Show HN: ClassD-VHF-Transmitter – Covert RF Transmission via Phone Speaker PWM

Category: security

Tags: rf, tempest, android, side-channel, security-research

Score: 5.8/10 (Innovation: 7, Technical: 6, Documentation: 6, Utility: 4)

An Android proof-of-concept that exploits Class-D audio amplifiers to emit VHF RF via inaudible ultrasonic PWM tones, enabling covert Morse code transmission. It demonstrates a novel TEMPEST-style side channel using standard smartphone hardware without special permissions, appealing to RF security researchers.

Target audience: security researchers, RF hobbyists, hardware hackers

Repository: https://github.com/TA1EEI/ClassD-VHF-Transmitter · Kotlin · MIT · 7 stars

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