Eye-Fi Teardown

February 1, 2009 by Eliot 44 Comments

eye-fi

[les robots] had a defective Eye-Fi card on his hands and when a replacement was sent, he was told to destroy the original. What better way to ‘destroy’ something than opening the case? The Eye-Fi is an SD card with a builtin WiFi radio so it can upload images while remaining in camera. One version uses Skyhook’s location service to geotag photos. You can see a few photos of the dismantled card on Flickr. The board is manufactured by Wintec. The wireless side is handled by Atheros’ ROCm, the same low power Radio-on-Chip module you would find in a mobile phone. The flash memory comes from Samsung and the antenna is along the back edge, where it has the best chance of getting signal.

UHF Power Harvesting

January 29, 2009 by Eliot 15 Comments

hdpowerharvesting

[Alanson Sample] and [Joshua R. Smith] have been experimenting with wireless power transfer for their sensing platform. Their microcontroller of choice is the MSP430, which we used on our e-paper clock. They chose it specifically for its ability to work with low voltages and they discus its specific behavior at different voltages. The first portion of their paper uses a UHF RFID reader to transmit to the sensor’s four stage charge pump. They added a supercap to provide enough power for 24 hours of logging while the node isn’t near a reader. For the second half of the paper, they use a UHF antenna designed for digital TV with the same circuit and pointed it at a television tower ~4.1km away. It had an open circuit voltage of 5.0V and 0.7V across an 8KOhm load, which works out to be 60uW of power. They connected this to the AAA battery terminals of the thermometer/hygrometer pictured above. It worked without issue. The thermometer’s draw on a lab power supply was 25uA at 1.5V.

It’s an interesting approach to powering devices. Do you have an application that needs something like this? For more on wireless power, checkout this earlier post on scratch building RFID tags.

[via DVICE]

TEMPEST: A Signal Problem

January 25, 2009 by Eliot 12 Comments

TEMPEST is the covername used by the NSA and other agencies to talk about emissions from computing machinery that can divulge what the equipment is processing. We’ve covered a few projects in the past that specifically intercept EM radiation. TEMPEST for Eliza can transmit via AM using a CRT monitor, and just last Fall a group showed how to monitor USB keyboards remotely. Through the Freedom of Information Act, an interesting article from 1972 has been released. TEMPEST: A Signal Problem (PDF link dead, try Internet Archive version) covers the early history of how this phenomenon was discovered. Uncovered by Bell Labs in WWII, it affected a piece of encryption gear they were supplying to the military. The plaintext could be read over that air and also by monitoring spikes on the powerlines. Their new, heavily shielded and line filtered version of the device was rejected by the military who simply told commanders to monitor a 100 feet around their post to prevent eavesdropping. It’s an interesting read and also covers acoustic monitoring. This is just the US history of TEMPEST though, but from the anecdotes it sounds like their enemies were not just keeping pace but were also better informed.

[via Schneier]

WiFi Theremin

January 23, 2009 by Eliot 9 Comments

The fine folks at Midnight Research Labs have put together a new toy for you to play with. It’s a Python script that makes your WiFi hardware behave more like a theremin. Based on the pyaudio library it monitors the signal strength of the AP you’re connected to and changes the tone accordingly. There’s a sample embedded above (direct link). If you have a second interface, you can use it to modulate the volume. It’s an interesting trick, but they say that there’s enough latency that it would be hard to play actual music with it.

External Antenna On Panasonic CF-R1

January 21, 2009 by Caleb Kraft 15 Comments

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[Steven] managed to get his hands on a Panasonic CF-R1 for pretty cheap. Though it is a decently powerful machine, it was built in 2002 and didn’t come with an internal wireless card. It did, however have a mini-PCI slot. [Steven] promptly installed a wireless card, but found the internal antenna lacking. The solution was to custom mount an external antenna. Mounting it was fairly easy, he removed the phone jack and epoxied the connector in its place. The reception was greatly improved. He says he went from seeing 6 access points to 31 as soon as he installed it. Similar things have been done to the Eee PC 900.

Hack A Walkie Talkie For Music

January 14, 2009 by Caleb Kraft 40 Comments

radio1

[nepheron] shows us how he hacked his walkie talkie to broadcast music. While using this to broadcast music is possibly illegal, it could be used to make actual upgrades to your system as well. He has replaced the microphone input with a headphone cable and extended the antenna. It is only mono, and he states it will only run for a minute before shutting off, so there is definitely room for improvement.

Wireless BlinkM Control

January 10, 2009 by Eliot 5 Comments

blinkm

[John] has been working with several BlinkM RGB devices. He’s created a controller to talk to each of the BlinkMs wirelessly and change their behavior. The core is an old relay tester box used to test telephone circuits. Each of its four knobs are connected to the analog inputs on the Arduino. The signal is transmitted using RFlink devices. Each BlinkM is paired with an ATmega168 and receiver. The control box also has a switch to send the same signal to all of the devices at the same time. The transmit and receive code are available on his site. You can find a video of it embedded below.

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