Putting Scores Of Arduinos On The Internet With One Router

June 18, 2012 by Brian Benchoff 10 Comments

Like many hackers of late, [Rick] has been experimenting with connecting Arduinos to the Internet with a disused WiFi router and an installation of OpenWRT. Unlike his fellow makers, [Rick] thought it would be wasteful to dedicate a single router to one Arduino project, so he used a small, low power wireless module to connect up to 30 Arduinos to the Internet.

Just as in a few recent builds (1, 2), [Rick] found an old Fonera router sitting in a box at his local hackerspace. After installing OpenWRT, [Rick] connected a very small wireless module to the router’s GPIO pins and patched the firmware to put an SPI bus on the router.

Now, whenever [Rick] wants to connect an Arduino project to the Internet, all he needs is a $4 radio module. This radio module connects to the router, and the router handles the networking requirements of up to 30 DIY projects.

If you’re looking to build an Internet-enable sensor network, we honestly can’t think of a better or cheaper way of going about it. Nice job, [Rick].

Two Software Defined Radio Hacks From Our Resident SDR Guru

June 16, 2012 by Brian Benchoff 13 Comments

It seem [Balint] is becoming somewhat of a SDR guru around these parts; in the past few months, he’s gotten a USB TV tuner receiver working with GNU Radio, started a software defined radio tutorial YouTube channel, and even used this project to listen in on conversations between airplanes and air traffic control. This time, [Balint] is back ~~using this cheap USB TV tuner for~~ radio direction finding and running HDSDR in Linux and OS X.

[Balint]’s radio direction finding presentation goes over traditional means of direction finding using the doppler effect and mechanically rotated antennas. Because [Balint] is dealing with frequencies around 150MHz (about 2 meter wavelength), building a physical direction finding setup requires spinning antennas at around 40,000 RPM; much to fast for any hardware build. [Balint]’s solution was to attach 4 antennas around the circumference of a circle and electronically switch between them many thousands of times a second. [Balint] put up a wiki page going over all the theory and implementation details of his build.

[Balint] also put wrote up a neat app to control software defined radios – including the Realtek TV dongle – over a network. Spread over a wide enough geographic area, it could become extremely easy for anyone to play air traffic controller. The BorIP Server can also be used to run HDSDR in Linux and OS X under Wine; just connect HDSDR to the network loopback on the same machine, and you get around Wine’s distaste for accessing hardware natively.

Awesome work, and we can’t wait to see what comes out of [Balint]’s laboratory next.

Edit: instead of the dongle, [Balnt] is using a ‘real’ software radio board. A lot of people are messaging him asking if the same method of direction finding is possible with the dongle. Here’s what [Balint] has to say:

The trick, as I see it, would be to create some (more or less simple) additional hardware to take the clock signal straight off the dongle’s on-board oscillator and divide it down for use with the antenna switch, i.e. 28 MHz à tens of kHz (this is the bit that’s done in ‘software’ on the FPGA). One problem still remains however: the counter needs to remain calibrated against the known direction the antenna was pointing at the time – otherwise a stop/start of the data stream from the dongle will mean the direction will go out of sync by 90/180/270 degrees each stop/start. Perhaps someone will figure out an elegant solution for this slight hurdle!

So there you go. Up for a challenge?

A Simple RF Signal Strength Meter

June 12, 2012 by Jeremy Cook 18 Comments

[Scott] wrote in to us with his simple, but well done RF signal strength meter. As he points out in his post, sometimes an Arduino is overkill, so a Picaxe 08M was used instead. Apparently this was a refresh of a high school project that he did. Certainly many of us would have liked to go to that high school!

An interesting part of this project is how he used a laser cutter to produce his PCB traces. This was done by applying black paint to the copper on his board and cutting everywhere he didn’t want copper traces. The results were quite good, and should work well when this project is finalized in an enclosure

Check out the video after the break to see this circuit in action. He explains the build in it, but if you just want to see the signal strength lights come on, fast forward to around 2:25. Continue reading “A Simple RF Signal Strength Meter” →

[Balint] Is Starting A Software-defined Radio Tutorial Series

June 11, 2012 by Brian Benchoff 26 Comments

A few months ago, we saw a hack where a $20 USB TV tuner was transformed into a software-defined radio capable of reading GPS signals, listening to radio transmissions between aircraft and a control tower, and even a simple FM radio. This project is a perfect introduction to the RTL-SDR and Ham radio scene, but getting these projects up and running can be a bit overwhelming for anyone who hasn’t played around with this before. [Balint] is tackling this problem head on with a series of YouTube tutorials to get SDR noobs up and running with GNU Radio and the Realtec USB TV tuner.

