MIT is well known for rigorous courses, but they also have a special four-week term at the start of each year called the IAP — Independent Activities Period. This year, the MIT Radio Society had several interesting presentations on both the history and application of radio. You weren’t there? No problem, as the nine lecture were all recorded for you to watch at your leisure. You can see one of the nine, below.
These aren’t some five minute quicky videos, either. They are basically live captures that run anywhere from an hour to almost two hours in length. The topics are a great mix including radio history, software-defined radio, propagation, radio astronomy, RADAR, and even 5G.
You might have to pick and choose. Some of the lectures are suitable for just about anyone. Some assume a bit more radio expertise in electronics or math. Still, they are all worth at least a cursory skim to see if you want to really sit and watch in detail. The only nitpick is that some presenters used a laser pointer that doesn’t show up on the inset slide graphics in the video. That makes sense because the inset slides are not really in the room, but it can make it a little difficult to understand what the speaker is pointing to on a crowded slide.
Of course, if you want to dive deep and you need more background, MIT — along with many other institutions — will let you use their learning material for free. We were especially fans of the circuits class but there are many others including just raw materials from OCW.
We are used to imagining radio telescopes as immense pieces of scientific apparatus, such as the Arecibo Observatory in Puerto Rico, or the Lovell telescope in the UK. It’s a surprise then that they can be constructed on a far more modest sale using off-the-shelf components, and it’s a path that [Gonçalo Nespral] has taken with his tiny radio telescope using a satellite dish. It’s on an azimuth-elevation mount using an Ikea lazy susan and a lead screw, and it has a satellite TV LNB at the hot end with a satellite finder as its detector.
So far he’s managed only to image the wall of his apartment, but that clearly shows the presence of the metal supporting structure within it. Taking it outdoors has however not been such a success. If we wanted to hazard a guess as to why this is the case, we’d wish to look at the bandwidth of that satellite finder. It’s designed to spot a signal from a TV broadcast bird over the whole band, and thus will have a bandwidth in the hundreds of MHz and a sensitivity that could at best be described as a bit deaf. We hope he’ll try a different path such as an RTL-SDR in the future, and we look forward to his results.
Scientists don’t know exactly what fast radio bursts (FRBs) are. What they do know is that they come from a long way away. In fact, one that occurs regularly comes from a galaxy 3 billion light years away. They could form from neutron stars or they could be extraterrestrials phoning home. The other thing is — thanks to machine learning — we now know about a lot more of them. You can see a video from Berkeley, below. and find more technical information, raw data, and [Danielle Futselaar’s] killer project graphic seen above from at their site.
The first FRB came to the attention of [Duncan Lorimer] and [David Narkevic] in 2007 while sifting through data from 2001. These broadband bursts are hard to identify since they last a matter of milliseconds. Researchers at Berkeley trained software using previously known FRBs. They then gave the software 5 hours of recordings of activity from one part of the sky and found 72 previously unknown FRBs.
Radio waves are received on antennas, for which when the signal in question comes over a long distance a big reflector is needed. When the reception distance is literally astronomical, the reflector has to be pretty darn big. [The Thought Emporium] wants to pick up signals from distant satellites, the moon, and hopefully a pulsar. On the scale of home-built amateur radio, this will be a monstrous antenna. The video also follows the break.
In hacker fashion, the project is built on a budget, so all the parts are direct from a hardware store, and the tools are already in your toolbox or hackerspace. Electrical conduit, chicken wire, PVC pipes, wood blocks, and screws make up most of the structure so put away your crazy links to Chinese distributors unless you need an SDR. The form of the antenna is the crucial thing, and the shape is three perpendicular panels as seen in the image and video. The construction in the video is just a suggestion, but it doesn’t involve welding, so that opens it to even more amateurs.
Even if you are not trying to receive a pulsar’s signature, we have hacks galore for radios and antennas.
What must it be like to devote your life to answering a single simple but monumental question: Are we alone? Astronomer Jill Tarter would know better than most what it’s like, and knows that the answer will remain firmly stuck on “Yes” until she and others in the Search for Extraterrestrial Intelligence project (SETI) prove it otherwise. But the path she chose to get there was an unconventional as it was difficult, and holds lessons in the power of keeping you head down and plowing ahead, no matter what.
To get to the point where she could begin to answer the fundamental question of the uniqueness of life, Jill had to pass a gauntlet of obstacles that by now are familiar features of the biography of many women in science and engineering. Born in 1944, Jill Cornell grew up in that postwar period of hope and optimism in the USA where anything seemed possible as long as one stayed within established boundaries. Girls were expected to do girl things, and boys did boy things. Thus, Jill, an only child whose father did traditional boy things like hunting and fixing things with her, found it completely natural to sign up for shop class when she reached high school age. She was surprised and disappointed to be turned down and told to enroll in “Home Economics” class like the other girls.
She eventually made it to shop class, but faced similar obstacles when she wanted to take physics and calculus classes. Her guidance counselor couldn’t figure why a girl would need to take such classes, but Jill persisted and excelled enough to get accepted to Cornell, the university founded by her distant relation, Ezra Cornell. Jill applied for a scholarship available to Cornell family members; she was turned down because it was intended for male relatives only.
