Things you can do with a Software Defined Radio (2024)

Original Article ↗ Hacker News Discussion ↗

Overall reaction to the article

  • Many found the “50 things” format inspiring and fun, motivating them to buy or dust off SDRs and try projects, including with kids.
  • The “Make 50 Things of Something” approach itself was praised as a creativity and learning technique.

Performance and access issues

  • Numerous readers reported the article loading extremely slowly due to large, non-lazy-loaded images and HN traffic (“hug of death”).
  • Several shared archive.today and Wayback Machine mirrors to make it readable.

Satellites and changing RF landscape

  • Discussion that older NOAA APT weather satellites have been decommissioned; simple setups for those images are no longer possible.
  • Newer weather satellites (e.g., GOES) require more capable antennas and kits; some linked off-the-shelf hardware.
  • Debate on what happens to “dead” satellites: most are passivated and left to decay over ~150 years, sometimes with pyrofuses to prevent accidental reactivation.

SDR hardware, software, and capabilities

  • Wide range of devices discussed: RTL-SDR (cheap RX), HackRF, USRP B210, PlutoSDR, AD936x clones, up/down-converters.
  • Clarification that modulation is mostly a software concern; hardware limits are frequency range, bandwidth, ADC resolution, and interface (USB2 often “good enough” for many GHz-band tasks).
  • GNU Radio is seen as powerful and widely used in RF industry, but complex; suitable for prototyping, less ideal for some production full-duplex systems due to threading and latency issues.
  • Alternatives like SDR++, rtl_433, rtl_amr, and various niche tools were mentioned.

Real-world projects and anecdotes

  • Examples: ADS-B feeds, 433 MHz sensor decoding into MQTT/Home Assistant, TPMS and utility meters, DIY GSM/4G/5G base stations, water-leak detection via AMR meters.
  • Personal stories about walkie-talkies and radios leading to lifelong friendships and memorable social encounters.

Direction finding and triangulation

  • Interest in KrakenSDR and phase-based direction finding; TDoA discussed as simpler but with limited spatial resolution.
  • Some are experimenting with perimeter receivers to map local RF sources (including tracking pets).

Legal, privacy, and ethics

  • German law on “messages not meant for the general public” debated, especially for aviation/maritime comms; interpretation remains unclear.
  • In the US, listening to pagers is said to be illegal; several recount receiving highly sensitive medical pager data, calling it both fascinating and disturbing.
  • Discussion of citizen.com as an example of scanner-based products, with mixed views on fear-based UX and privacy vs. public-interest use cases.

Advanced and unconventional uses

  • Additional SDR ideas beyond the article: Meteor satellites, DRM on shortwave, analog TV, GPS/Galileo/BeiDou, TEMPEST/Van Eck attacks on screens and HDMI, passive radar, instrument landing system monitoring, IR remote decoding, and listening to Brazilian pirates on aging US military satellites.

Getting started & RF practicalities

  • For beginners, the rtl-sdr.com dongle is repeatedly recommended.
  • Notes that cheap bundled coax is very lossy at HF; in noisy urban environments, random-wire antennas perform poorly, and active E-field whips or magnetic loops are suggested as better options.
  • Several shared learning resources: Practical SDR (book), online tutorials (e.g., pysdr.org, GNURadio-based courses).