Radio Hacks

1435 Articles

Guest Post: Try Radar For Your Next Project

February 24, 2014 by 77 Comments

Sensors. The low-end stuff that we can get our hands on usually suffers from poor range, lack of sensitivity, and no way to characterize what the target is. But today we can use the good stuff that, until recently, was only available to military: radar. In this post we will discuss how radar works, commercially available small radar devices, and where to learn more to help make it easy to add radar to your next project. Reach out and sense something!
Continue reading “Guest Post: Try Radar For Your Next Project” →

Audio Networking With GNU Radio

February 19, 2014 by 31 Comments

fsk

Thought GNU Radio was just for radio? Think again. [Chris] has been hard at work turning the signal generation and analysis of the best tool for software defined radio into a networking device for speakers and a microphone.

The setup uses GNU Radio to generate a carrier signal whose frequency is modulated with a data stream. With this modulated signal piped over a laptop’s speakers, [Chris] is able to send UDP packets across his desk using nothing but sound.

[Chris] had recently used a similar technique to transmit data via audio with GNU Radio, but this latest build is a vast improvement; this is now a duplex networking, meaning two computers can transmit and receive at the same time.

In the end, [Chris] created a strange, obsolete device called a “modem”. It’s not exactly fast; sending ‘Hello World’ takes quite a bit of time, as you can see in the video below.

Continue reading “Audio Networking With GNU Radio” →

Call For Hams And Hackers: Welcome ICE/ISEE-3 Home

February 14, 2014 by 76 Comments

ISEE-3, one of America’s most dedicated space exploration vessels is on its way home. Unfortunately, when it gets here, no one will be talking to it. NASA decommissioned the equipment needed to communicate with the satellite nearly 15 years ago. [Emily Lakdawalla] at the planetary society has been following the long traveled probe for years. Her recent article on the topic includes the news that NASA essentially gave up the battle before it even started.

Originally named International Sun/Earth Explorer 3 (ISEE-3), the spacecraft was launched atop a Delta rocket on August 12, 1978. Its mission was to study interaction between the Earth’s magnetic field and solar wind. As part of this mission ISEE-3 became the first spacecraft to enter halo orbit. It did this by positioning itself at Lagrangian point L1, directly between the sun and the Earth. In 1982, scientists on earth were preparing for the 1986 flyby of Halley’s Comet. ISEE-3 was repurposed as a comet hunter, and renamed International Cometary Explorer (ICE). The craft flew back to Earth and entered lunar orbit, coming within 120km of the moon’s surface. It used this momentum to achieve a heliocentric orbit, on track for two comet encounters. ICE/ISEE-3 encountered Comet Giacobini-Zinner on September 11, 1985, collecting data and becoming the first spacecraft to fly through a comet’s plasma tail. While not considered part of the Halley Armada, ICE/ISEE-3 took measurements as it passed within 28 million km of Comet Halley’s nucleus. Since then, ICE/ISEE-3 has continued on its 355 day heliocentric orbit. It studied coronal mass ejections in the early 90’s, before being shut down in May of 1997. Follow us past the break to learn ICE/ISEE-3’s fate.

Continue reading “Call For Hams And Hackers: Welcome ICE/ISEE-3 Home” →

From Vacuum Cleaner Hacking To Weather Station Reverse Engineering

February 11, 2014 by 19 Comments

spectrum

[Spock] wanted to do a little reverse engineering of his Miele brand remote control vacuum cleaner, so he broke out his DVB-T SDR dongle to use as a spectrum analyser. Sure enough, he found a 433.83Mhz signal that his vacuum cleaner remote control was using, but to his surprise, he found a stray QAM256 signal when he expected an ASK  only one.

After a little detective work, [Spock] eventually tracked it down to a cheap weather station he had forgotten about. The protocol for the weather station was too compelling for him to go back to his vacuum cleaner, though. After downloading an rc-switch Arduino library and making a quick stop at his local radio shack to get a 433.92 radio receiver to decode the signal, he reverse engineered the weather station so he could digitally record the temperature output. The Arduino rc-switch library proved unable to decode the signal, but some Python work helped him get to the bottom of it.

With software defined radio becoming more accessible and common place, hacks like these are a nice reminder just how wired our houses are becoming.

Improve Your HT Ham Radio By Adding A Counterpoise Antenna Wire

February 8, 2014 by 38 Comments

counterpoise

We found an interesting tip that might just improve the performance of those small affordable handheld ham radios called a “Handy Talky” or HT for short in ham vernacular. [RadioHamGuy] posted an interesting video on adding a counterpoise antenna wire to an HT. He claims it will noticeably improve both transmit and receive by making a quarter-wave monopole into a makeshift dipole antenna system.

Per his instructions you basically add a short wire to the antenna’s outer ground connection or to an equivalent case screw that’s electrically connected to the antenna’s ground side. Apparently this can be referred to as a Tiger Tail and does make it look like your HT has a tail. You would construct a counterpoise antenna wire 11.5 inch for VHF, 6.5 for UHF and about 19.5 inches for an OK performing dual band VHF/UHF radio.

Normally with a handheld radio the counterpoise (ground) is your own body as you are holding the HT. This is because the capacitance of your body makes a good counterpoise under normal conditions. It would be interesting to hear what others find for performance when adding a counterpoise antenna wire.

You can watch [RadioHamGuy’s] full construction tutorial video for multiple radio types after the break.

Continue reading “Improve Your HT Ham Radio By Adding A Counterpoise Antenna Wire” →

Pi-Powered Radio Over IP

February 6, 2014 by 12 Comments

Pi

[KP4TR] connected a Raspberry Pi to a small, cheap handheld radio, allowing anyone within a few miles of his house to connect to amateur radio operators all around the world.

For the hardware, [KP4TR] is using a Raspi, a Baofeng BF-888s 400MHz – 470MHz walkie-talkie radio, a USB sound card, and a pair of transformers for the 5V and 3.7V lines. All this is tucked away in a remakably vintage-looking plate and standoff enclosure, complete with acorn nuts and an RGB LED connected to the Raspi’s GPIO to indicate whether the radio is transmitting or receiving.

The software used is SVXLink, a Linux port of the Echolink software. This app allows hams the world over to connect to very distant radios over the Internet.

You can check out the video demos of the system below.

Continue reading “Pi-Powered Radio Over IP” →

Verifying A Wireless Protocol With RTLSDR

January 31, 2014 by 1 Comment

rtlsdr_nrf905_rtlizer

[Texane] is developing a system to monitor his garage door from his apartment. Being seven floors apart, running wires between the door and apartment wasn’t an option, so he turned to a wireless solution. Testing this wireless hardware in an apartment is no problem, but testing it in situ is a little more difficult. For that, he turned to software defined radio with an RTLSDR dongle.

The hardware for this project is based around a TI Stellaris board and a PTR8000 radio module. All the code for this project was written from scratch (Github here), making it questionable if the code worked on the first try. To test his code, [Texane] picked up one of those USB TV tuner dongles based around the RTL2832U chipset. This allowed him to monitor the frequencies around 433MHz for the packets his hardware should be sending.

After that, the only thing left to do was to write a frame decoder for his radio module. Luckily, the datasheet for the module made this task easy.

[Texane] has a frame decoder for the NRF905 radio module available in his Git. It’s not quite ready for serious applications, but for testing a simple radio link it’s more than enough.