To demonstrate the power of software-defined radio, [Balint] is using GNU Radio and the USB TV tuner that started it all, the Ezcap EZTV668 (conveniently back in stock at DealExtreme, but other options exist). Because software-defined radio is a touch confusing for a beginner to wrap their head around, [Balint] is beginning his tutorial series by explaining radio sources, sinks, and the GNU Radio interface.

Already, [Balint] has put up 5 tutorials and made the flowgraph files available in his gr-baz project. He’s doing a wonderful job opening up the software-defined radio scene to beginners, but he’s still looking for some feedback. If you have a suggestion on what [Balint] should cover next, leave a note in the YouTube comments and we’re sure [Balint] will get around to that eventually.

Reading RFID Cards From Afar Easily

May 27, 2012 by Brian Benchoff 41 Comments

RFID hacking has been around for years, but so far all the builds to sniff data out of someone’s wallet have been too large, too small a range, or were much too complicated for a random Joe to build in his workshop. [Adam]’s RFID sniffer gets around all those problems, and provides yet another reason to destroy all the RFID chips in your credit cards.

The project was inspired by this build that took a much larger RFID reader and turned it into a sniffer capable of covertly reading debit cards and passports from the safety of a backpack or briefcase. [Aaron]’s build uses a smaller off-the-shelf RFID reader, but he’s still able to read RFID cards from about a foot away.

[Aaron]’s build is very simple consisting of only an Arduino and SD card reader. [Aaron] is able to capture all the data from an RFID card, write that data to the SD card, and emulate a card using his RFID cloner.

What’s really impressive about the build is that [Aaron] says he’s not a programmer or electrical engineer. His build log is full of self-denegration that shows both how humble [Aaron] is and how easy it is for anyone with the requisite skill set to clone the bank card sitting in your wallet. We don’t know about you, but you might want to line your wallet with aluminum foil from now on.

FTA Dish Used To Receive L-band Amateur Radio

May 21, 2012 by Mike Szczys 11 Comments

[David Prutchi] has an FTA (free-to-air) satellite dish. This means he can tune and watch freely available satellite television feeds. But this sounds much better than it actually is. There isn’t much that’s broadcasted unecrypted from satellites with the exception of a collection of religious channels. But he still uses the dish by using the FTA satellites to calibrate the alignment, then repositioning it to receive L-Band radio transmissions with his own add-on hardware. In the image above it’s the spiral of wire attached to the dish’s collector.

The satellite transmissions are picked up on the KU-band by an aftermarket horn that [David] purchased for this purpose. To add his own helix receiver he cut a square mounting plate that fits around the horn. This plate serves as a reflector and ground plane, and also hosts the helix connector which picks up the L-band transmissions. He had to be creative with routing the first few inches of the helix but it looks like he manages to get some pretty good performance out of the hardware.

[via Hacked Gadgets]

Controlling Robots With A TRS-80

May 15, 2012 by Brian Benchoff 12 Comments

[DJ Sures], mastermind behind the EZ-B Bluetooth Robot controller, sent in a really interesting build where he controls a robot with a 1983 TRS-80 computer.

The robot in question is [DJ Sures]’ adorable WALL-E we’ve seen before. WALL-E is controlled through a Bluetooth connection to a desktop PC with the EZ-Builder hardware and software package.

To get the Trash-80 talking to WALL-E, [Sures] connected a tiny Bluetooth module to the TX pin of the 6402 UART. It’s a very, very simple modification that adds a Bluetooth serial connection to one of the first notebook computers. After syncing the TRS-80 and WALL-E to the computer running EZ-Builder, it’s a piece of cake to make the robot respond to the clanging of a 30-year-old keyboard.

There’s a video of [DJ Sures] going over his build after the break with a wonderful demo of WALL-E freaking out to a little dubstep. Check that out after the break.

Continue reading “Controlling Robots With A TRS-80” →