Somewhere between the video signal and the open air, a developer named Efe found a frequency hiding inside the ordinary monitor. By treating the pixel clock not as a display mechanism but as a radio oscillator, he coaxed a standard 1080p screen into transmitting Morse code at 148.500 MHz — no radio hardware required. It is a reminder that the devices we take for granted are built on physical principles that do not care about their intended purpose, and that curiosity about timing diagrams can reveal unexpected dimensions in familiar tools.
Browser Tool Turns Your Monitor Into a VHF Radio Transmitter
Your monitor, built to contain signals, becomes a transmitter
Mark
So the monitor is actually transmitting radio waves? How is that even possible?
Mimi
The display needs a pixel clock—a timing signal that synchronizes everything. That clock frequency, when you do the math right, lands in the VHF band. The HDMI cable carries the video signal, and if you make the pixels flicker in just the right way, you create voltage transitions that radiate.
Luke
But how strong is the signal? The article says you need the antenna right against the screen.
Mimi
Very weak. Monitors are shielded specifically to prevent this kind of leakage. You're fighting against the design of the equipment.
Mark
Is this actually useful for anything, or is it just a proof of concept?
Mimi
It's proof of concept. Efe made it transmit Morse code, which is clever, but you're not going to have a real conversation this way. The range is essentially zero.
Luke
Does this work on any monitor, or only certain ones?
Mimi
The source doesn't specify. Different monitors have different timing standards and refresh rates, so the frequency would vary. You'd need to know your monitor's exact specs.
Mark
Could someone accidentally do this without knowing?
Luke
That's actually a good question the article doesn't answer. If the tool requires you to run it in a browser and display specific patterns, it's not accidental. But whether normal monitor operation could create detectable signals—that's not addressed.
Mimi
The shielding is there for a reason. Normal operation shouldn't leak much. This tool is deliberately crafted to maximize the effect.
Der Puls
- A browser-based tool now lets any standard monitor double as a VHF radio transmitter, requiring nothing beyond the screen already on your desk.
- The technique exploits the pixel clock's precise timing — multiplying resolution and refresh rate to land squarely on a real radio frequency — a mathematical sleight of hand hiding in plain sight.
- Rapid black-and-white pixel patterns force voltage transitions on HDMI and DisplayPort lines, coaxing a detectable signal into the air despite the monitor's shielding working against the effort.
- The signal is genuine but faint — antennas must be held close to the screen, since the entire display chain is engineered to suppress exactly the kind of electromagnetic leakage being exploited.
- The project lands not as a practical communication tool but as a proof of concept: ordinary consumer electronics carry hidden radio potential, accessible to anyone willing to read the timing specifications.
Somewhere between the video signal and the open air, a developer named Efe found a frequency hiding inside the ordinary monitor. By treating the pixel clock not as a display mechanism but as a radio oscillator, he coaxed a standard 1080p screen into transmitting Morse code at 148.500 MHz — no radio hardware required. It is a reminder that the devices we take for granted are built on physical principles that do not care about their intended purpose, and that curiosity about timing diagrams can reveal unexpected dimensions in familiar tools.
Most people reaching for VHF transmission grab a proper radio. Efe reached for a browser instead.
The method turns on the pixel clock — the timing signal driving every modern display. Multiply a monitor's full horizontal and vertical resolution (blanking intervals included) by its refresh rate, and you arrive at a transmission frequency. A standard 1080p display at 60 Hz, using CEA-861 timing, works out to effective dimensions of 2200 by 1125 pixels. Multiply by 60, and the result is 148.500 MHz — a real VHF frequency.
Getting that frequency to radiate is the harder problem. HDMI and DisplayPort cables are engineered to keep stray electromagnetic energy contained. But display the right sequence of black and white pixels — forcing rapid voltage transitions on those lines — and a detectable signal escapes into the air. Efe's tool generates precisely those patterns, flickering the screen in sequences that encode Morse code messages.
The limitation is proximity. Monitors are built to suppress signal leakage, not encourage it, so a receiving antenna must be held very close to the screen to pick anything up. The signal is real; it is simply weak by design.
What the project demonstrates is a kind of hardware judo — redirecting a device's fundamental operating principle toward an entirely unintended purpose. It won't replace a radio, but it reveals how much latent potential sits inside the electronics already on our desks, waiting for someone curious enough to ask what the timing diagrams could do.
Most people who want to transmit on VHF frequencies reach for a handheld radio or a proper rig mounted in their shack. But a developer named Efe has built something stranger: a browser tool that turns your computer monitor into a radio transmitter, no additional hardware required.
The method works by manipulating the pixel clock—the precise timing signal that drives your display. The math is elegant. Take your monitor's horizontal resolution, multiply it by the vertical resolution, then multiply that by the refresh rate. Pay careful attention to the blanking intervals built into your video standard, and you've calculated a transmission frequency. A standard 1080p display running at 60 Hz using CEA-861 timing has effective resolutions of 2200 by 1125 pixels when blanking is factored in. Multiply those numbers by 60, and you get 148.500 MHz—right in the VHF band.
The trick is getting that frequency to actually radiate. Your monitor's HDMI or DisplayPort cable and connectors are engineered to send clean video signals to the display while keeping stray electromagnetic energy contained. But if you display the right pattern of black and white pixels—rapid voltage transitions on those lines—you can coax a detectable signal out into the air. Efe's tool does exactly this, generating patterns designed to transmit simple Morse code messages by flickering your screen in a precise sequence.
The transmitter is available as a browser-based tool that anyone can test. The catch is proximity. Because monitors are built to contain their signals rather than broadcast them, you'll need to hold your radio's antenna very close to the screen to pick up anything at all. The signal is real, but it's weak by design—the monitor, its cables, and connectors are all optimized to keep electromagnetic noise from leaking out into the surrounding environment.
What Efe has demonstrated is a kind of hardware judo: taking a device built for one purpose and repurposing its fundamental operating principle to do something entirely different. It's not practical for actual radio communication, and it certainly isn't a replacement for proper transmission equipment. But it shows how much hidden potential sits in the ordinary electronics on our desks, waiting for someone curious enough to look at the timing diagrams and ask what else they could do.
Bemerkenswerte Zitate
The monitor, connectors, and cable are all built to optimize for clear signal transmission to the display, while preventing signal from leaking out to interfere with surrounding equipment.— Hackaday reporting on Efe's tool
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