Hams in Space: Project OSCAR

In early December 1961, a United States Air Force rocket took off from Vandenberg Air Force Base in California carrying a special payload. The main payload was a Corona surveillance satellite, but tucked just aft of that spacecraft was a tiny package of homebrew electronics stuffed into something the looked like a slice of cake. What was in that package and how it came to tag along on a top-secret military mission is the story of OSCAR 1, the world’s first amateur radio satellite.

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Hacking When It Counts: The Great Depression

In the summer of 1929, it would probably have been hard for the average Joe to imagine the degree to which his life was about to change. In October of that year, the US stock market tumbled, which in concert with myriad economic factors kicked off the Great Depression, a worldwide economic disaster that would send ripples through history to this very day. At its heart, the Depression was about a loss of confidence, manifested in bank failures, foreclosures, unemployment, and extreme austerity. People were thrust into situations for which they were ill-prepared, and if they were going to survive, they needed to adapt and do what they could with what they had on hand. In short, they needed to hack their way out of the Depression.

Social Hacking: Welcome to the Jungle

Hobos2
Bindlestiffs ambulating down the high iron. Source: Wikipedia

One reaction to the change in the social contract in the 1930s was increased vagrancy. While homelessness was certainly thrust upon some people by circumstances – in the depth of the Depression in 1933, something like 25% of men were unemployed, after all – life on the road was clearly a choice for millions. A typical story was that of the bored teenage boy, facing no prospects for a job and wishing to relieve his large family of the burden of one more mouth to feed. Hitting the road with a few possessions in his “bindle,” he learned the craft of life on the road from more experienced vagrants. And thus another hobo was created.

The popular image of the hobos as unique to the Depression is a little awry. Economic upheaval certainly swelled their ranks, but in America, hobos had first appeared after the Civil War, with war-weary veterans riding the rails looking for work. By the time the Depression hit, there was an extensive hobo culture in the United States, complete with its own slang and a rough code of ethics.

Hobos were top of the heap in the vagrant hierarchy, the “knights of the road.” They were migrant workers, generally unskilled, willing to stay in one place for a paying job but unwilling to commit to settling down. When the job was done or he had made enough money, he moved on. Tramps were the next step down – wanderers who were willing to work but only when absolutely necessary. Lowest in the pecking order were the bums who stayed put and relied on the kindness of strangers for their survival. Regardless of rank, all the vagrants had one thing in common – the road. More or less constantly on the move, they had to quickly learn how to provide for themselves without the creature comforts, which before the Depression hit had begun to include many modern conveniences.

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Hobo stove in action. Source: Log Cabin Cooking

Cooking arrangements were one thing hobos excelled at, whether on the road or in one of the many hobo camps, or jungles, that sprung up at railroad crossings outside of towns. A campfire in a ring of rocks is the traditional view of outdoor cookery, but the hobos quickly learned that it’s not terribly fuel-efficient. One solution to this problem was the hobo stove, an ancestor of the rocket stove. Relying on convection to draw a huge volume of air into a combustion chamber, hobo stoves were easily fabricated from tin cans and other metal scraps that were easy to come by in a world before recycling and large municipal landfills. Most were assembled on the spot and served for a meal or two before being abandoned, but some actually had insulation between double walls and clever arrangements of the fuel shelf to feed automatically as the fuel burned away. Scraps of wood, pinecones, newspapers and cardboard – a hobo stove will eat almost anything, and burn hot enough that even damp fuel isn’t a problem.

Often finding himself with time on his hands, many a hobo kept himself busy with arts and crafts projects in camp. Making hobo nickels was a popular way to pass the time, and often resulted in a trade item far more valuable than the base value of the starting material. The Indian head figure on the US Buffalo nickels of the day were modified with tools fabricated from old nails and files; metal was pushed around the coin to create features on the figure, usually a bowler hat and facial hair. A ‘bo could trade the miniature bas-relief sculpture for a good meal; today genuine hobo nickels from the Depression era command high prices from collectors.

