A browser tool by developer Efe turns any computer monitor into a VHF transmitter with no hardware modifications. The mechanism is pixel clock manipulation: multiply horizontal resolution, vertical resolution, and refresh rate using CEA-861 timing standards, and you get your emission frequency. A 1080p display at 60 Hz produces 2200 x 1125 x 60, which lands at exactly 148.500 MHz.
The tool, available at waiixd.github.io/vhf-morse-transmitter-monitor, encodes Morse code by flickering black and white pixel patterns to maximize voltage-state transitions on HDMI or DisplayPort lines. The signal leaks from the cable, connector, and monitor itself. Reception requires holding a radio antenna directly against the display. The original article is worth reading for the precise breakdown of how blanking intervals affect the frequency calculation.
Intentional transmission on unlicensed bands is illegal regardless of signal strength. That legal caveat aside, this project demonstrates a concrete, reproducible path from display timing math to RF emission. The same principle underlies decades of TEMPEST research and side-channel attacks on video hardware.
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