Radio Hacks

1403 Articles

Sage Advice For The New Ham

March 5, 2016 by 39 Comments

If you’re on the edge about getting your amateur radio license, just go do it and worry about the details later. But once you’ve done that, you’re going to need to know a little bit about the established culture and practices of the modern ham — the details.

Toward that end, [McSteve] has written up a (so far) two-part introductory series about ham radio. His first article is fairly general, and lays out many of the traditional applications of ham radio: chatting with other humans using the old-fashioned analog modes. You know, radio stuff.

The second article focuses more on using repeaters. Repeaters can be a confusing topic for new radio operators: there are two frequencies — one for transmitting and one for receiving — and funny control tones (CTCSS) etc. This article is particularly useful for the new ham, because you’re likely to have a relatively low powered radio that would gain the most from using a repeater, and because the technology and traditions of repeater usage are a bit arcane.

So if you’re thinking about getting your license, do it already. And then read through these two pages and you’re good to go. We can’t wait to see what [McSteve] writes up next.

Serial Telemetry To Wi-Fi With An ESP8266

March 4, 2016 by 12 Comments

Hackaday.io user [J. M. Hopkins] had a problem with his rocketry. Telemetry from the rockets came down to Earth via a 433MHz serial link, but picking just the bits he needed from a sea of data for later analysis on a laptop screen on bright sunny days was getting a little difficult.

His solution was to bring the serial data from his transceiver module to an ESP8266, and from that both share it over WiFi and display pertinent information via I2C to an LCD for easy reference. And he’s put the whole lot with a power supply in a rather splendid wooden case with an SMA socket on the back to attach his Yagi.

All information received from the telemetry is passed to a client connecting via Telnet over the WiFi, but pertinent information for the LCD is selected by sending it from the rocket enclosed in square brackets. We hope that the source code will be forthcoming in time.

This isn’t the first time we’ve featured rocket telemetry here at Hackaday. And we’d be missing a trick if we didn’t point out that this project is using our own Hackaday-branded Huzzah ESP8266 breakout board from the Hackaday Store.

Swarm Of Tiny Pirate Transmitters Gets The Message Out In Syria

March 3, 2016 by 76 Comments

They say that the first casualty of war is the truth, and that’s probably only more the case in a civil war. When one side in a conflict controls the message, the other side is at a huge disadvantage. Technology can level the playing field, and in the case of the Syrian Civil War, a swarm of tiny Raspberry Pi transmitters is helping one side get their message out.

We won’t pretend to understand the complexities of this war, but it’s clear that the Syrian government controls broadcast media and access to the internet, and is using them for propaganda while denying the opposition access to the same. A decentralized medium can get the message out under these conditions, and that’s exactly what Pocket FM does. Built around a Raspberry Pi and a frequency-agile FM transmitter, a Pocket FM can take multiple audio feeds and transmit them out to a 5km radius. Small enough to be packed up and deployed quickly and able to be powered by batteries or solar panels, the pirate transmitters can be here one minute and gone the next, yielding a robust network resistant to takedown attempts.

The network built around Pocket FM in Syria is small but growing, and it appears to be making a difference in the conflict. We find the concept of a decentralized network intriguing and potentially empowering, at least in situations where the letter of the law regarding broadcasting is not a prime consideration. That’s where projects like Airchat seek to build an unsanctioned network. The same goes for Tweeting on the Amateur Radio Band in a project aptly named HamRadioTweets.

We wonder how a fleet of these Pi-based transmitters could aid in recovery from natural disasters?

[via r/amateurradio and TomHiggins]

Google Is Building A 100kW Radio Transmitter At A Spaceport And No One Knows Why

March 2, 2016 by 154 Comments

You can find the funniest things in public government documents. There’s always ample evidence your local congress critter is working against the interests of their constituency, nation, and industry controlled by the commission they’re chairperson of. Rarely, though, do you find something surprising, and rarer still does it portend some sort of experiments conducted by Google at a spaceport in New Mexico.

In a publication released last week, Google asked the FCC to treat some information relating to radio experiments as confidential. These experiments involve highly directional and therefore high power transmissions at 2.5 GHz, 5.8GHz, 24GHz, 71-76GHz, and 81-86GHz. These experiments will take place at Spaceport America, a 12,000 foot runway in the middle of New Mexico occasionally used by SpaceX, Virgin Galactic, and now Google.

For the most part, this document only tells the FCC that Google won’t be causing harmful interference in their radio experiments. There few other details, save for what bands and transmitters Google will be using and an experimental radio license call sign (WI9XZE) that doesn’t show up in the FCC database.

Of the few details listed in the documents, one thing does pop out as exceptionally odd: a 70-80 GHz transmitter with an effective radiated power (ERP) 96,411 W. That’s close enough to 100 kilowatts to call it as such. This is the maximum effective radiated power of the highest power FM stations in the US, but radio stations are omnidirectional, whereas Google is using very high gain antennas with a beam width of less than half a degree. The actual power output of this transmitter is a mere half watt.

The best guess for what Google is doing out in the New Mexico desert is Project Skybender, a project to use millimeter waves to bring faster Internet to everyone. There aren’t many details, but there is a lot of speculation ranging from application in low Earth orbit to something with Google Loon.

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?
Continue reading “Do You Know Rufus Turner?” →

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