MAKE’s awesome interns tell about the projects they’re building in the Make: Labs, the trouble they’ve gotten into, and what they’ll make next.
By Tyler Moskowite, engineering intern
One of my all-time favorite projects to build has to be the Yagi Antenna from Make: Volume 24. The Yagi Antenna tunes into satellites orbiting the Earth and listens to their transmissions. I am still fascinated with the simplicity of the project. Besides the UHF FM radio, the materials required for the build are easy to find and inexpensive. In under two hours you will be able to tune in to the signals from space. Anyone who has the slightest interest in space, radio, or even spying should consider building this project. The most time-consuming part of this project is waiting for satellites to appear.
In my opinion the most important part of this entire project is patience. There are only a few operational satellites that radio operators use on a daily basis, and even then transmissions can be scarce or short. I had the most success with the following satellites: AO-ECHO, SAUDISAT 1C, and the HO-68. Make sure you get the latest information available on these satellites by going to their official web page.
For this build I was using the Uniden BC72XLT hand-held scanner, as seen in the materials list from the magazine. I initially had issues listening in on the satellite transmissions due to the Doppler effect. The Doppler effect changed the frequency of the signal just enough to distort the incoming message so that all I heard was static noise. Luckily the Uniden BC72XLT has a wonderful feature which allows you to set it to scan a range of frequencies. This feature compensates for the minimal frequency distortion, so there is less static when listening to the message. Although it may require a bit of tinkering around with the instruction manual to get this to work for you, it’s worth the effort and time.
Finding the exact location of satellites and how they rise and fall in the sky can be a bit tricky. The article recommends you start with Heavens-Above site for finding satellite orbital paths, but I have found that the times provided by this website might not always be right. Make sure you know the direction that the satellites orbits when you are aiming your antenna. The first time I tried to listen in on a satellite I had been starting at the wrong side of the horizon, which is why the transmissions were so short. You can reference the direction via Heavens-Above, and move the antenna to track the movement of the satellite and pick up more of the transmitted signal.
Be sure to note the angle that the satellites rise to, and the time that it is expected to pass your location. You will be able to pick up a better signal if the satellites are traveling at higher relative altitudes; however, the majority of the satellites orbit at lower angles and produce mediocre results. At most there are only five high-angle passing satellites per day, so timing will be important. Take some of my failures into account, and go out and have some success in your first amateur satellite listening adventure.
Check out MAKE Volume 24:
MAKE blasts into orbit and beyond with our DIY SPACE issue. Put your own satellite in orbit, launch a stratosphere balloon probe, and analyze galaxies for $20 with an easy spectrograph! We talk to the rocket mavericks reinventing the space industry, and renegade NASA hackers making smartphone robots and Lego satellites. This, plus a full payload of other cool DIY projects, from a helium-balloon camera that’s better than Google Earth, to an electromagnetic levitator that shoots aluminum rings, and much more. MAKE Volume 24, on sale now.