ham radio

232 Articles

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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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!

APRS Tracking System Flies Your Balloons

March 24, 2015 by 27 Comments

Looking for a way to track your high-altitude balloons but don’t want to mess with sending data over a cellular network? [Zack Clobes] and the others at Project Traveler may have just the thing for you: a position-reporting board that uses the Automatic Packet Reporting System (APRS) network to report location data and easily fits on an Arduino in the form of a shield.

The project is based on an Atmel 328P and all it needs to report position data is a small antenna and a battery. For those unfamiliar with APRS, it uses amateur radio frequencies to send data packets instead of something like the GSM network. APRS is very robust, and devices that use it can send GPS information as well as text messages, emails, weather reports, radio telemetry data, and radio direction finding information in case GPS is not available.

If this location reporting ability isn’t enough for you, the project can function as a shield as well, which means that more data lines are available for other things like monitoring sensors and driving servos. All in a small, lightweight package that doesn’t rely on a cell network. All of the schematics and other information are available on the project site if you want to give this a shot, but if you DO need the cell network, this may be more your style. Be sure to check out the video after the break, too!

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PortableSDR Needs A Cinderella Story To Finish Its Kickstarter

February 9, 2015 by 37 Comments

If you haven’t backed PortableSDR on Kickstarter, now’s the time to do it. [Michael Colton’s] project which frees a Software Defined Radio from being shackled to a computer is in the final three days and needs about $17,500 to make it.

We’d really like to see this one succeed, and not just because PortableSDR took 3rd place in the 2014 Hackaday Prize. Many a time we’ve heard people forecast the death of amateur radio (ham if you will). The ham community is special, it’s a great way to get mentorship in electronics, and deals in more than just digital circuitry. Plus, as [Greg] has pointed out, having a license and some know-how lets you build and operate really powerful stuff!

We see the PortableSDR as one way to renew interest in the hobby. We especially like it that you don’t need a license to operate the basic model — the transmitting circuits aren’t enabled when it arrives. This means you can learn about SDR, explore what’s going on over the airwaves, and only then take the leap by applying for your license and hack the unit to transmit. To be fair, the transmitter portion of the project hasn’t been published yet, which is about the only real concern we read in the Kickstarter comments. But we have faith that [Michael] will come through with that part of it. And if he needs help we’re sure he’ll have no problem finding it.

Now’s the time… let’s pull this one out in the final days!

Get Serious With Amateur Radio; Design & Build A Single-Sideband Transceiver From Scratch Part 1

February 2, 2015 by 53 Comments

Amateur radio is the only hobby that offers its licensed operators the chance to legally design, build, and operate high power radio transceivers connected to unlimited antenna arrays for the purpose of communicating anywhere in the world. The most complicated part of this communication system is the single-sideband (SSB) high frequency (HF) transceiver. In reality, due to the proliferation of low-cost amateur equipment, there only exists a very small group of die-hards who actually design, build from scratch, and operate their own SSB transceivers. I am one of those die-hards, and in this post I will show you how to get started.

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Transmitting Data Long-Distance With Morse Code

November 12, 2014 by 61 Comments

[Konstantinos] wrote in to tell us about his CDW project: a digital encoding scheme for ham radio that uses CW (continuous wave) Morse code for digital data transfer. [Link updated 1/5/16] CW operation with Morse code is great for narrow-bandwidth low-speed communication over long distances. To take advantage of this, [Konstantinos] developed a program that takes binary or text files, compresses them, and translates them to a series of letters and numbers that can be represented with Morse code.

The software translates the characters into sequences of Morse code pulses, and plays an audio stream of the result. His software doesn’t support decoding Morse from an audio stream, so [Konstantinos] recommends using one of many existing programs to get the job done. Alternatively those with a good ear and working knowledge of Morse can transcribe the characters by hand.

After receiving a broadcast, the user pastes received characters back in the software. The software re-assembles the binary file from the Morse characters and decompresses the result. [Konstantinos] also added a simple XOR encryption feature, but keep in mind that using encryption on ham radio bands is technically illegal.

ham radio

Fox Hunting With A Raspberry Pi

November 6, 2014 by 11 Comments

No, not a real fox! [KM4EFP] is a ham radio operator with a passion for fox hunting, which is an event where several radio operators attempt to find a broadcasting beacon (a “fox”) using radio direction finding techniques. [KM4EFP] has just built his own portable fox using a Raspberry Pi in a very well-built enclosure.

Since the fox could be outside for a while, the project was housed in a reasonably weatherproof ammunition case. A mount for an antenna was attached to the side, and it is hooked up to a GPIO pin on the Raspberry Pi. The entire device is powered by a 6000 mAh battery pack which allows the fox to broadcast long enough to be found.

The software running on the Raspberry Pi is very similar to the Pi FM transmitter program but it is specially made for ham radio broadcasting instead. Almost no extra hardware is needed to get the Pi broadcasting radio, as these software packages can drive the antenna directly from the GPIO pin. This is a great twist on the standard FM transmitter that ham radio enthusiasts everywhere can use to start finding those wily foxes!