Open Source Software Defined Radio Transceiver

December 21, 2012 by Brian Benchoff 30 Comments

SDR

As the year draws to a close, we must look back and look at the advances in amateur radio this year. The RTL-SDR tuner hack, a USB TV Tuner to create a software defined radio receiver, is one of the greatest hacks of the last 12 months and a great justification for 2012 being the year of software defined radio receivers. 2013 is shaping up to have even more advances in the state of software defined radio. This time we’ll be transmitting as well, possibly with [AE9RB]’s Peaberry SDR transceiver.

The Peaberry SDR transceiver is a kit to both transmit and receive on every HAM band between 160 meters (1.8 MHz) to 17 meters (18 MHz). It does this through a USB interface and a 48kHz, 24-bit interface that is (or will shortly be) compatible with all the major SDR interfaces.

While the Peaberry SDR requires an amateur radio license to operate, we can’t wait to see what else will be coming to the software defined radio scene in the next year.

Thanks [Zach] for sending this one in.

Two Computer Vision Builds From Cornell

December 20, 2012 by Brian Benchoff 6 Comments

land

[Bruce Land], professor at Cornell, is a frequent submitter to our tip line. Usually he sends in a few links every semester from undergraduate electronics courses. Now the fall semester is finally over and it’s time to move on to the more ambitious master’s projects.

First up is a head-mounted eye tracker, [Anil Ram Viswanathan] and [Zelan Xiao] put together a lightweight and low-cost eye tracking project that will record where the user is looking.

The eye tracker hardware is made of two cameras mounted on a helmet. The first camera faces forward, looking at the same thing the user is. The second camera is directed towards the user’s eye. A series of algorithms detect the iris of the user’s eye and overlays the expected gaze position on the output of the first camera. Here’s the design report. PDF, natch.

Next up is a face tracking project implemented on an FPGA. This project started out as a software implementation of a face tracking algorithm in MATLAB. [Thu-Thao Nguyen] translated this MATLAB code to Verilog and eventually got her hardware running on an FPGA dev board. Another design report.

Having a face detection and tracking system running on an FPGA is extremely interesting; the FPGA makes face tracking a very low power and hopefully lower-cost solution, allowing it to be used in portable and consumer devices.

You can check out the videos for these projects after the break.

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Which Way Do Non-polarized Film Capacitors Go? There Is An Answer.

December 19, 2012 by Mike Szczys 11 Comments

orienting-non-polarized-film-caps

If you, like us, thought that capacitor orientation only matters for polarized varieties like electrolytic capacitors you should read through this article. [Bruce Trump] looks at why some film capacitors have a stripe printed on one end and why their orientation can matter.

He has an image rolled into his post showing both axial and dipped capacitors with a black stripe printed on one end of the package. This is an indicator of what is going on inside of the component. The end with the line has a conductive foil layer which acts as a shield. But it seems that this shield will do its job better if you do a better job of designing for the capacitor.

The diagram above shows two op-amp circuits, both using a non-polarized capacitor that will affect the circuit if it receives external interference. [Bruce] discusses various aspects of this phenomenon, mentioning that although these careful layouts can be tested in your designs to prove which has more benefits, simulated applications (using SPICE) will perform exactly the same.

[Bunnie] Builds A Laptop For Himself, Hopefully Us

December 16, 2012 by Brian Benchoff 76 Comments

[Bunnie Huang], creator of the Chumby and artisan of chips and electrons, is building his own completely open source laptop. It’s called the Novena, and is powered by a quad-core ARM CPU, it’s got enough bells and whistles to make any hacker happy including an on-board FPGA, dual Ethernet ports, and enough GPIO pins to do some crazy, crazy stuff.

[Bunnie]’s laptop is an attempt to create a completely open-source laptop capable of some light code development, and web browsing. Every single chip on [Bunnie]’s laptop has a datasheet available (without requiring an NDA, unlike the Raspberry Pi), meaning this laptop might be the beginning of a completely open source laptop.

Officially, this laptop is a one-off project made just for [Bunnie]. He’ll be spending the next few months validating all features on the board and making a proper case. [Bunnie] says a few people may be interested in their own Novena (smart one, that guy), so he might consider a Kickstarter campaign in a few months. Don’t expect it to be cheap, but if you’d like to try your hand at making your own, all the files are up on the Novena wiki.

A Thermal Imaging Camera For Your Phone

December 15, 2012 by Brian Benchoff 23 Comments

When last we heard of a cheap thermal imaging camera accessory for any smart phone, we were blown away at how easily a very expensive electronic device could be replicated with an Arduino and enough know how. Now, that thermal imaging camera is a kickstarter project and provides a cheap way to put a thermal imaging camera in the tool chest of makers the world over.

It’s called the IR-Blue, and simply by connecting your phone to the IR-Blue with Bluetooth, you can overlay the output of a thermal imaging camera on the output of your camera’s phone.

The thermal imaging sensor is basically a low-resolution camera (16 x 4 pixels) for infrared radiation. This sensor is factory calibrated to detect heat in a range between -20 and 300 ˚C. This range allows anyone to easily see where drafts in a house are coming from, where heat in a computer is being generated, or figuring out how to cook a steak.

It’s an awesome and well designed product, so we’ve got to hand it to [Andy] and the IR-Blue team for putting very expensive tools in everyone’s hands.

Rooting Your AT&T U-verse Modem

December 13, 2012 by Mike Szczys 26 Comments

Unhappy with the performance of his U-verse modem [Jordan] decided to dig in and see if a bit of hacking could improve the situation. Motorola makes this exclusively for AT&T and there are no other modems on the market which can used instead. Luckily he was able to fix almost everything that was causing him grief. This can be done in one of two ways. The first is a hardware hack that gains access to a shell though the UART. The second is a method of rooting the device from its stock web interface.

We think the biggest improvement gained by hacking this router is true bridge mode. The hardware is more than capable of behaving this way but AT&T has disabled the feature with no option for an unmodified device to use it. By enabling it the modem does what a modem is supposed to do: translate between WAN and LAN. This allows routing to be handled by a router (novel idea huh?).

LiPo Internal Resistance Measurement Tool

December 12, 2012 by Mike Szczys 13 Comments

lipo-internal-resistance-meter

This is a scratch-build meter for measuring the internal resistance of Lithium Polymer cells. [Bleuer Csaba] uses the LiPo cells for RC vehicles and thet take quite a beating from the motors they’re supplying. This means that he only gets about 100-200 cycles out of each cell. To figure out where one is in its life cycle you can measure the internal resistance where a rising resistance indicates greater age. [Bleuer] mentions that you can buy a meter to do this for you, but what fun is that?

Since he’s rolling his own tool he defined his own parameters for the readings. After experimenting with different loads driven for different test periods he was able to extrapolate an equation that estimates the resistance measurement. As you can see in the clip after the break, this happens very fast. All he has to do is connect the cell and press one button. The measurements are made and various data points are displayed on the quartet of 7-segment displays.

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