Hacking The R-390A Military Shortwave Radio Receiver To Transmit As Well

June 6, 2013 by Mike Szczys 12 Comments

hacking-r390a-radio

After getting his hands on this relic [Gregory Charvat] manage to hack it, converting the receiver into a transceiver.

It may be old, but the R-390A is nothing to scoff at. It’s abilities include AM, code, and FSK operation from 500 kHz to 32 MHz. But it is a receiver with no way of transmitting on the same bands. This is where [Gregory’s] hack comes into play. He rerouted the variable-frequency oscillator feed inside of the R-390A in order to use his 20M single-sideband unit. Basically what this does is allow him to control everything from the 390, using the microphone from the SSB — along with some switching hardware — to transmit his own messages.

His demo video starts with him making a few contacts using the hacked equipment. He then spends some time at the whiteboard explaning the changes. This portion went over our heads, but it becomes more clear when he cracks open the case and shows the actual modifications.

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2013 LayerOne Badge Hacking Contest Winner

June 1, 2013 by Mike Szczys 20 Comments

[Dynotronix] wrote in to share the news that he won the 2013 LayerOne badge hacking contest. In addition to the good news he included a description of his badge hack.

We got a good look at the hardware included on the badge several days ago. You may remember that it’s outfitted with footprints for 48 LEDs around the perimeter which are driven by two ICs. Looking at the image above it’s hard to miss the fact that [Dyno] didn’t populate any of that. He went right for the power of the XMEGA processor to analyze and generate signals.

But what specifically can you do with the signal this thing generates? Turns out a rather simple circuit can make it into a transmitter. [Dyno] concedes that it’s a remarkably finicky setup, but just a few components on a scrap of copper clad turned this into an FM transmitter. Check out the video where you can hear the sweeping alarm-type sounds pushed to an FM radio via his voltage controlled oscillator circuit which has a range of about fifteen feet.

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Raspberry Pi Helps With 2.4GHz Home Automation

May 30, 2013 by Mike Szczys 15 Comments

Wanting to extend the capabilities of the radio frequency devices in his home [Kalle Löfgren] turned a Raspberry Pi into an RF control hub. We’ve seen some of his home automation work in the past. In his media room he built a universal remote base station which used the same RF board as in this project. The main difference is that before he went with an AVR microcontroller and this time he’s upgrade to a Raspberry Pi board.

The RPi brings a lot more to the table. Notably, the scripting (whose output is shown above) and networking features. His radio board is an nRF24L01 which he talks to via the SPI protocol. The Raspberry Pi has no problem talking to SPI devices through its GPIO header. [Kalle] just needed to do a bit of setup to configure the pin modes.

A Python script lets him sent commands using his keyboard, but this can also be automated. Combine that with the TCP server script he wrote and it opens up the a wide range of configurations to switch or talk to any device operating on the 2.4 GHz band.

Detecting Galactic Rotation With Software Defined Radio

May 26, 2013 by Brian Benchoff 27 Comments

Last summer in the heyday of software defined radio via USB TV tuners we asked hackaday readers a question: Is anyone using everyone’s favorite method of SDR for radio astronomy? It took nearly a year, but finally there’s an awesome project to turn a USB TV tuner into a radio telescope. It’s from the fruitful mind of [Marcus Leech] (PDF warning), and is good enough to detect the rotation of the galaxy with a three-foot satellite dish.

News of [Marcus]’ work comes to us from [Carl] over at RTL-SDR.com who has been keeping tabs on the advances of building a radio telescope in a backyard. He’s been collecting a lot of interesting tidbits including this gif showing an arm of the galaxy entering and leaving [Marcus]’ telescope’s field of view over the course of a few hours.

Not only can [Marcus]’ telescope record continium measurements – basically, a single-pixel camera sensitive to only one frequency – it can also produce spectral plots of the sky. Combine the ability to measure multiple frequencies at the same time with the Doppler effect, and [Marcus] can measure the rotation of the galaxy with a USB TV tuner. That’s just awesome in our humble opinion.

