Radio Hacks

1334 Articles

HamShield Puts Your Arduino On The Radio

July 13, 2015 by 43 Comments

Anybody can grab a USB TV tuner card and start monitoring the airwaves, but to get into the real meat of radio you’ll need your amateur radio license. Once you have that, the bandwidth really opens up… if you can afford the equipment. However, [spaceneedle] and friends have dramatically lowered the costs while increasing the possibilities of owning a radio by creating this ham radio shield for the Arduino.

The HamShield, is a versatile shield for any standard Arduino that allows it to function like an off-the-shelf radio would, but with a virtually unlimited number of functions. Anything that could be imagined can be programmed into the Arduino for use over the air, including voice and packet applications. The project’s sandbox already includes things like setting up mesh networks, communicating over APRS, setting up repeaters or beacons, monitoring weather stations, and a whole host of other ham radio applications.

HamShield operates on a wide range of frequencies and only uses a 250 mW amplifier. The power draw is small enough that the HamShield team operated it from a small solar panel, making it ideal for people in remote areas. The project is currently gathering funding and has surpassed their goal on Kickstarter, branding itself appropriately as the swiss army of amateur radio. The transceiver seems to be very robust, meaning that the only thing standing in the way of using this tool is simply writing the Arduino code for whatever project you want to do, whether that’s as a police scanner or even just a frequency counter. And if you want to follow along on hackaday.io, the project can be found here.

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CCCamp 2015 Rad1o Badge

July 12, 2015 by 9 Comments

Conference badges are getting more complex each year. DEFCON, LayerONE, Shmoocon, The Next Hope, Open Hardware Summit, The EMF, SAINTCON, SXSW Create, The Last Hope, TROOPERS11, ZaCon V and of course the CCC, have all featured amazing badges over the years. This years CCCamp 2015 rad1o badge is taking things several notches higher. The event will run from 13th through 17th August, 2015.

The rad1o Badge contains a full-featured SDR (software defined radio) transceiver, operating in a frequency range of about 50 MHz – 4000 MHz, and is software compatible to the HackRF One open source SDR platform. The badge uses a Wimax transceiver which sends I/Q (in-phase/quardrature-phase) samples in the range of 2.3 to 2.7 GHz to an ARM Cortex M4 CPU. The CPU can process the data standalone for various applications such as FM radio, spectrogram display, RF controlled power outlets, etc., or pass the samples to a computer using USB 2.0 where further signal processing can take part, e.g. using GnuRadio. The frequency range can be extended by inserting a mixer in the RF path. Its got an on-board antenna tuned for 2.5GHz, or an SMA connector can be soldered to attach an external antenna. There’s a Nokia 6100 130×130 pixel LCD and a joystick, which also featured in the earlier CCCamp 2011 badge known as the r0ket.

A 3.5mm TRRS audio connector allows hooking up a headphone and speaker easily. The LiPo battery can be charged via one of the USB ports, while the other USB port can be used for software updates and data I/O to SDR Software like GnuRadio. Check out the project details from their Github repository and more from the detailed wiki which has information on software and hardware. There’s also a Twitter account if you’d like to follow the projects progress.

This years Open Hardware Summit also promises an awesome hackable badge. We’ll probably feature it before the OHS2015 conference in September.

Thanks to [Andz] for tipping us off about this awesome Badge.

Pico Space Balloon Circumnavigates The Globe, Twice

July 5, 2015 by 13 Comments

We’ve reported on “space” balloons before. Heck, some of us have even launched a few. Usually they go way up in the air, take some cool pictures, and land within driving (and retrieving) distance the same afternoon. You get often amazing photos and bragging rights that you took them for the low, low price of a really big helium balloon and a fill.

But what if you shrunk everything down? Over the last few years, [Andy, VK3YT] has been launching ever smaller and lighter balloons with very low power ham radio payloads. So no camera and no photos, but the payback is that he’s launching payloads that weigh around thirteen grams complete with GPS, radio, solar cell, and batteries. They can stay up for weeks and go really far. We’d love to see some construction details beyond the minimalistic “Solar powered party balloon, 25mW TX”. But that about sums it up.

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Retro-fit Old Radio With Arduino And FM Module

July 2, 2015 by 30 Comments

“You can’t put new wine in old bottles” – so the saying goes. But you would if you’re a hacker stuck with a radio built in 2005, which looked like it was put together using technology from 1975. [Marcus Jenkins] did just that, pulling out the innards from his old radio and converting it to an Arduino FM radio.

