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  • josemanuelchavez 9:19 pm on November 24, 2012 Permalink | Reply
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    Day 2.2: Smoko Loco 

    After spending a few hours in the field continuing our efforts on DARE, we decided to take a break, or rather a “smoko” in the local slang.  Normally referring a smoke or tea break, the team bent the meaning to imply a rest from work (maybe some tea).  On a related note, Hamdi’s new rap name is “Smoko Loco”.  We have yet to see if the name will launch the aspiring rap artist to super-stardom.  Stay tuned.

    Hamdi making sure the spectrum analyzer rides comfortably on the way to the site

    Nearby the EDGES/DARE site there is a control building that has a well-equipped lab in addition to some other amenities that one would find on a campus research building.  Along with having a kitchenette and conference room, it also has a designated First-Aid base and a highly monitored wing with dozens of (yet to be) servers.  In order to prevent any RFI (Radio Frequency Interference), the building is protected by two pairs of pneumatic doors.  This makes the building an impenetrable and impermeable signal fortress.

    Set of pneumatic doors

    Hamdi continued working on the system in the lab inside, seemingly running off infinite energy.  After a few tests, he alerted us by calling out, “I found the problem!  It’s alive!”, referring to the balun unit.  The unit was difficult to measure, but by boosting the signal we were able to spot it on the spectrum analyzer.

    Hamdi using the spectrum analyzer

    As the team discussed during the lunch break, unraveling low-frequency radio electronics is not a simple task.  For instance, to use commercially available equipment we must use a single-ended component.  The team uses balun circuits to transform this to a differential (or vice versa).  Test equipment we have on site does not measure differential circuits directly.  This means we need to use some tricks.   Likewise, faint signals provide a problem which requires highly sensitive equipment.   In the end we measured the gain of the balun at 14 dB with an open load.  That sounded about right, so we were ready to reinstall the balun and the antenna.

    Control building

    Refueled and regrouped, the team launched off from the control building and back to DARE.  The winds had beefed up considerably in the afternoon, which made housing and rearranging the somewhat fragile DARE biconical antenna worrying.  So we decided to postpone until the morning.  Comfortable with a good day’s work, the team used the hut as a temporary home for the antenna and strapped down the foam enclosure.

    DARE securely strapped down, dubbed “Scar Face”

    All in all, the team managed to solve a few issues – technical and logistical, alike.  We checked the DARE low noise amplifier, learned how to best arrange our day, and many other things that will help out as a whole.  The team definitely felt more confident after today’s work.

    View outside the control building

    I do have to add that being here reminds me of my childhood summers in Mexico; a foil between scientific investigation and the rugged rancher lifestyle.  The people are both relaxed and excited about spending time at Boolardy (or rather Ball-ah-dee) Station.  It’s a great place to do research and meet pleasant people.

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  • josemanuelchavez 12:32 am on November 24, 2012 Permalink | Reply
    Tags: , , , , , radio   

    Day 2.1: Ready to Roll 'n' Rock 

    On the second day of our problem solving expedition, we began our morning earlier than usual.  Given that we had arrived to the site pretty late the day before, we wanted more time to address the problems.  We were ready to rock ‘n’ roll, or as Hamdi put it “roll ‘n’ rock”!

    Hamdi testing the EDGES system

    It took us longer than expected to get going from the Boolardy Station this morning because Hamdi was repeatedly examining the EDGES receiver unit while continuously saying “just one more thing”.  It’s important to note how easy it is to lose track of time when you’re thoroughly focused on finding a problem.  There was some bouncing of ideas on the way to site, which ended in Hamdi betting his lunch that the problem was related to temperature.

    Arriving at the DARE site

    We promptly arrived to the site once again, primarily focusing our attention to DARE.  The method of attack was use metal plates (that had a previous life of being cabinet dividers) to pry open the DARE enclosure. Unfortunately, this didn’t work as we had hoped.

    Referencing previous pictures

    Given few options left, we finally went with the contingency plan of cutting the top off the DARE enclosure.  With an image from a prior trip of how the antenna was positioned inside the enclosure, the team carefully made some horizontal incisions across the foam and raised the top portion of the box, opening the system for inspection.  Tragically, a spider was injured during this process – we hope that it is doing well.  Before we altered anything, Hamdi made sure to take a spectrum sample to use for later references – like yesterday, it’s always important to record what happens before you change the system.