Undeterred, Jill applied for and won a scholarship from Procter & Gamble for engineering, and entered the engineering program as the only woman in a class of 300. Jill used her unique position to her advantage; knowing that she couldn’t blend into the crowd like her male colleagues, she made sure her professors always knew who she was. Even still, Jill faced problems. Cornell was very protective of their students in those days, or at least the women; they were locked in their dorms at 10:00 each night. This stifled her ability to work on projects with the male students and caused teamwork problems later in her career.
No Skill is Obsolete
Despite these obstacles, Jill, by then married to physics student Bruce Tarter, finished her degree. But engineering had begun to bore her, so she changed fields to astrophysics for her post-graduate work and moved across the country to Berkeley. The early 70s were hugely inspirational times for anyone with an eye to the heavens, with the successes of the US space program and leaps in the technology available for studies the universe. In this environment, Jill figured she’d be a natural for the astronaut corps, but was denied due to her recent divorce.
Disappointed, Jill was about to start a research job at NASA when X-ray astronomer Stu Boyer asked her to join a ragtag team assembled to search for signs of intelligent life in the universe. Lacking a budget, Boyer had scrounged an obsolete PDP-8 from Berkeley and knew that Jill was the only person who still knew how to program the machine. Jill’s natural tendency to fix and build things began to pay dividends, and she would work on nothing but SETI for the rest of her career.
From the Bureaucratic Ashes
SETI efforts have been generally poorly funded over the years. Early projects were looked at derisively by some scientists as science fiction nonsense, and bureaucrats holding the purse strings rarely passed up an opportunity to score points with constituents by ridiculing efforts to talk to “little green men.” Jill was in the thick of the battles for funding, and SETI managed to survive. In 1984, Jill was one of the founding members of the SETI Institute, a private corporation created to continue SETI research for NASA as economically as possible.
The SETI Institute kept searching the skies for the next decade, developing bigger and better technology to analyze data from thousands of frequencies at a time from radio telescopes around the world. But in 1993, the bureaucrats finally landed the fatal blow and removed SETI funding from NASA’s budget, saving taxpayers a paltry $10 million. Jill and the other scientists kept going, and within a year, the SETI Institute had raised millions in private funds, mostly from Silicon Valley entrepreneurs, to continue their work.
The Institute’s Project Phoenix, of which Jill was Director until 1999, kept searching for signs of life out there until 2004, with no results. They proposed an ambitious project to improve the odds — an array of 350 radio telescopes dedicated to SETI work. Dubbed the Allen Telescope Array after its primary patron, Microsoft co-founder Paul Allen, the array has sadly never been completed. But the first 42 of the 6-meter dishes have been built, and the ATA continues to run SETI experiments every day.
Jill Tarter retired as Director of SETI Research for the Institute in 2012, but remains active in the SETI field. Her primary focus now is fundraising, leveraging not only her years of contacts in the SETI community but also some of the star power she earned when it became known that she was the inspiration for the Ellie Arroway character in Carl Sagan’s novel Contact, played by Jodie Foster in the subsequent Hollywood film.
Without a reasonable SETI program, the answer to “Are we alone?” will probably never be known. But if it is answered, it’ll be thanks in no small part to Jill Tarter and her stubborn refusal to stay within the bounds that were set for her.
[Scott Tilley] was searching for radio signals from the Air Force’s top-secret ZUMA satellite. He found something that is — we think — much more interesting. He found NASA’s lost satellite called IMAGE. You are probably wondering why it is interesting that someone listening for one satellite found another one. You see, NASA declared IMAGE dead in 2005. It went silent unexpectedly and did not complete its mission to image the magnetosphere.
NASA did a failure review and concluded that in all likelihood a single event upset caused a power controller to trip. A single event upset, or SEU, is a radiation event and should have been automatically recovered. However, there was a design flaw that failed to report certain types of power controller failures, including this one.
The report mentioned that it might be possible to reset the controller at a specific time in 2007, but given that NASA thought the satellite was out of commission that either never occurred or didn’t work. However, something apparently woke the satellite up from its sleep.
[Scott] did a lot of number crunching to determine that the satellite’s spin rate had only decreased a little from its operational value and that the doppler data matched what he expected. [Scott] can’t read or command the telemetry, so he doesn’t know how healthy the satellite is, but it is at least operational to some degree. It’s really neat to see members of the team that worked on IMAGE leaving comments congratulating [Scott] on the find. They are working to get him data formatting information to see if more sense can be made of the incoming transmissions.
Who knew listening to satellites could be so exciting? If you want to build your own ground station, you might be interested in this antenna mount. If you need to know what’s overhead, this can help.
Have you got a spare Dish Network antenna lying about? They’re not too hard to come by, either curbside on bulk waste day or perhaps even on Freecycle. If you can lay hands on one, you might want to try this fun radio telescope build.
Now, don’t expect much from [Justin]’s minimalist build. After all, you’ll be starting with a rather small dish and an LNB for the Ku band, so you won’t be doing serious radio astronomy. In fact, the BOM doesn’t include a fancy receiver – just a hacked satellite finder. The idea is to just get a reading of the relative “brightness” of a radio source without trying to demodulate the signal. To that end, the signal driving the piezo buzzer in the sat finder is fed into an Arduino through a preamp. The Arduino also controls stepper motors for the dish’s azimuth and elevation control, which lets it sweep the sky and build up a map of signal intensity. The result is a clear band of bright spots representing the geosynchronous satellites visible from [Justin]’s location in Brazil.