His cheap, mains powered radio was pretty bad at tuning. It had trouble locating stations, and tended to drift. One look at the insides, and it was obvious that it was not well engineered at all, so any attempts at fixing it would be pointless. Instead, he drew up a simple schematic that used an Arduino Nano, an FM radio module based on the TEA5767, and an audio amplifier based on the LM386.

A single button on the Arduino helps cycle through a range of preset frequencies stored in memory. The Arduino connects to the FM radio module over I2C. The existing antenna was connected to the TEA5767 module. The radio module outputs stereo audio, but [Marcus] was content with using just a mono channel, as it would be used in his workshop. The audio amplifier is pretty straightforward, based on a typical application found in the data sheet. He put it all together on proto-board, although soldering the FM radio module was a bit tricky. The Arduino code is quite simple, and available for download (zip file).

He retained the original tuning knob, which is no longer functional. The AM-FM selector knob was fitted with a micro-switch connected to the Arduino for selecting the preset stations. Almost everything inside was held together with what [Marcus] calls “hot-snot” glue. The whole exercise cost him a few Euros, and parts scavenged from his parts bin. A good radio could probably be had for a few Euros from a yard sale and much less effort, but that wouldn’t be as cool as this.

Go deeper and explore how FM signals are modulated and demodulated for playback.

RF scanner

Easy Way To Listen To Cube Sats

June 29, 2015 by 15 Comments

[Bill Meara] has discovered an easy way to listen to amateur “cube-sat” satellites using a cheap SDR Dongle.

The DVB-T SDR Dongle comes in at a whopping thirteen bucks, and the highly sophisticated antenna (pdf) is made from a bit of copper wire and uses aluminum wire for the ground plane.

Once he had everything hooked up, [Bill] went to the Heavens Above website to see when satellites would be passing over him. He was able to lock onto the Prism Satellite, and then a couple other cube-sats that were launched from Russia and Istanbul.

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The Alexanderson Transmitter: Very-low Frequency Radio Rides Again!

June 27, 2015 by 44 Comments

Is your ham radio rig made of iron and steel? Is it mechanically driven? Classified as a World Heritage Site? We didn’t think so. But if you’d like to tune in one that is, or if you’re just a ham radio geek in need of a bizarre challenge, don’t miss Alexanderson Day 2015 tomorrow, Sunday, June 28th

The Alexanderson Transmitter design dates back to around 1910, before any of the newfangled tube technology had been invented. Weighing in at around 50 tons, the monster powering the Varberg Radio Station is essentially a high-speed alternator — a generator that puts out 17.2 kHz instead of the 50-60 Hz  that the electric companies give us today.

Most of the challenge in receiving the Alexanderson transmitter broadcasts are due to this very low broadcast frequency; your antenna is not long enough. If you’re in Europe, it’s a lot easier because the station, SAQ, is located in Sweden. But given that the original purpose of these behemoths was transcontinental Morse code transmission, it only seems sporting to try to pick it up in the USA. East Coasters are well situated to give it a shot.

And of course, there’s an app for that. The original SAQrx VLF Receiver and the extended version both use your computer’s sound card and FFTs to extract the probably weak signal from the noise.

We scouted around the net for an antenna design and didn’t come up with anything more concrete than “few hundred turns of wire in a coil” plugged into the mic input.  If anyone has an optimized antenna design for this frequency, post up in the comments?

Thanks [Martin] for the tip!

Building Your Own SDR-based Passive Radar On A Shoestring

June 5, 2015 by 82 Comments

Let’s start off with proof. Below is an animation of a measurement of airplanes and meteors I made using a radar system that I built with a few simple easily available pieces of hardware: two $8 RTL software defined radio dongles that I bought on eBay, and two log-periodic antennas. And get this, the radar system you’re going to build works by listening for existing transmissions that bounce off the targets being measured!

I wrote about this in a very brief blog posting a few years ago. It was mainly intended as a zany little side story for our radio telescope blog, but it ended up raising a lot of interest. Because this has been a topic that keeps attracting inquiries, I’m going to explain how I did the experiment in more detail.

It will take a few posts to show how to build a radar capable of performing these types of measurements. This first part is the overview. In later postings I will go through more detailed block diagrams of the different parts of a passive radar system, provide example data, and give some Python scripts that can be used to perform passive radar signal processing. I’ll also go through strategies to determine that everything is working as expected. All of this may sound like a lot of effort, but don’t worry, making a passive radar isn’t too complicated.

Let’s get started!

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