    Opening up DARE

    Nostalgically remembering his time working in Goldstone Observatory, Hamdi expressed that he was excited to be tackling this problem despite the pestering flies and steady heat.  With a spectrum established from 1 to 200 MHz, the team expected to find a change in the amplitude of the signals.  We then proceeded to examine the antenna itself.  We also used a total power meter to measure the power connected and disconnected to the antenna.

    Dust Devil

    With less sun but more flies, our second day has produced a bit more results than the first.  The fieldwork here has proven to be substantial but we realize that all the efforts ultimately turn into both fun and challenging experiences.

     
  • josemanuelchavez 9:26 pm on November 23, 2012 Permalink | Reply
    Tags: , , , , , radio   

    Day 1 

    After a +14 hour flight across the Pacific Ocean, another flight across the entire Australian continent, and an 8 hour drive north of Perth to Boolardy Station– it’s been one heck of a ride. After a good night’s rest and a delicious meat-lover’s breakfast, we were on our way to the Murchison Radio Observatory (MRO) site.

    Only a half-hour drive from Boolardy Station, the site is 41 km away from our home base. Along with being the home of the EDGES and DARE projects, it also hosts the Australian Square Kilometer Array Precursor (ASKAP). This array consists of numerous mushroom-looking dish satellites that provide for great scenery while we snaked through the small dirt roads.

    DARE Antenna with ASKAP dishes in the background

     

    Once we arrived to the EDGES/DARE site, we immediately went to inspect the hut that holds the electronics and computers.  The team had arranged this trip to hunt down the reason why EDGES and DARE had been producing some buggy data.

    The weather was reminiscent of the Arizona summer heat.  Cloudless, dry, and with the omnipresent sun shinning down with all of its power.  Without the shrubs, the terrain seemed that of the Martian surface – colonized by the various huts and buildings that the CSIRO had established.

    The first order of business was to set take a spectra of the antenna with our (handy) spectrum analyzer. This is done to establish a baseline of the signal distribution, which is used to compare with later samples.   By using the process of elimination, we go through the wiring as well as the RF chain to see what would cause the larger problem.   Since the issue is intermittent, which is to say that it occurs sporadically, it is quite challenging to find the culprit that is damaging the data quality.

    Discussing the spectrum measurements

     

    In order to prevent the weather from damaging the DARE system, it was housed in a foam box.  We needed to remove the outer part of the box and, while seeming rather easy to do, this proved to be quite a challenging problem so solve.   The team tried to remove the L-brackets without damaging the foam but the foam on the bottom edge seemed like it had melted on the bottom plate and was consequently too strong to remove. A few methods were tried but in the end we were not able to remove the box without damaging the sides. After we tried everything that appeared to be the simplest ways to remove structure, we decided to regroup and attack the problem again tomorrow with some different tools and during a cooler part of the day.

    In an equal but opposite contrast, the food at the station was quite amazing.  Not unlike the cuisine one would find at a fine restaurant – it was something to keep our day on a positive note. Dinner was lamb braised with fresh fava beans over couscous, roasted vegetable salad, and something called “lemon delicious” for dessert.

    Although at many times this day might have appeared as an uphill battle, we learned a lot about what things to do differently.  In science, it’s equally important to know why things don’t work just as much as why they do.

     
  • dannyjacobs 2:01 am on October 26, 2012 Permalink | Reply
    Tags: , , radio   

    The sound of PAPER 

    Today I needed a distraction so I transcoded some PAPER data into sound. It sounds really weird!

     
  • dannyjacobs 6:23 pm on October 24, 2012 Permalink | Reply
    Tags: , dipole antennas, , radio,   

    Creatures of the Night 

    Low frequency radio astronomers do it at night.

    I was re-reading my post from last month and I realized something.  For years, astronomers using radio telescopes have been accustomed to observing, day or night, rain or shine. Of course there are always exceptions, but as a rule, if your desired source was up during the day, this did not present any particular difficulty because the giant dishes could focus away from the sun. Those were the days!

    Now, as we push the boundaries with wider fields of view, like the MWA which looks at almost a third of the sky at a time, we find that we can must limit out observing to times when the sun is set, effectively cutting the telescope time in half!  In fact, as we continue to build sensitivity we might be further restricted to times during the night when the ionosphere has settled down and the “seeing” is good enough.

