Radio Hacks

1394 Articles

Anatomy Of A Digital Broadcast Radio System

January 9, 2017 by 33 Comments

What does a Hackaday writer do when a couple of days after Christmas she’s having a beer or two with a long-term friend from her university days who’s made a career in the technical side of digital broadcasting? Pick his brains about the transmission scheme and write it all down of course, for behind the consumer’s shiny digital radio lies a wealth of interesting technology to try to squeeze the most from the available resources.

In the UK, our digital broadcast radio uses a system called DAB, for Digital Audio Broadcasting. There are a variety of standards used around the world for digital radio, and it’s fair to say that DAB as one of the older ones is not necessarily the best in today’s marketplace. This aside there is still a lot to be learned from its transmission scheme, and from how some of its shortcomings were addressed in later standards. Continue reading “Anatomy Of A Digital Broadcast Radio System” →

Did A Russian Physicist Invent Radio?

January 9, 2017 by 122 Comments

It is said that “success has many fathers, but failure is an orphan.” Given the world-changing success of radio in the late 19th and early 20th centuries, it’s no wonder that so many scientists, physicists, and engineers have been credited with its invention. The fact that electromagnetic radiation is a natural phenomenon that no one can reasonably claim to have invented sometimes seems lost in the shuffle to claim the prize.

But it was exactly through the study of natural phenomena that one of the earliest pioneers in radio research came to have a reasonable claim to at least be the inventor of the radio receiver, well before anyone had learned how to reliably produce electromagnetic waves. This is the story of how a Russian physicist harnessed the power of lightning and became one of the many fathers of radio.

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The Poynting Vector Antenna

January 6, 2017 by 45 Comments

Radio amateurs are inventive people, and though not all of them choose to follow it there is a healthy culture of buildng radio equipment among them. In particular the field of antennas is where you’ll find a lot of their work, because the barrier to entry can be as low as the cost of a reel of wire.

Over the years a number of innovative antenna designs have come from radio amateurs’ experimentation, and it’s one of the more recent we’d like to share with you today following a [Southgate ARC] story about a book describing its theory (Here’s an Amazon link to the book itself). The Poynting Vector antenna has been one of those novel designs on the fringes for a while now, it has been variously described as the “Super-T”, or the “flute”. Its party piece is tiny dimensions, a fraction of the size of a conventional dipole, and it achieves that by the interaction between a magnetic field across the plates of a capacitor in a tuned circuit and the electric field between a very short pair of dipole radiators. The trade-off is that it has an extremely high Q and thus a narrow bandwidth, and since its feeder can become part of its resonant circuit it is notoriously difficult to match to a transmitter. [Alan MacDonald, VE3TET] and [Paul Birke, VE3PVB] have a detailed page on the development of their Poynting antenna which takes the reader through the details of its theory and the development of their practical version.

In the roof space above the room in which this is being written there hangs a traditional dipole for the 20m amateur band. Though it is a very effective antenna given that it is made from a couple of pieces of wire and a ferrite core it takes most of the length of the space, and as we’re sure Hackaday readers with callsigns will agree a relatively tiny alternative is always very welcome.

If antennas are a mystery to you then we’d suggest you read an introduction to antenna basics to get you started.

Visualization Of A Phased Array Antenna System

January 5, 2017 by 39 Comments

Phased array antenna systems are at the cusp of ubiquity. We now see Multiple-Input Multiple-Output (MIMO) antenna systems on WiFi routers. Soon phased array weather radar systems will help to predict the weather and keep air travel safe, and phased array base stations will be the backbone of 5G which is the next generation of wireless data communication.  But what is a phased array antenna system?  How do they work?  With the help of 1024 LEDs we’ll show you.

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Junkyard Dish Mount Tracks Weather Satellites

January 2, 2017 by 11 Comments

There’s a magnificent constellation of spacecraft in orbit around Earth right now, many sending useful data back down to the surface in the clear, ready to be exploited. Trouble is, it often takes specialized equipment that can be a real budget buster. But with a well-stocked scrap bin, a few strategic eBay purchases, and a little elbow grease, a powered azimuth-elevation satellite dish mount can become affordable.

The satellites of interest for [devnulling]’s efforts are NOAA’s Polar-orbiting Operational Environmental Satellites (POES), a system of low-Earth orbit weather birds. [devnulling] is particularly interested in direct reception of high-definition images from the satellites’ L-band downlink. The mount he came up with to track satellites during lengthy downloads is a tour de force of junkyard build skills.

The azimuth axis rotates on a rear wheel bearing from a Chevy, the elevation axis uses cheap pillow blocks, and the frame is welded from scrap angle iron and tubing. A NEMA-23 stepper with 15:1 gearhead rotates the azimuth while a 36″ linear actuator takes care of elevation. The mount has yet to be tested in the wind; we worry that sail area presented by the dish might cause problems. Here’s hoping the mount is as stout as it seems, and we’ll look forward to a follow-up.

It would work for us, but a 4-foot dish slewing around in the back yard might not be everyone’s taste in lawn appurtenances. If that’s you and you still want to get your weather data right from the source, try using an SDR dongle and chunk of wire.

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Listen To The Globe

January 2, 2017 by 19 Comments

There was a time when electronic hackers (or hobbyist, enthusiasts, geeks, or whatever you want to be called) were better than average at geography. Probably because most of us listened to shortwave radio or even transmitted with ham radio gear. These days, if you try listening to shortwave, you have to be pretty patient. Unless you want to hear religious broadcasters or programming aimed at the third world, there’s not much broadcast traffic to listen to anymore

The reason, of course, is the Internet. But we’ve often thought that it isn’t quite the same. When you tuned in London on your homebrew regenerative receiver, you wanted to know where that voice was coming from, and you couldn’t help but learn more about the area and the people who live there. Tune into a BBC live stream on the Internet, and it might as well be any other stream or podcast from anywhere in the world.

The New Shortwave

Maybe we need to turn kids on to Radio Garden. Superficially, it isn’t a big deal. Another catalog of streaming radio stations. You can find plenty of those around. But Radio Garden has an amazing interface (and a few other unique features). That interface is a globe. You can see dots everywhere there’s a broadcast station and with a click, you are listening to that station. The static and tuning noises are a nice touch.

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Run Your Own Numbers Station

December 31, 2016 by 26 Comments

Numbers stations are shortwave stations that broadcast cryptic messages that are widely assumed to be used for communications between nation states and spies. But who’s to say it’s up to the government to have all the fun? If you’ve always dreamed of running your own spy ring, you’ll need a way to talk to them too. Start with this guide on how to run your own numbers station.

The requirements are simple – you just need random numbers, one time pads for each recipient (available from our store!) and a way to send the audio – ideally a powerful shortwave transmitter, but for an intelligence agency on a budget, online streaming will work. Then you’re ready to send your message. [Jake Zielke] shares techniques on how to easily encode a message into numbers for transmission, and how to encrypt them with one time pad techniques. Done properly, this is an unbreakable form of encryption. [Jake] then rounds out the guide with tips on how to format your station’s transmissions to address multiple secret agents effectively.

It’s a great way to get started in the world of spooky secret radio communications. All the tools needed to get started are available on the page, so you’ll be up and running in no time. Meanwhile, why not do a little more research on the history of numbers stations?