Radio: Razor Blades and Copper Pipe

Unless the hobo was flopping in town or at a really well-equipped jungle, chances are pretty good he wasn’t listening to the radio too much. From our 21st century outlook, it’s sometimes hard to appreciate how new and exciting radio was and the impact it had on everyday life in America during the Depression. Radio connected the nation in a way no other medium ever had. That the Depression did not kill this infant technology in its cradle is a testament to both its power as a medium – families would stop making payments on almost everything else so they could keep their radio sets – and to the tenacity of early electronics hobbyists, who learned to keep radios alive and even to fabricate them from almost nothing.

CrystalRadio
CrystalRadio” by JA.Davidson

Although tube-type superheterodyne receivers were widely available all through the Depression, crystal sets were still a popular and sometimes necessary hacker project during the Depression. Relying on nothing more than a tuned circuit and a detector connected to an antenna and high-impedance headphones, a crystal set was able to pick up strong AM broadcasts and sometimes even shortwave stations. The earliest detectors were crystals of galena probed by a tiny “cat’s whisker” wire, but metal oxides could also form the necessary rectifying junction, leading to detectors built out of razor blades and safety pins. Crystal radio skills would serve many a Depression-era farm boy well during the next decade as they went off to war in Europe and the Pacific; there they created foxhole radios to listen in on broadcasts without the risk of a more sophisticated radio set, whose local oscillator could be detected by the enemy.

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VE7SL’s replica 1929 TNT transmitter, a close relative of the Hartley. Source: The VE7SL Radio Notebook

Receivers weren’t the only area in which Depression-era hackers made an impact. As commercial broadcasting took off, so did amateur radio, and few commercial transmitters were available to satisfy the burgeoning ham market. Depression-era hams had to home-brew almost everything and came up with some beautiful designs that modern glowbug hams recreate with loving attention to detail. A popular transmitter back in the day was based on the Hartley oscillator (PDF link). Using only a single triode tube and a tuned circuit with coils wound from 1/4″ copper tubing, Hartley transmitters could be built on a literal breadboard from scraps and widely available parts. Tuned to the 40- or 80-meter band, or even down to the 160-meter band, a Hartley or the closely related Tuned-Not-Tuned (TNT) or Tune-Plate-Tuned-Grid (TPTG) continuous-wave (CW) transmitters could put out enough power to work coast-to-coast contacts, or QSOs. Modern hams pay homage to the Depression-era pioneers of amateur radio with regular “QSO Parties” using replica Hartleys – most with bypass capacitors to keep the lethal voltages their forebears had to deal with off the coils.

The Great Depression lasted through the 1930s in America, finally dissipating just before the country mobilized for World War II. With factories suddenly working beyond capacity to supply the war effort, unemployment figures quickly plummeted, and the austere practices of the Depression were generally rolled back. Hobo culture declined and amateur radio was shut down by the federal government for the duration of the war, but neither the war effort nor full employment could kill the hobo spirit — modern hobos still ply the rails to this day. And the skills and mindsets developed by Depression-era social and electronics hackers paved the way for a lot of what was to come in the post-war years.

Get Your Amateur Radio License Already!

We run a lot of posts on amateur radio here at Hackaday, and a majority of our writers and editors* are licensed hams. Why? Because playing around with radio electronics is fun, and because having a license makes a lot more experimentation legal. (*We’re sure you have good reasons for slacking, Szczys.)

So let’s say that you want to get your “ticket” (and you live in the USA). It’s easy: just study for an exam or two, and take them. How to study? We’re glad you asked, because we just found this incredibly long video that’ll prep you for the exam.

swr_powerAt six and a half hours, we’ll admit that we haven’t watched the whole thing, but what we did see looks great. Admittedly, we were a little bit unnerved by [John (KD65CY)]’s overdone enthusiasm. But the content is fundamental, broad-ranging, and relevant. Heck, even a bit entertaining.

Even if you’re not interested in taking the exam, but are just interested in some radio basics, it’s worth looking. If you give it a shot, and like what you see, let us know in the comments what times stamps you found interesting.

The other “secret” about the amateur radio exams is that all of the questions and their answers are drawn from a publicly available pool of questions. This means that you can just cram the right answers, pass the exam, and you’ll have your grey cells back good as new in no time. To help you along your path, here are all the current Technician questions with only the correct answer for each. (And here is the Python script that generated them.) Read through this, take a couple of practice exams, and you’ll be ready to go.

