Radio Hacks

1315 Articles

Sputnik’s Transmitter Beeps Again

February 23, 2016 by 36 Comments

Sputnik. The first artificial satellite, the launch of which precipitated the space race. Without the frenetic pace of technological advancement as the USA and the USSR vied with each other during the decade following its launch it is safe to say that we might not yet have many of the tools and components we take for granted as electronics enthusiasts and makers today.

[Frank Waarsenburg PA3CNO] has taken on the interesting task of recreating one of the Sputnik radio transmitters using a set of the original Russian tubes.

Sputnik itself was an astounding achievement for the team of engineers and scientists who put it into orbit, but the drive to beat the USA to the post within the 1957 International Geophysical Year meant that it was a surprisingly simple device. A sphere pressurised with nitrogen and with those iconic whip antennas mounted on its outside, containing a battery, 20 and 40 MHz tube radio transmitters, and a fan cooling system. Its design was a Soviet state secret, but in 2013 [Oleg, RV3GM] located the schematic used for the transmitter.

The tubes are slightly unusual, being a wire-ended design with all electrodes mounted on rods the length of the glass envelope. This design feature gave them a resistance to acceleration and vibration, making them suitable for use in aircraft, missiles, and rockets.

[Frank] faced one or two hurdles during his construction, including the development of a suitable power supply and finding an unfortunate bug in the Russian schematic. If you speak Dutch or are prepared to use a translation tool his full write-up can be found in the Dutch-language RAZzies magazine, December issue featuring the power supply (PDF, Dutch), and January issue featuring the transmitter (PDF, Dutch).

The Sputnik satellite has not appeared on its own in these pages before, but we have recently featured the early OSCAR amateur radio satellites and the revival of a piece of space-race-era Soviet rocket technology.

Via [Stefan, HB9TWS], whose English-language coverage of the transmitter was of great help.

Do You Know Rufus Turner?

February 15, 2016 by 45 Comments

It is hard to be remembered in the electronics business. Edison gets a lot of credit, as does Westinghouse and Tesla. In the radio era, many people know Marconi and de Forest (although fewer remember them every year), but less know about Armstrong or Maxwell. In the solid-state age, we tend to remember people like Shockley (even though there were others) and maybe Esaki.

If you knew most or all of those names without looking them up, you are up on your electronics history. But do you know the name Rufus Turner?
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A Geek’s Revenge For Loud Neighbors

February 5, 2016 by 124 Comments

It seems [Kevin] has particularly bad luck with neighbors. His first apartment had upstairs neighbors who were apparently a dance troupe specializing in tap. His second apartment was a town house, which had a TV mounted on the opposite wall blaring American Idol with someone singing along very loudly. The people next to [Kevin]’s third apartment liked music, usually with a lot of bass, and frequently at seven in the morning. This happened every day until [Kevin] found a solution (Patreon, but only people who have adblock disabled may complain).

In a hangover-induced rage that began with thumping bass at 7AM on a Sunday, [Kevin] tore through his box of electronic scrap for every capacitor and inductor in his collection. An EMP was the only way to find any amount of peace in his life, and the electronics in his own apartment would be sacrificed for the greater good. In his fury, [Kevin] saw a Yaesu handheld radio sitting on his desk. Maybe, just maybe, if he pressed the transmit button on the right frequency, the speakers would click. The results turned out even better than expected.

With a car mount antenna pointed directly at the neighbor’s stereo, [Kevin] could transmit on a specific, obscure frequency and silence the speakers. How? At seven in the morning on a Sunday, you don’t ask questions. That’s a matter for when you tell everyone on the Internet.

Needless to say, using a radio to kill your neighbor’s electronics is illegal, and it might be a good idea for [Kevin] to take any references to this escapade off of the Internet. It would be an even better idea to not put his call sign online in the future.

That said, this is a wonderful tale of revenge. It’s not an uncommon occurrence, either. Wikihow, Yahoo Answers and Quora – the web pages ‘normies’ use for the questions troubling their soul – are sometimes unbelievably literate when it comes to unintentional electromagnetic interference, and some of the answers correctly point out grounding a stereo and putting a few ferrite beads on the speaker cables is the way to go. Getting this answer relies entirely on asking the right question, something I suspect 90% of the population is completely incapable of doing.

While [Kevin]’s tale is a grin-inducing two-minute read, You shouldn’t, under any circumstances, do anything like this. Polluting the airwaves is much worse than polluting your neighbor’s eardrums; one of them violates municipal noise codes and another is breaking federal law. It’s a good story, but don’t do it yourself.

