DIY Video Transmitter Turned 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 jammer. 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. If you have any ideas on what is missing in the VTX circuit, drop them in the comments below.

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. If you want to build your own digital video transmission, take a look at the Wifibroadcast project.

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Hackaday Podcast 045: Raspberry Pi Bug, Rapidly Aging Vodka, Raining On The Cloud, And This Wasn’t A Supercon Episode

Hackaday editors Mike Szczys and Elliot Williams talk over the last three weeks full of hacks. Our first “back to normal” podcast after Supercon turns out to still have a lot of Supercon references in it. We discuss Raspberry Pi 4’s HDMI interfering with its WiFi, learn the differences between CoreXY/Delta/Cartesian printers, sip on Whiskey aged in an ultrasonic jewelry cleaner, and set up cloud printing that’s already scheduled for the chopping block. Along the way, you’ll hear hints of what happened at Supercon, from the definitive guide to designing LEDs for iron-clad performance to the projects people hauled along with them.

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

Continue reading “Hackaday Podcast 045: Raspberry Pi Bug, Rapidly Aging Vodka, Raining On The Cloud, And This Wasn’t A Supercon Episode”

Hackaday Prize Entry: Don’t Build This

The ESP8266 is a remarkable piece of hardware. What we originally thought — and what was originally marketed as — a simple UART to WiFi bridge with Hayes modem commands has turned into one of the best embedded platforms around. It’s a powerful little microcontroller, it has WiFi, and it can send raw frames. That last bit is awesome, because it allows for some mischief or mirth making, depending on your point of view.

For his Hackaday Prize entry, [Tejas] is building a WiFi Jammer with an ESP8266. It’s a small device that is able to disconnect anyone from a WiFi AP. Should you build it? No. Can you? Sure, why not.

The code for this WiFi hacking tool is taken from the creator of the ESP8266 deauth toolkit, [spacehuhn], although [Tejas] is violating the license for [spacehuhn]’s (non-Open Source) code. This fantastic piece of firmware uses management packets to send a deauthentication frame, effectively allowing anyone to disconnect any device from a WiFi router. Why would anyone want to do this? Mischief, of course, but there are also a few techniques that could allow an attacker to get a password for the WiFi.

While there are ways to protect against deauth attacks, most routers don’t have management-frame protection enabled. In any event, we’re going to see exactly how annoying deauth attacks can be this week at DEF CON. The smart money is on a small percentage of DEF CON attendees lulzing about with ESPs and the Caesar’s CTO being very, very unhappy.