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Progress through Photos
This webpage is devoted to Progress through Photos; as the
construction of the LWDA test station at the VLA develops and sites for other
LWA stations are explored, we will replace older photos with newer ones.
Additional photos may be found on the
LWA Wiki
Mobile Workstation
(November 2008)
The new mobile workstation is being fitted up for operation at
the sites. Thanks to support from the Department of Physics and
Astronomy at UNM, there is now a truck available to tow the
workstation.
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Outside and inside the new LWA Mobile Workstation.
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Trenching
(November 2008)
Trenching between the LWDA site and the RTA site (300m away)
was carried out on November 22. The previous, above-ground cable
had been damaged. The LWDA-RTA interferometer is in continuous
use, so replacement of the cable was necessary. But this work also
enables us to do some measurements of the effects of dispersion
in the cable under the varying environmental conditions, and
gives us experience with the equipment and
procedures for burying cables.
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Making the trench with the trencher; cables from one of the blade antennas goes into the trench.
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The trench goes 1,000 feet from the shelter which is seen in the distance to the LWDA Rapid
Test Array (RTA). The junction box with its cover plate is shown in the foreground;
it is located at 500 feet from the shelter.
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"Brassboard" analog receiver built and tested
(September 2008)
The "Brassboard" Analog Receiver for the LWA was designed at UNM by Joe Craig,
LWA Systems Engineer. Each receiver board/module contains four independent
receive channels. Each channel provides a maximum gain of 80dB, with 60dB of
gain control in 2dB steps, spread out over two digital step attenuators which
balance the receiver's noise figure against linearity performance. The
receiver has a reconfigurable filter bank with three selectable filters; 20
MHz-80 MHz "Full Bandwidth" filter, 28 MHz-54 MHz "Reduced Bandwidth" filter,
and a "Split Bandwidth" filter to provide additional independent gain control
over the low-frequency portion of the spectrum (diplexer split at 32 MHz).
Along with these filters, there is also an "FM Notch" filter to attenuate the
FM band. In addition to gain and filtering, the receiver also has an
integrated Bias-T for powering the Front-End Electronics (FEE) and control
logic for switching on and off the FEE power. The logic interface is standard
TTL/CMOS static I/O interfaced over a ribbon cable.
The spectrum shown is 100ms integration of 200MSPS time data, FFT'd with a RBW
of 30kHz in the "Full Bandwidth" filter configuration. This data was acquired
with the current LWA receive chain at the LWDA/VLA site on Sept. 6th, 2008.
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Joe Craig's brassboard analog receiver and the test spectrum.
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5 LWA sites approved (September 3, 2008)
The FEMA CATegorical EXclusion (CATEX) has been signed and filed. This brings the number of LWA
sites which have satisfied the Federal environmental permit process to 5 (LWDA + 4 with this action).
The completion of the CATEX is a major step forward in the site acquisition.
The accompanying photos shows all 5 sites (as yellow squares) on a partial map of New Mexico and then
photos of the individual sites.
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LWA Programs Operation Director hired.
Dr. Joe Craig was hired at UNM in February 2008
in the position of Programs Operation Director for the Long Wavelength
Array (LWA). Joe is a RF Systems Engineer.
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We welcome Joe Craig, the new Programs Operation Director, to the LWA Project Team.
Joe received his BS in Electrical Engineering from New Mexico Institute of Mining and Technology.
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Virgina Tech and University of Iowa join the LWA Project in July 2007.
LWA Executive Project Director hired.
Dr. Lee J. Rickard was hired at UNM in April 2007
in the position of Executive Project Director for the Long Wavelength
Array (LWA). Lee J. was formerly at the Naval Research Lab,
and is a well respected scientist who has published in both ionospheric
and astronomical journals. Lee J. will be establishing
the LWA Project Office on South Campus at UNM.
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The two LWA Directors - Left: Lee J. Rickard, Executive Project Director and Right: Greg Taylor, Scientific Director - at a party celebrating Lee J.'s arrival.
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Site Testing for LWA Stations
The first overnight RFI testing at potential LWA stations took place
at the VLA North Arm and Magdelena sites during June 25-27, 2007.
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"Campsite" just off the North Arm of the VLA includes a tent, one of the Big Blade antennas plus the new trailer - June 25, 2007.
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As a member of the team to select sites for the LWA stations, UNM graduate student Frank Schinzel is reviewing maps while data on Radio Frequency Interference are being recorded by computer inside the trailer at a location in the northern part of the Plains of St.Augustine in Socorro County. The signals are picked up by the blade antenna in the front right of the picture.
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Testing for radio interference at potential sites for other LWA stations began in December 2006.
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Testing at the Twin Peaks site - located north of US 60 and west of the North arm of the VLA. U-Haul truck with test equipment, big blade antenna infront and power supply equal red item in field to the right. December 15, 2006
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Welcome to the Construction site
The LWDA is a test bed for the development of the LWA - it is located on the VLA site.
During the week of May 14, 2007 an LWA team working with Bill Erickson set up an
outlier antenna to work with the LWDA as an interferometer. The outlier is
the second of the Big Blade antennas currently at the LWDA site (aka BB2)
and is located approximately 300 meters due East of the 16 element LWDA. The
interferometer allows us to achieve high Signal-to-Noise measurements on
many known discrete radio sources. In turn, that allows us to constrain
technical characteristics of the LWDA more accurately than previously
possible, including accurate flux and phase calibration. The interferometer
also brings a new operational mode for targeted source observations, in
addition to the current all-sky monitoring and phased array beam-forming
modes of the LWDA alone. The LWDA and outlier are remotely configurable
between various modes, including with multiple beams, and a number of
innovative science programs are being considered to take advantage of these
capabilities.
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Landscape photo showing the approximate 300 m separation between Big Blade 2
(BB2 - on the left) and the 16 element LWDA (on the right).
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SINE and COSINE interferometer fringes on the bright radio source Cas A at
74 MHz. The operational mode employed was a tracking two element
interferometer between the outlier Big Blade antenna (BB2) and the phased
array LWDA. Each point represents 1 second of data at 1.6 MHz instantaneous
bandwidth.
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The Specmaster Data website lets you view Daily Dynamic Spectra and learn about special events from Big Blade at the LWDA site.
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Commissioning observations made in October 2006 by the Long Wavelength Demonstrator Array (LWDA) highlight its all sky imaging capability. This 24 hour movie (also available in mpg format) is made at a frequency of 73.8 MHz and shows the full sky as visible from the LWDA site in New Mexico. As the sky rotates, emission from the bright sources Cassiopeia A, Cygnus A, and the Sun, as well as the bright regions of the Galactic Plane, are all clearly visible. The Galactic Center region is marked by the position of the Sagittarius A complex. This movie was made by Tracy Clarke (NRL/Interferometrics Inc) using AIPS to process the observations from the LWDA.
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During second half of October 2006 all the hardware was installed at the site, including both polarizations and digital receivers for all the dipoles. Careful phase calibrations were performed and these movies demonstrate how successful they were. Congratulations to all who made this possible.
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LWDA site - 16 dipoles and electronics trailer (right back) with VLA
antennas in the background as photographed in early August 2006.
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| New large blade antenna for testing (photo - August 2006).
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| The first results are displayed
in power point presentations at URSI and AAS in January 2006.
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| Construction of the LWDA began at the VLA site
during the Autumn 2005.
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