Listening to Ham Radio Operators Using the International Space Station

Amateur radio (ham radio) is a hobby many different type of people enjoy. From your next door neighbor to doctors to truck drivers, the operators come from all walks of life. One thing they all have in common is a general interest in wireless communication and electronics. Ham radio is almost always used for fun and general interest, however it has also served as a critical outlet for communication in times of disaster. When regular communication channels fail such as cell phone networks or the internet, communication can still happen through amateur radio service. In fact, this was the case during events such as the 2013 Colorado floods, Hurricane Katrina, and the 9/11 tragedy.

Recently, Gabe Emerson from the Saveitforparts YouTube channel has given a brief run down on how anyone can easily begin listening to ham radio frequencies. Specifically, he demonstrates how to listen to the amateur radio repeater aboard the international space station (ISS). The repeater can be used to make contact between two locations over a long range by essentially bouncing a signal off the space station.

For his simple method of listening to the repeater aboard the ISS, Emerson uses a cheap two way handheld radio which can be purchased off Amazon in the price range of $20 to $60. He then shows that the frequency of communication as well as status of the ISS ham radio repeater can be found on the website ariss.org. Next, an additional website is used that tracks the location of the ISS. It shows the current location of the ISS as well as when and where it will be passing by your nearest location. Using this information he shows he can tune his radio to the frequency of 437.8MHz and receives various calls from ham operators while the ISS is passing overhead.

Emerson also goes on to explain how to get better reception when trying to receive signals. One suggestion is trying to receive at different frequencies while the ISS passes overhead. The reason for this is a phenomenon known as the doppler effect. Basically, the frequency appears higher when the ISS is moving towards you and lower while it is moving away. The shift in frequency will only be several KHz, in this case +/-10KHz, however it can make the difference between receiving clean audio and receiving audio full of noise. An additional method to achieve better reception includes using a better antenna. For the small handheld radio he uses in his demonstration he recommends a Nagoya NA-771 which is larger, cheap, and more optimal for reception in the ham bands being used.

For the more complicated method of receiving ham signals from the ISS repeater, the plans for an automated tracking system are unveiled. This includes using a directional Yagi antenna tuned to 437.8MHz mounted on an old security camera PTZ mount. This will result in the highest magnitude signal possible from the satellite. The implementation of automatic antenna control and computer controlled aiming is part of future plans for the project. The hope is to be able to use the system to not only pick up the ISS repeater signals, but also signals from additional satellites such as cubesats or satellites that are further away that are harder to receive.