    Ironically this all happened because we got rid of the steerable dish, that last vestige of similarity to traditional optical telescopes,in favor of dipole antennas that see the entire sky at once.

     
  • jmonkiew 8:34 am on October 23, 2012 Permalink | Reply
    Tags: , , LWA, radio   

    Looking for the First Stars with the Long Wavelength Array 

    Hi, my name is Jackie Monkiewicz. I’m a graduate student working with the Low-frequency Cosmology group. Today I’m going to tell you a little bit about my PhD research with the Long Wavelength Array

    The first station of the Long Wavelength Array. (click to zoom)

    If you drive up to Payson from Phoenix and then turn east on highway 60, you’ll climb up out of the low desert onto the Colorado plateau, through cool pine forests and then into the high desert of New Mexico. Eventually you’ll reach the Plains of San Agustin, a flat empty valley ringed by 10,000-foot mountain ranges. It’s mostly sand and grass and endless sky out here, with really terrible cellphone reception.

    The VLA looming in the background.

    The lack of reception is intentional: scattered around the valley are the giant white dishes of the Very Large Array, of Hollywood and television fame. It’s located so remotely because the radio noise of human civilization can easily drown out the faint signals of astronomical sources. Even passing car engines and cell phones have turned out to be major interference sources at certain frequency ranges observed by the VLA.

    The second half of my PhD research is going to use the VLA, and I’ll talk more about it at a later date.

    But today I’m going to talk about the first part of my PhD research, which centers on small field ringed with barbed wire, a quarter-mile south of the VLA Visitor’s Center. As you walk up, it looks exactly like someone planted several truckloads of oversized TV antennas in the middle of cow pasture. This unsophisticated-seeming array is the first station of the Long Wavelength Array, LWA1, operated out of the University of New Mexico in Albuquerque, and it’s quite a bit more sensitive to longer, meter-sized wavelengths of light(1) than its more-impressive neighbor the VLA. These long wavelengths correspond to frequencies of 30-100 MHz, just below the FM radio band. This frequency, it turns out, is perfect for hunting for the birth of the very first stars.

    Yes, once a upon a time, there were no stars. In fact, for several hundred million years after the Big Bang, the universe was completely dark and devoid of light except for the fading glow of the Cosmic Microwave Background. Astronomers refer to this period of time as the cosmological “Dark Ages.” The Dark Ages ended when the first stars began to form around 400 million years after the Big Bang, at redshifts of 20 or 40 (2).

    Artist’s schematic of the cosmological Dark Ages and the epoch of hydrogen reionization.

    Astrophysical models of the formation of these stars suggest they were very large and very massive, much brighter and hotter than our own sun. These first few stars filled the dark universe with ultraviolet radiation first. At the time, most of the universe was filled with cooling hydrogen gas. The radiation from these stars will have heated the hydrogen, and then eventually ionized it, creating a universe of hot plasma bubbles threaded through with filaments of cooler, denser gas.

    Even though we can’t currently see the stars themselves with our current telescopes, radio astronomers think we should be able to detect their impact on the hydrogen gas. What objects first lit up the universe, and when, is one of the key “big questions” identified by the 2010 Astronomy and Astrophysics Decadal Survey:

    http://reionization.org

    And that’s what I’m doing with a pasture full of bow-tie antennas in the middle of nowhere, New Mexico: looking for the first stars to form in the Universe. Next time I’ll tell you how I’m going to do that.

    1. Radio signals are actually just another kind of light. We can describe light by either its frequency or the size of its wavelength: radio light has wavelengths millions or billions time larger than the light your eyes see. So instead we use antennas to detect it. Typically the size of the antenna tells you about how physically large the wavelength of the incoming signal is.

    2. Redshift increases as we look back in time. So smaller redshifts correspond to the modern Universe, while larger redshifts mean that we are looking back to early times, closer and closer to the Big Bang.

     
  • josemanuelchavez 1:10 am on August 28, 2012 Permalink | Reply
    Tags: , , , radio   

    What does one super car battery say to the other five? 

    Don’t get short with me.

    One of the many goals of radio astronomy is collecting data from remote signals while ignoring terrestrial traces. The best way to do this is to position the instruments in isolated areas, but doing so brings up another problem.  Some of the environments that are best suited to collect data are also out of the reach of traditional electric grids and thus, dependable power.  Our solution to this problem are four photovoltaic panels that provide reliable and renewable energy. This has to be constructed alongside a system that will monitor its important characteristics (array power, battery voltage, temperature, etc.) remotely.

