We Need To Have A Chat About Something Important

Yes, I really did print this the day before the story broke.
Yes, I really did print this the day before the story broke.

With hindsight, I picked the wrong day to 3D print a Cap’n Crunch whistle downloaded from Thingiverse. I was covering the hackspace textile evening, so I set the Ultimaker going and headed off to spend my evening making a laptop pouch. My whistle, a reasonable reproduction of the famous cereal packet novelty whose 2600 Hz tone allowed special access to American telephone networks, was ready for me to take away as I headed home.

The next day, there it was. The legendary phreaker [John Draper], also known as [Captain Crunch] after his use of that free whistle, was exposed as having a history of inappropriate conduct towards teenage boys and young men who he encountered in his tours of the hacker community as a celebrity speaker.

My whistle will no longer go on a lanyard as a piece of cool ephemera, it’s sitting forlornly on my bench. The constant procession of harassment allegations that have been in the news of late have arrived at our doorstep. Continue reading “We Need To Have A Chat About Something Important”

A Teardown Of Something You Should Not Own

GPS jammers are easily available on the Internet. No, we’re not linking to them. Nevertheless, GPS jammers are frequently used by truck drivers and other people with a company car that don’t want their employer tracking their every movement. Do these devices work? Are they worth the $25 it costs to buy one? That’s what [phasenoise] wanted to find out.

These tiny little self-contained boxes spew RF at around 1575.42 MHz, the same frequency used by GPS satellites in high Earth orbit. Those signals coming from GPS satellites are very, very weak, and it’s relatively easy to overpower them with noise. That’s pretty much the block diagram for these cheap GPS jammers — put some noise on the right frequency, and your phone or your boss’s GPS tracker simply won’t function. Note that this is a very low-tech attack; far more sophisticated GPS jamming and spoofing techniques can theoretically land a drone safely.

[phasenoise]’s teardown of the GPS jammer he found on unmentionable websites shows the device is incredibly simple. There are a few 555s in there creating low-frequency noise. This feeds a VCO with a range of between 1466-1590 MHz. The output of the VCO is then sent to a big ‘ol RF transistor for amplification and out through a quarter wave antenna. It may be RF wizardry, but this is a very simple circuit.

The output of this circuit was measured, and to the surprise of many, there were no spurious emissions or harmonics — this jammer will not disable your cellphone or your WiFi, only your GPS. The range of this device is estimated at 15-30 meters in the open, which is good enough if you’re a trucker. In the canyons of skyscrapers, this range could extend to hundreds of meters.

It should be said again that you should not buy or use a GPS jammer. Just don’t do it. If you need to build one, though, they’re pretty easy to design as [phasenoise]’s teardown demonstrates.

Arduino Saves Game Boy Camera

[Brian Khuu] bought a few Game Boy cameras on the Internet and found that they still had pictures on them from the previous owners. The memory in the camera has a backup battery and if that battery dies, the pictures are history, so he decided to mount a rescue operation.

He knew the protocol for how the Game Boy talked to the companion pocket printer was available, so he used an Arduino and a Web browser to extract the photos. The resulting code is on GitHub if you want to save your pictures. Although [Brian] didn’t have to crack the protocol, he does offer a good explanation of it. There’s even some sniffed displays. The Arduino does all the communications and fools the game into thinking it is the companion printer. However, it simply streams the data out and a Javascript decoder handles the actual decoding. In fact, in the blog post, you can enter data, click a button, and see the resulting Game Boy picture.

It works, but [Brian] did run into a few problems. For one thing, the devices don’t seem to use any flow control so he had no choice but to keep up with the Game Boy. Also, there is a CRC he could not correctly decode. However, the pictures look good — well, as good as Game Boy pictures look, at least. So he did get results.

We’ve seen this done with a PC before. If you are more interested in the reverse, by the way, you can use a real Game Boy printer to print from an Arduino.