors have similar half-subtended angle (SKA: θ e =58 • ) and the ∼10 % reduction of η a in the VGOS reflector is because it is unshaped.…”

Optimizing schedules for the VLBI global observing system

“…The VLBI Global Observing System (VGOS) as the nextgeneration VLBI system is necessary to reach the goal of the Global Geodetic Observing System (GGOS) (Plag and Pearlman 2009) of providing station coordinates with an accuracy of 1 mm and velocities of 0.1 mm per year (Niell et al 2005;Petrachenko et al 2009). Many studies did test different scheduling strategies for VGOS, like a source-based B Matthias Schartner matthias.schartner@geo.tuwien.ac.at 1 Department of Geodesy and Geoinformation, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria scheduling approach (Sun et al 2014) or dynamic scheduling (Lovell et al 2014;Iles et al 2018).…”