    Image

    My project was to create this system as part of an ongoing experiment in Western Australia and possibly for a new deployment on a remote Pacific island.  While four PV panels might feel like a comfortable bet for a small array of instruments – there still needs to be a place where all the power is stored. This duty is performed by six ‘super car batteries’. They weren’t removed from a caped, crime-fighting car but are dubbed ‘super’ simply because of their high electric charge capacity. You see, a typical car battery holds around 60 Ah (ampere-hours).  These guys get 110 Ah.  Unfortunately, they probably didn’t come from Krypton.

    Image

    Connecting these components requires both caution and patience.  Each lead-acid battery is just over 60 lbs – bringing the total to more than 375 lbs! Obviously, dropping or heat exposure is not advised. For housing, we a use a weatherproof dock box. A big concern when hooking up so many batteries is an electric short. But, you can’t really electrocute yourself with something at this low voltage (12V). Touching the terminals with your bare hands will result in no harm.  Instead, dropping something like a chrome plated wrench on the polar ends will cook up a big spark and will cause the batteries to heat up quickly.

    Image

    No need for worry! We’ve established several redundancies to prevent any of these hazards.  Among other things, the terminals and wires are completely covered and restrained from wiggling around.  As a matter of fact, the system – the Remote Solar Power and Monitoring System – is just about done.  All major components and wires are already secured and labeled.  In a week’s time, it should be tanning on the roof enjoying the nice Arizona sun.  Up, up, and away!

     
  • dannyjacobs 9:56 pm on August 20, 2012 Permalink | Reply
    Tags: , , radio   

    Here be dragons 

    Greetings readers.  My name is Danny Jacobs. I’m a postdoc working for Judd Bowman here in the SESE Low Frequency Cosmology (LoCo) lab. My job is to help commission the Murchison Widefield Array (MWA) in Australia and the Precision Array for Probing the Epoch of Reionization (PAPER) in South Africa.  I visit the telescopes to help with construction and the rest of the time I try to make sense of the data. Someday I want to make an image of the ultra-distant hydrogen between the first galaxies. This is my first post here on ASU Explorers.

    A handy guide to the radio sky hanging in my office. Dragons locations drawn in red.

    Last month I was imaging the sky with PAPER and I made an amazing discovery… or so I thought.  Within a few months a dim, unremarkable supernova remnant had become brighter than the Crab Nebula, one of the brightest radio sources in the sky.  I had discovered the Sun! Again!

    The radio sky is a big invisible place and its easy to lose track of whats going on. Disgusted with myself, I took a break from imaging and put together a map of the sky. There it is to the right, hanging on my office wall. (pdf) It has the brightest few sources, the galaxy, and the seasonal position of the Sun. I also made a supplemental map showing the footprint of my telescopes on the sky. (pdf) The footprints are so large, its easy to forget what will be visible.

     
  • seasterb 10:07 am on March 24, 2012 Permalink | Reply
    Tags: , , , radio   

    Wrapping Up the Week 

    Today was our last day on site here at the MRO in Western Australia! We started the morning again bright and early at 5:30am with a delicious breakfast. Then we had a short telephone conference (yay modern technology!) with Dr. Rich Bradley (NRAO/UVA) who built the antenna. We were inquiring about the response of the system to low frequency signals the antenna was picking up. Once we had an idea of what we needed to look at when we got to the site, we headed out.

    Cleaning up.

    We started at the site by tidying our little hut up. A lot of the electronics and tools that we brought with us were meant to stay here in Australia, but we had to go through everything to figure out what was staying and what was being packed. After going through everything and making a nice inventory of what was remaining here in Australia, we put everything in organized boxes and either stored them in the hut or put them in the car.

    Checking the system.

    Once everything was organized, we began our final system tests that we had planned on doing after our telephone conference this morning. We did our tests with the spectrum analyzer and determined that in order to the get the best data, we need to add a high pass filter that should get rid of a bit of the lower frequencies that are complicating the observations.

    Judd checking our handy work.

    During lunch, Judd and Hamdi discussed the possible ways of making a filter here in Australia, but for quality and reliability, we decided we will ship the filter once we get home and have a staff member here at the MRO who is familiar with our system install it. After this installation the DARE data will be fully functional and up for analysis!