Editor’s Note: Soon after publishing our article [Kevin] took down his post and sent us an email. He realized that what he had done wasn’t a good idea. People make mistakes and sometimes do things without thinking. But talking about why this was a bad idea is one way to help educate more people about responsible behavior. Knowing you shouldn’t do something even though you know how is one paving stone on the path to wisdom.
–Mike Szczys

Hacking The Internet Of Things: Decoding LoRa

January 31, 2016 by 20 Comments

Getting software-defined radio (SDR) tools into the hands of the community has been great for the development and decoding of previously-cryptic, if not encrypted, radio signals the world over. As soon as there’s a new protocol or modulation method, it’s in everyone’s sights. A lot of people have been working on LoRa, and [bertrik] at RevSpace in The Hague has done some work of his own, and put together an amazing summary of the state of the art.

LoRa is a new(ish) modulation scheme for low-power radios. It’s patented, so there’s some information about it available. But it’s also proprietary, meaning that you need a license to produce a radio that uses the encoding. In keeping with today’s buzzwords, LoRa is marketed as a wide area network for the internet of things. HopeRF makes a LoRa module that’s fairly affordable, and naturally [bertrik] has already written an Arduino library for using it.

So with a LoRa radio in hand, and a $15 RTL-SDR dongle connected to a laptop, [bertrik] got some captures, converted the FM-modulated chirps down to audio, and did a bunch of hand analysis. He confirmed that an existing plugins for sdrangelove did (mostly) what they should, and he wrote it all up, complete with a fantastic set of links.

There’s more work to be done, so if you’re interested in hacking on LoRa, or just having a look under the hood of this new modulation scheme, you’ve now got a great starting place.

The Michigan Mighty-Mite Rides Again

January 29, 2016 by 12 Comments

One of the best things about having your amateur radio license is that it allows you to legally build and operate transmitters. If you want to build a full-featured single-sideband rig with digital modes, have at it. But there’s a lot of fun to be had and a lot to learn from minimalist builds like this Michigan Mighty-Mite one-transistor 80-meter band transmitter.

If the MMM moniker sounds familiar, it may be because of this recent post. And in fact, [W2AEW]’s build was inspired by the same SolderSmoke blog posts that started [Paul Hodges] on the road to his breadboard and beer can build.  [W2AEW]’s build is a bit sleeker, to be sure, but where the video really shines is in the exploration and improvement of the signal quality. The basic Mighty-Mite outputs a pretty dirty signal – [W2AEW]’s scope revealed 5 major harmonic spikes, and what was supposed to be a nice sine wave was full of divots and potholes. There’s only so much one transistor, a colorburst crystal and a couple of capacitors can do, so the video treats us to an explanation of the design of the low-pass filter needed to get rid of the harmonics and clean up the output into a nice solid sine wave.

If your Morse skills aren’t where they should be to take advantage of the Might-Mite’s CW-only mode, then you’ll need to look at other modulations. Maybe a tiny FM transmitter would suit your needs better?

Continue reading “The Michigan Mighty-Mite Rides Again” →

Whiskey Tango Foxtrot Is The Phonetic Alphabet?

January 26, 2016 by 98 Comments

Sometimes words just have to be spelled for others. I’ve been on phone conversations where the person on the other end is spelling for me and it’s painful. “Was that a ‘b’ or a ‘p’?” Sometimes they’ll try on the fly to use words with the beginning letter trying to convey the letter: “B as in boy”. Then they’ll get stumped mumbling while they think desperately for ‘k’ words… ‘ketchup’. Okay, but is that really ketchup or catsup? Now think how much easier spelling is on a phone than over a poor quality radio channel. What we say, and how we say it is the key to our brain’s ability to error correct human speech. It’s a solved problem that was built into radio etiquette long ago.

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35 Million People Didn’t Notice When Zynq Took Over Their Radio

January 23, 2016 by 39 Comments

What happens when part of a radio transmitting service listened to by over half the country needs to be replaced? That was a recent challenge for the BBC’s Research and Development team last year, and if you’re from the UK — you wouldn’t have noticed a single thing.

[Justin Mitchell] is a principle engineer in R&D at BBC, and just this past year had to transition the audio coding system installed in 1983 to new hardware due to failing circuit boards and obsolete components. The encoding is used to get audio from a central source to broadcasting towers all over the country. The team had to design and build a replacement module that would essentially replace an entire server rack of ancient hardware — and make it plug-and-play. Easy, right? Continue reading “35 Million People Didn’t Notice When Zynq Took Over Their Radio” →