PSK31 Modulation Polyglots: Weird Machines in Digital Radio
Travis Goodspeed and Sergey Bratus demonstrate radio modulation polyglots, embedding multiple valid audio and data interpretations within a single PSK31 transmission.
Summary
The Theory of Modulation Polyglots and Weird Machines
Polyglot data files exist simultaneously as valid inputs across multiple parsers; in RF communications, modulation polyglots decode into distinct messages across different demodulators.
Deconstructing PSK31 Phase Modulation
Travis Goodspeed and Sergey Bratus analyze PSK31 varicode character encoding, baud rates, and carrier phase shifts over high-frequency (HF) bands.
Crafting Polyglot Audio and Digital Radio Frames
The speakers demonstrate synthesizing audio waveforms that sound like speech to human listeners while cleanly decoding as structured ASCII text in digital radio software.
Implications for Spectrum Monitoring and Deep Packet Inspection
The authors discuss how modulation ambiguity challenges automated wireless surveillance, censorship filters, and signals intelligence collection.
Related talks
Ham Radio Village·56 min
Jon Marler
Jon Marler breaks down modern amateur radio digital modes (FT8, JS8Call, APRS), demonstrating keyboard-to-keyboard data transmission over high frequencies.
Village Interviews·1 min
A rapid spotlight on the Maritime Hacking Village exploring shipboard control networks, satellite navigation, and vessel cybersecurity at DEF CON 34.
Car Hacking Village·24 min
Vlad Gostomelsky
GPS spoofing attacks against vehicle navigation and autonomous systems.