Transforming a DIY video transmitter into a WiFi jammer

The proliferation of FPV drones has brought a flood of cheap wireless video tech. After flying and crashing a cheap FPV drone for a bit, [GreatScott] decided to try his hand at building his own video transmitter, which turned out to be a lot harder than expected.

While digital technology has caught up to the FPV world, a lot of systems still use analog video, especially for drone racing. The video quality isn’t great, but it has the advantage of very low latency. The technology is very similar to the old analog TV broadcasts, but mainly uses the 5.8 GHz license-free bands. It is essentially analog video signal, frequency modulated onto a 5.8 GHz carrier signal transmitted through an appropriately sized antenna.

After a brief failed experiment with a simple circuit built from discrete components, [GreatScott] turned his attention to voltage-controlled oscillators (VCO). He bought a couple of 5.8 GHz VCOs from Aliexpress, and created and used a simple opamp circuit to boost the FPV camera video signal to the required input level for the VCO. This failed to produce any identifiable image on his video receiver goggles. In an attempt to confirm that the VCOs produced the desired frequency, he ordered a similar 2.4 GHz VCOs and built a short range (20 cm) WiFi signal jammers. With a signal generator to create a simple input signal, and confirmed that it interfered with his laptop’s WiFi connection.

After more experimentation with other VCOs, the closest [GreatScott] came to success was a barely identifiable image transmitted using a Maxim 2.4 GHz VCO.

Building RF circuits that interfere with the legitimate signal around you, or broadcasting out of band, is generally not a great idea, and could earn you an unpleasant visit from the authorities.

One thing that has always peeved me off is when people are driving around staring at their phones. And then they get mad at me for smashing my horn when they almost hit me or someone else. Then they go right back to staring at their phone again… so i smash my horn again.

But the thought has crossed my mind more than once of being able to smash a button and silently disconnect their phones rather than having my life and property put in peril. Makes me smile, but I would get in more legal trouble than they would for smashing into someone with their vehicle “on accident” when in fact their neglect and inability to focus on operating a machine is the real fault. In my experience, i have been in several accidents due to neglectful drivers and others not following proper use of the road, they get no legal penalty and I end up having to pay the cost due to the fact that insurance is a scam that never pays out without a more expensive lawyer. But then again for those people who are responsible, jamming would likely have them pick up their phone to look at it when their hands free call or podcast or music stops, potentially causing more havock than a single irresponsible driver.

Only tangentially related, but makes me think about every time someone wrecked my car or almost wrecked my car anytime i read about frequency interuption/jamming.