In our experience, the Technician exam is easy enough that it’s probably worth your while to study up for the General exam as well. You have to take the former before the latter, but there’s nothing stopping you from taking them all in one sitting. (General gets you a lot more international shortwave frequencies, so it’s at least worth a shot.)

But don’t let that slow you down. Just getting the Tech license is easily worth studying up for a couple of hours or so. You have no excuses now. Go do it!

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Transmitting Tee Vee From A Pi

Want to set up your own television station? This hack might help: [Jan Panteltje] has worked out how to turn a Raspberry Pi into a DVB-S transmitter. DVB-S is a TV transmission standard originally created for satellite broadcasts, but Hams also use it to send video on the amateur bands. What [Jan] did was to use software on the Pi to encode the video into the transport stream, which is then fed out to the home-made transmitter that modulates the data into a DVB-S signal. [Jan] has successfully tested the system with a direct connection, feeding the output of the transmitter into a DVB-S decoder card that could read the data and decode the video signal. To create a real broadcast signal, the next step would be to feed the output of the signal into an amplifier and larger transmitter that broadcast the signal.

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APRS Repeaters Get the Signal Out of Mammoth Cave

APRS Cave-Link uses the amateur radio’s Automatic Packet Reporting System (APRS) inside caves to get their position data (and other messages) out.

Imagine that you’re coordinating a large scale search-and-rescue mission in a cave. You need to know where all your groups are, and whether or not they’ve found anything. But how do they all communicate to the command center?

You’d guess radio, but you’d guess wrong. Radio doesn’t propagate well at all in a maze of twisty passages, all alike; rocks absorb radio waves, especially in the VHF/UHF range that’s best suited for most small radios. In the past, you’d run wire and transmit along it. This article runs through the options in detail. But adding miles of wire to your already heavy caving and climbing gear is a nuisance or worse.

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RPiTX Turns Rasberry Pi into Versatile Radio Transmitter

Since the discovery that some USB TV tuner dongles could be used to monitor radio waves across a huge amount of spectrum, the software-defined radio world has exploded with interest. The one limiting factor, though, has been that the dongles can only receive signals; they can’t transmit them. [Evariste Okcestbon, F5OEO] (if that is his real name! Ok c’est bon = Ok this is good) has written some software that will get you transmitting using SDR with only a Raspberry Pi and a wire.

There have been projects in the past that use a Pi to broadcast radio (PiFM), but this new software (RPiTX) takes it a couple steps further. Using just an appropriately-sized wire connected to one of the GPIO pins, the Raspberry Pi is capable of broadcasting using FM, AM, SSB, SSTV, or FSQ signals. This greatly increases the potential of this simple computer-turned-transmitter and anyone should be able to get a lot of use out of it. In the video demo below the break, [Evariste] records a wireless doorbell signal and then re-transmits it using just the Rasbperry Pi.

The RPiTX code is available on GitHub if you want to try it out. And it should go without saying that you will most likely need an amateur radio license of some sort to use most of these features, depending on your locale. If you don’t have a ham radio license yet, you don’t need one to listen if you want to get started in the world of SDR. But a ham license isn’t hard to get and at this point it shouldn’t take much convincing for you to get transmitting.

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Tiny Radio Tracks Your Balloons

The name of the game in rocketry or ballooning is weight. The amount of mass that can be removed from one of these high-altitude devices directly impacts how high and how far it can go. Even NASA, which estimates about $10,000 per pound for low-earth orbit, has huge incentives to make lightweight components. And, while the Santa Barbara Hackerspace won’t be getting quite that much altitude, their APRS-enabled balloon/rocket tracker certainly helps cut down on weight.

Tracksoar is a 2″ x .75″ x .5″ board which weighs in at 45 grams with a pair of AA batteries and boasts an ATmega 328P microcontroller with plenty of processing power for its array of on-board sensors. Not to mention everything else you would need like digital I/O, a GPS module, and, of course, the APRS radio which allows it to send data over amateur radio frequencies. The key to all of this is that the APRS module is integrated with the board itself, which saves weight over the conventional method of having a separate APRS module in addition to the microcontroller and sensors.

As far as we can see, this is one of the smallest APRS modules we’ve ever seen. It could certainly be useful for anyone trying to save weight in any high-altitude project. There are a few other APRS projects out there as well but remember: an amateur radio license will almost certainly be required to use any of these.