Fifty Things You Can Do with a Software Defined Radio (SDR) This project chronicles a week-long adventure exploring the electromagnetic spectrum using an affordable USB SDR dongle and antennas. The author demonstrates 50 fascinating applications of SDR technology, learning about radio communications, satellite signals, and various wireless transmissions along the way. --- What Is an SDR? A Software Defined Radio (SDR) uses a computer for most processing instead of analog components. It can detect a wider range of frequencies than typical consumer radios. Popular budget hardware example: RTL-SDR Blog V4 dongle (~$30), with antenna kits available. Hardware & Software Used Hardware: RTL-SDR Blog V4 USB dongle, antenna kits (dipole, telescopic, wire antennas). Software: SDR++, SDRangel, rtl433, fldigi, WSJT-X, Sonic Visualiser, and GNU Radio. Internet SDR receivers can be accessed online for free. Antenna Tips Dipole antenna length approximates half the wavelength: length (each side) ~ 72 / frequency (MHz). Orientation typically vertical. Special setups used for satellites and aircraft tracking. --- Selected Highlights from the 50 Things Day 1: Basics & Broadcast Signals Listen to FM Radio (87.5-108 MHz, FM) — Explore local stations easily. Listen to Freenet (149.01-149.11 MHz, FM) — Germany-specific public frequency band used by locals. Receive Weather Conditions from Airports (AM) — Automatic Terminal Information Service (ATIS) reports. Track Aircraft via ADS-B (1090 MHz) — Build antennas to decode live aircraft positions. Listen to Stereo FM Details — Understand pilot tones and stereo encoding. Receive Road Traffic Information via Radio Data System metadata embedded in FM broadcasts. Listen to Amateur Radio Conversations (144-146 MHz, FM) — Hear licensed operators talk. Listen to Digital Audio Broadcast (174-240 MHz) — Digital radio with no noise. Listen to PMR446 (446 MHz, FM) — Short-range private mobile radio signals. Day 2: Sensors & Transport Tracking Read Neighbors’ Sensors (433 MHz) — Decode temperature, humidity, and air pressure sensors. Track Ships via AIS (162 MHz) — Monitor maritime vessel locations. Detect GSM Phone Activity (876-959 MHz) — See phone call signals and voice volume patterns. Day 3: Satellites & Signals Receive Satellite Signals (136-138 MHz) — NOAA weather satellite signals (images attempted). Admire TETRA Signals — Encrypted police communications visualized. Ponder Mysterious Signals — Unknown digital signals and broadband transmissions. 18-19. Track & Hunt Weather Balloons (400-406 MHz) — Decode radiosonde data and attempt physical retrieval. Receive Amateur Packet Radio (144.8 MHz) — Digital packets with position and weather info. Day 4: Building Antennas & Morse Code Receive Morse Code (10.10-10.13 MHz, CW) — Hear international amateur Morse transmissions. Maritime Weather Reports (11.039 MHz, RTTY) — Decode German weather service broadcasts. Receive Digital Modes like FT8 (10.130-10.15 MHz) — Popular global ham radio digital mode. Detect Notebook Charger Noise — Unplugging charger removes interference. 25-26. Ionosondes and Radar Signals (6-30 MHz) — Scientific and ocean radar pulses discovered. Listen to SSB Conversations (<30 MHz) — Single sideband voice communications. Listen to AM Radio from Around the World — Shortwave broadcasts reflected by the ionosphere. Day 5: Further Exploration & Time Signals Listen to CB Radio (26.965-27.405 MHz) — Citizen band used internationally by truckers. Assess Radio Wave Propagation with Beacons (14-28 MHz, CW) — International Beacon Project stations broadcast callsigns to measure conditions. Receive Time Signals (9996 kHz, CW) — Russian RWM time station. Receive Weather Fax