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Haystack VLBI updates


16 JUL 2018   One of the test components of the ETU (Engineering Test Unit). The ETU, in the testing process at the Westford technical lab, contains a subset of the signal chain and once installed, will allow engineers to test an antenna's pointing capability earlier in the process than was previously possible.

ETU test component
29 JUN 2018   The signal chain progress continues; today we see a couple of the (meticulously organized!) staging areas for various components in the build process. Included here are some of the innards of the CDMS, or cable delay measurement system, that will be installed on the new VGOS antenna at McDonald. The CDMS, which was also successfully deployed at KPGO, is designed by Haystack to measure variations of the delay in the cable carrying the reference frequency from the hydrogen maser to the phase calibration generator. The CDMS design corrects for transmission of the reference frequency over an optical fiber or coaxial cable. The cable delay value is an essential component of the final geodetic estimation. The phase cal board is mid-installation in the top photo; in the bottom image is one of the gear couplings (hand model: Larry).

CDMS being built  

gear coupling

22 JUN 2018  The RDBEs (ROACH Digital Backend System) are looking good, as seen in one of the Haystack technical laboratories yesterday! Several of these RDBEs are destined for the next VGOS site, located at McDonald Observatory in Texas.

RDBE, or ROACH Digital Back End
18 JUN 2018   Last week, we said farewell to the ETU Vibration Monitoring System, but we took a few photos before it went out the door. Destined for the new VGOS antenna at McDonald, Texas, by way of Goddard, the ETU Vibration Monitoring System is a set of very sensitive sensors that use accelerometers to measure any vibration on the antenna's dish once they are attached; the accompanying LabVIEW software shows graphs of even tiny motions and logs data to files on a field laptop for McDonald engineers to monitor.

feed horn testing  

testing results

12 JUN 2018   In a collaborative effort between GSFC and MIT Haystack, the radiation pattern of the X-band feed horn for the Engineering Test Unit (ETU) is measured at an antenna test facility within GSFC in Greenbelt, Maryland. The top figure at right shows the setup inside the anechoic chamber; the bottom figure at right, a representative 3D rendition. Below is a plot of the pattern at the VGOS band D frequency of 10.2 GHz. As designed, the corrugated conical horn feed pattern exhibits excellent agreement between E and H plane patterns with very low cross-polarization levels.


testing results

feed horn testing  

testing results

23 MAY 2018   The assembly process for many of the MGO VGOS antenna components is not merely highly photogenic but very carefully organized; once sourced or machined, parts are labeled and arranged for the most efficient and accurate assembly.

Coming up soon is the next stage in their life cycle!

ETU arrival  

ETU arrival

16 MAY 2018 It's only fitting that an image of the accelerometer going into testing is a little shaky. These devices are part of the system that will be located at the new VGOS station at McDonald to monitor antenna vibrations. The testing phase for the accelerometers is designed to ensure highly accurate calibration. ETU arrival  

25 APRIL 2018   Earlier this month, we received the corrugated conical horn feed for the X-band Engineering Test Unit (ETU). The ETU is a 8.2–12.4 GHz room-temperature receiver chain designed and built to test the pointing capability of the 12-meter ISI antenna to be constructed at McDonald Observatory. The engineering department reports that an early check of its impedance match looked good, particularly at VGOS band D frequencies (centered at 10.44 GHz). The ETU build continues! (Photo credit: Ganesh Rajagopalan) ETU arrival  

9 APRIL 2018   A momentous anniversary for VLBI: in April 1968, fifty years ago this month, observations were held between MIT Haystack Observatory and the Onsala Space Observatory in Sweden. We threw VLBI a transatlantic birthday party at Haystack and Onsala, complete with cake, champagne, and Swedish fish! Several scientists and engineers who helped develop this technique attended at both observatories and shared their memories of early VLBI work. Shown here are Alan Whitney, Jim Moran, and Alan Rogers; a Mark I tape from 1968; and today's Haystack VGOS group.