If you already have an RTL-SDR TV tuner and a largish satellite dish, [Marcus]’ project should be fairly inexpensive to replicate; the feed assembly is made out of a coffee can, the amplifiers are repurposed satellite television equipment, and all the software – [Marcus]’ own simple_ra tool for GNU Radio – is open source. Of course with a 3 foot diameter dish, it will be impossible to replicate the data from huge radio telescopes. Still, it’s an impressive piece of work that leaves us searching craigslist for an old C-band dish.

Listening To Aircraft Transponders With A Raspberry Pi

May 23, 2013 by Brian Benchoff 31 Comments

Last year’s big hack was software-defined radio; a small USB TV tuner that could listen in on radio broadcasts anywhere between 64 and 1200 MHz. This year, it’s all about the Raspberry Pi, so it’s surprising we’re only just now seeing a mashup of these two pieces of hardware. [Corq] is using a Raspi and RTLSDR TV tuner to listen in on aircraft transponders, and getting a whole bunch of data from aircraft flying overhead.

Even though the ADS-B decoder [Corq] is using is written for OS X, he’s reading the data coming from the USB TV tuner over the network with a program called Dump1090. This program allows [Corq] to attach his SDR to a Raspbery Pi and put it somewhere the antenna will get good reception – an attic, or an outdoor weatherproof case – and stream data to his desktop over a WiFi or network connection.

With a USB TV tuner and a Raspberry Pi, [Corq] is able read the tail numbers, altitude, latitude, longitude, speed, heading, and even the type of aircraft currently flying over his house. That’s cool enough, but the fact that he can effectively do this over the Internet makes it a brilliant hardware mashup.

Wireless Microcontroller/PC Interface For $3

May 19, 2013 by Brian Benchoff 48 Comments

Sending data from a microcontroller to a PC usually requires some sort of serial connection, either through fiddly on-chip USB, FTDI chips, or expensive radio ICs. [Scott] didn’t want to deal with this when creating a network of wireless temperature sensors, so he hacked up a few cheap 433 MHz radio transmitters and receivers to transmit data to a PC for about $3.

After sensor data is collected on a microcontroller and sent over radio, there’s still the issue of getting it into a PC. For this, [Scott] piped the data into the microphone port of a cheap USB sound card. We’ve seen this trick before both in the world of microcontrollers and loading programs onto a Commodore 64 via a cassette interface.

Once the data is sent into the sound card, it’s decoded with a a small Python app. Given the range and quality of the RF transmitters and receivers [Scott] says it’s not an extremely reliable way to send data to a PC. It is cheap, though, and if you need to read sensors wirelessly on a budget, it’s hard to do much better.

Check out [Scott]’s demo of his creation below.

[youtube=http://www.youtube.com/watch?v=GJHFldPwZvM&w=580]

Retrotechtacular: First Laser Transmitter Built 50 Years Ago

May 14, 2013 by Mike Szczys 15 Comments

helium-neon-laser-transmitter

Most of the time we feature hokey film footage in our Retrotechtacular series, but we think this hack is as cool today as it was fifty years ago. [Clint] wrote in to tell us about Operation Red Line. It was an experiment performed May 3rd and 4th, 1963, which means the 50th anniversary just passed a few weeks ago. The hack involved sending data (audio in this case) over long distances using a laser. But back then you couldn’t just jump on eBay and order up the parts. The team had to hack together everything for themselves.

They built their own helium-neon laser tube, which is shown on the right. The gentlemen involved were engineers at a company called Electro-Optical System (EOS) by day, and Ham radio enthusiasts by night. With the blessing of their employer they were able to ply their hobby skills using the glass blowing and optical resources from their work to get the laser up and running. With that side of things taken care of they turned to the receiving end. Using a telescope and a photomultipler they were able to pick up the beam of light at a distance of about 119 miles. The pinnacle of their achievement was modulating audio on the transmitter, and demodulating it with the receiver.

[Clint] knows the guys who did this and wrote up a look back at the project on his own blog.