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Published on: September 18, 2013 / Comments: None

Man Sized WALL-E Robot

I guess you never grow out of playing with cardboard boxes.  This man sized WALL-E robot just goes to show that you don’t have to spend a lot of money on material just to make a shell for your robots.

The WALL-E robot includes a custom 433Mhz transmitter and receiver which uses Holtek HT12E and HT12D encoder and decoders. Atmega8 and Atmega16 were used to format the data being transmitter. The robot comes to life with the help of motors and pneumatic cylinders.

The soda bottles sure looks hackerish if you ask me. I would like to see more details on the pneumatics used in this project.  See more build photos after the break.


Published on: September 11, 2013 / Comments: None

In the near future, your cell phone may not need batteries

In today’s somewhat creepy too-good-to-be-true technology announcement is this technique called Ambient Backscatter.  In the demo, researchers create 2 devices that neither one takes batteries, yet they are able to communicate to each other.  The devices harness radio waves that are already in the air like TV signals.

By either choosing to absorb or reflect the existing signals, the other device notices either a 1 or a 0.  Thus data transfer wirelessly, without batteries!  These devices have to run on real low power to work, because it’s consuming some of the rf signals to harness as power.  The future for these devices is huge, imagine tons of little smart objects that can communicate, that don’t need batteries!  People are already making small things that sip battery power but they do eventually need batteries.  And typically those devices if they communicate wirelessly they are power hungry.

Amazing technology.  Read more on the writeup on for a more detailed explanation, or watch the video below.


Published on: September 6, 2013 / Comments: None

Reducing the noise on your RTL-SDR

The guys over at SDR for Mariners put together a nice writeup on reducing the electrical interference on the good ol’ cheap RTL-SDR dongle.  When the signal you’re looking for is very faint, you need to remove all of unwanted noise or else your signal gets difficult to separate.  In their case the unwanted signal is in the form of FM radio.

Even if you aren’t a big RF nerd you know some of these remedies already like ferrite beads (you know those giant blocks on the ends of the expensive cables!).  But I’m actually surprised at some of the other ones.  I would have thought that the metal connector around a USB cable would help prevent noise, but according to their tests it was acting like a collector for their intrusive FM signal.  By removing the shield and just connecting the data pins they dropped the noise by 10db.  Not using the extension cable and just plugging straight in is even better.

So the winning combo appears to be all of their methods tested.  A stick wrapped in aluminum foil, touching the metal of the USB plug, connected by a USB extension cable, inside a metal housing.

I’d love to see a picture of the final setup.  Good tips to know when chasing down a faint signal.

Published on: August 27, 2013 / Comments: None

Decoding RF signals like keyfobs with HackRF SDR

Dragorn has a couple of tutorials up on his site about working with the HackRF SDR.  Just like decoding weather satellite signals, decoding wireless remotes and other signals is cool too.  If you’re familiar with the cheap RTL-SDR, then just know the HackRF is like that but more powerful (and can transmit).

Dragorn starts out with part 1: inspecting a pair of car keyfobs.  In this tutorial, he records the signals and inspects them using baudline.  You can see the different encoding mechanisms the 2 different keyfobs use.  Dragorn points out that actually decoding the data is pointless as the data transmitted uses a rolling key pair that constantly changes the data sent for security.


And thus he moves on to part 2: using GNU Radio this time with something that decoding the data might be useful.  For this one he is using a cheapo 433mhz transmitter you would use on an arduino like the ones use in this post.  GNU Radio is a little more complex than baudline.  You get to visually pipe inputs and outputs together for different modules until you achieve the proper filtering and decoding.

Published on: August 26, 2013 / Comments: 1

Receive weather satellite imagry with your SDR

Around 800 km / 500 miles above your head, weather satellites circle Earth, continuously sending back what they see.

You may or may not know, but there are weather satellites pushing un-encrypted images down to earth all the time.  With the right equipment and know-how you can capture these images and take a look.  The guys over at SDR for Mariners put up a little write up on how to do so.

They’re using the infamous cheap RTL-SDR dongle, but almost any SDR would work as long as you can capture the right frequency and have enough bandwidth.  This is being done on windows using SDR Sharp.  This is a great way to learn more about using your SDR, besides aren’t you tired of tuning FM with your SDR ?

Read the full post here.

Published on: August 21, 2013 / Comments: 2

Cheap and easy wireless communications with Arduino

For some odd reason it seems like everyone who starts out doing wireless they do temperature sensors, and Kevin is no exception.  What’s really good in Kevin’s video is he takes the time to explain sending 1′s and 0′s over the rf link and gives you an idea of how the RF communication is actually working.  He also walks you through both sketches, for choosing a simple message encoding algorithm (ie start with this byte, end on this byte).  Good stuff.

The hardware can be purchased pretty cheap from SparkFun, trasmitter here, receiver here.  And Kevin’s made his source sketches available here (transmitter) and here (receiver), but says there are plenty of libraries out there for these modules and his code may not be an example to model yourself after (ha ha ha).

Published on: August 14, 2013 / Comments: None

Spying on your neighbors with rtl-sdr

Unless you’re just upgrading from windows 3.1, you’ve seen the cheap SDR (software defined radio) rtl-sdr project.  SDR’s aren’t new but someone figured out how to turn a cheap sub-20$ dongle into a decent SDR bringing the entry price low enough for everyone to experiment with them.

Every electronic device you own is screaming its name into the infinite void

Melissa Elliott has put together a presentation titled “exploring the world of unintentional radio emissions” that was presented at DEF CON.    After talking about the concept itself, she shows you how almost everything that runs on electricity emits some sort of electronic signature.  That signature can be profiled and sometimes data can be decoded from it.

No it’s not time to break out the tin foil hats or anything but if you really are paranoid, Melissa gives some tips how to shield this information in the form of Faraday cages.  You don’t have to be an old ham radio buff or even a budding electronics engineer to appreciate how cool SDR’s are.