For more on this historic scientific anniversary, see MIT News:

Alan Whitney, Jim Moran, Alan Rogers  

Mark I tape, historic documents  

Haystack VGOS group, 2018  

3 APRIL 2018   The MGO build includes a number of custom parts CNC machined by the experts here in Westford. Here a 3D CAD model is converted from virtual to reality, from the original design drawing, through the machining process, into the finishing stages. The white liquid is a cutting fluid that also cools and flushes out the chipped-out pieces to be discarded from the final product.

Coming soon: VLBI anniversary celebration, plus an update on the ETU (engineering test unit) progress!

MGO CNC machining part, #1  

MGO CNC machining part, #2  

MGO CNC machining part, #3  

MGO CNC machining part, #4  

21 MARCH 2018   QRFH feed in the house! Build progress continues on the NASA SGP VGOS antenna's signal chain, to be located at McDonald Observatory in Texas. The shiny, artwork-quality object shown here is the quad-ridge flared horn (QRFH) feed. This feed is a main component of the cryogenic front end of the antenna's signal chain. The design of the QRFH shown here is optimized for the VGOS 2.3–14 GHz frequency range; it collects radio waves from the 12m antenna's dish (via the subreflector) and converts the signal to an electrical current to be amplified by cooled, ultra-low-noise amplifiers. The ridged and flared design allows for signals to be gathered in dual linear orthogonal polarizations over a 6:1 wide-frequency range. [Feed model QRFH-45-62P3, Cosmic Microwave Technology Inc.; hand model: C. Eckert]

More on the antenna, the low-noise amplifier, and the rest of the front end coming soon!

testing system temperature
7 MARCH 2018 Progress continues on the NASA SGP McDonald VGOS antenna's signal chain; here, the positioner alignment and assembly is nearing completion at the Westford build site. [Photo credit: Michael Poirier] MGO positioner assembly, #1  

MGO positioner assembly, #1

1 MARCH 2018 The signal chain build for the new VGOS antenna at McDonald Observatory in Texas is well underway! The front-end positioner — which houses mechanical and electrical elements such as the antenna feed, receiver payload, receiver cryogenics and vacuum, and calibration and monitoring systems — is nearing completion at the Westford instrumentation facility. [Photo credit: Michael Poirier]


MGO positioner build MGO positioner build

MGO positioner build


MGO positioner build

27 FEBRUARY 2018 Earlier this month, our VLBI/VGOS science and engineering team met with colleagues from NVI and NASA’s Space Geodesy Project (SGP). Haystack and NVI have a long history of successful collaboration on VLBI data and science! Together, we reviewed the VGOS progress over the last few years, and produced a tentative plan for the rollout of the VGOS network that will cover the period between 2018-2020. [In photo: Pedro Elosegui (Haystack), Chester Ruszczyk (Haystack), Dirk Behrend (NVI), Ganesh Rajagopalan (Haystack), Frank Lemoine (NASA/SGP Project Scientist), Ed Himwich (NVI), John Barrett (Haystack), and John Gipson (NVI), at MIT Haystack Observatory] testing system temperature
23 FEBRUARY 2018 Recently, a team from Haystack tested the system temperature of the broadband receiver of the VLBI antenna at Goddard Geophysical and Astronomical Observatory (GGAO), after servicing it and before transporting it back from Westford, Massachusetts, to GGAO, Maryland. This engineer looks cold, but he’s more interested in how the New England weather affected the receiver’s performance (only a few dBs above the noise floor of the spectrum analyzer) than keeping himself warm. The radome in the background houses the Haystack 37-m radio telescope. [Photo credit: Ganesh Rajagopalan]

testing system temperature
21 FEBRUARY 2018 Welcome to the VLBI weblog at MIT Haystack Observatory, where we’ll cover highlights of our latest work in regard to very long baseline interferometry (VLBI), which we use for geodesy and astronomy. We’ll share updates from our Westford radio telescope and some of our collaborations with other VLBI institutions and stations around the world, as well as progress on the signal chain for NASA’s next cutting-edge VGOS station, at McDonald Observatory, Texas—following in the footsteps of the Space Geodesy Project’s popular Koke'e Park Geophysical Observatory (KPGO) Blog.


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