How to Contact the ISS with a $30 Radio

In this presentation at the DEF CON 29 Ham Radio Village, Gregg Horton (K6XSS) presents an accessible, beginner-friendly guide to establishing amateur radio contact with the International Space Station (ISS) using an inexpensive handheld transceiver. He opens at 03:00 by dispelling the belief that amateur radio requires costly equipment, explaining that high-frequency satellite communication can be accomplished with a basic thirty-dollar handheld radio like the Baofeng UV-5R.

Gregg explains the operation of the amateur radio cross-band repeater aboard the ISS at 06:00, detailing how low-Earth orbit satellites receive VHF signals and retransmit them across vast geographic footprints. At 09:00, he showcases decoding Slow Scan Television (SSTV) image transmissions broadcast by Russian cosmonauts during special commemoration events using free audio demodulation apps on smartphones.

Walking through orbital dynamics at 12:00, Gregg demonstrates how to use mobile satellite tracking tools to identify pass windows and antenna elevation angles during the typical nine-minute transit window. He details programming standard VHF uplink (145.990 MHz) and UHF downlink (437.800 MHz) frequencies with required CTCSS tones at 15:00, and explains compensating for orbital Doppler shift at 18:00. He concludes at 21:00 by encouraging amateur radio operators to expand their experimentation to amateur cubesats and orbital repeaters. (AI summary — Gemini Flash)