    The computer.

    We are now back at the homestead doing laundry, packing our belongings, and relaxing after a hard week of work. Judd is also preparing preliminary reports and data plots from all our efforts here in Australia. We will be up again tomorrow at the crack of dawn to start our long journey back to the US with our 8 hour drive back to Perth!

    Goodbye MRO.

    We would also like to extend our thanks to all the people and staff here at the MRO and Boolardy Station. They were so hospitable and sociable; it made our stay here all the much more enjoyable. I would like to especially thank Barry, Michael, Shaun, Lou, and John specifically. They all helped us whenever we needed anything! Thanks!
    Sarah

     
  • seasterb 9:52 am on March 23, 2012 Permalink | Reply
    Tags: , , , radio   

    Antenna Set Up 

    Well the last three days have been the most busy, tiring, and exciting of the whole trip here in Western Australia. Once the antenna arrived late Wednesday afternoon, we had a lot to do to get the whole system up and running.
    On Thursday morning, we woke up before the sunrise to get breakfast and were on our way to the site just after 6am. When we arrived, the huge crate that held the antenna and all the other parts to put it together was sitting at the CSIRO site office. Hamdi was quite antsy to get the box to the hut and crack it open. The very kind and efficient staff here at MRO used a crane to drive it the mile from the entrance to the hut for us. Once it was there, we read the directions on how to get the crate open.

    The Crane

    Opening the crate.

    The antenna and the beautiful weather.

    After fiddling for about an hour with all the screws that needed to be removed to get the weather shield with the antenna out of the case, we were finally able to pull it out of the crate and set it safely on the ground. As you can see in the pictures, there are four very large ground screens that we had to unload and carry about 150 feet to the place where the antenna is going to sit while it gathers data. We ran into the issue of how to get it all bolted together when you had to bolt from the underside but there were no legs to have space to get underneath it. We decided that the best way to do it was to bolt it all together upside down and then flip it over.

    One panel of the ground screen.

    Judd and Hamdi putting the ground screen together.

    By the time we had it all bolted together it was time to leave the site because it was getting dark. People are not allowed to work past sunset because of all the wild animals that are on the roads when driving in the dark. So, we headed back to the homestead and had dinner.

    Sunset

    Last night was a beautiful night to look at all the stars because there were no clouds to be seen. Even though we were completely exhausted from the long day of work, we set out down the drive way of the homestead to get a better view of all the stars. It was absolutely spectacular to see so many stars! We were even able to see the Magellanic Clouds. According to NASA, “The Magellanic Clouds are irregular dwarf galaxies orbiting our Milky Way galaxy”. To read more about these galaxies, go to http://heasarc.nasa.gov/docs/cosmic/nearest_galaxy_info.html.

    Magellanic Clouds

    Milky Way

    This morning we also woke up before sunrise and were out the site just after 6am, and more excited than yesterday (If you know Hamdi, that excitement was very hard to beat) because of the anticipation of seeing first light with our antenna here in Australia. We started by flipping the ground screen and feeding the power and signal cables though the hole in the center. Once this was done, we put the base of the Styrofoam stand on the ground screen.

    The ground screen and antenna base.

    Back in the hut, before we could progress further on the set up of the antenna, we plugged all the power supplies in and tested them with each of the electronic components to make sure the right voltages and currents were being drawn. Once this was verified, we set out into the wind to complete the setting up process. The balun, which transfers the signal from the antenna to the receiver though a coaxial cable (just like a TV cable), was carefully hooked into the antenna and, with a lot of balance and patience, the antenna was finally safely standing here in the Outback.

    The complete antenna!

    We headed back to the hut to power everything up and check to make sure the antenna was working. To all of our great joy, first light was achieved! Now all that is left to do is make sure that we can control the whole system remotely with no kinks or disasters. Once this is complete, we will have done everything that we came here to do 100 percent successfully!

    Looking at the antenna spectra.

    Sarah

    These are the quotes from the last few days!
    We have a car that has a remote start which is very finicky. Judd said that getting the car to start was like alchemy, to which Hamdi replied: “Even alchemy is more predictable than this car!”

    Hamdi is a cultural sponge and has a love for the English language. So whenever he finds a word that we say is interesting, he always repeats it for the next 30 minutes, forgets it, asks for us to say it again, and the cycle beings again. Cassie commented, “Hamdi is like having a parrot along.”

     
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