Radio Hacks

1403 Articles

Free Radio On My Phone

May 28, 2016 by 84 Comments

If you have owned Android phones, there’s a reasonable chance that as the kind of person who reads Hackaday you will at some time have rooted one of them, and even applied a new community ROM to it. When you booted the phone into its new environment it’s not impossible you would have been surprised to find your phone now sported an FM radio. How had the ROM seemingly delivered a hardware upgrade?

It’s something your cellphone carrier would probably prefer not to talk about, a significant number of phones have the required hardware to receive FM radio, but lack the software to enable it. The carriers would prefer you to pay for their data to stream your entertainment rather than listen to it for free through a broadcaster. If you are someone capable of upgrading a ROM you can fix that, but every other phone owner is left holding a device they own, but seemingly don’t own.

Across North America there is a group campaigning to do something about this situation. Free Radio On My Phone and their Canadian sister organization are lobbying the phone companies and manufacturers to make the FM radio available, and in the USA at least they have scored some successes.

We have covered numerous attempts to use the DMCA to restrict people’s access to the hardware they own, but this story is a little different. There is no question of intellectual property being involved here, it is simply that the carriers would rather their customers didn’t even know that they had bought an FM radio along with their phone. If this bothers you, thanks to Free Radio On My Phone you can now join with others and find a voice on the matter.

It’s interesting to note that many FM radio chips also support a wider bandwidth than the North American and European 88 to 108MHz or thereabouts. In parts of Asia the broadcast band extends significantly lower than this, and the chipset manufacturers make products to support these frequencies. This opens up the interesting possibility that given a suitable app a cellphone could be used to receive other services on these frequencies. Probably more of a bonus for European radio amateurs with their 70MHz allocation than for North American residents.

Via CBC News. Cellphone image: By Rob Brown [Public domain], via Wikimedia Commons.

PhD Crystal Radio Has Pizza Capacitor

May 26, 2016 by 35 Comments

Crystal radios are old news, but great fun. What would happen if a PhD designed a crystal set? By PhD we mean Pizza Hut Deliveryperson and [John Greenlee] (who may not actually be a PhD of either kind; we don’t know) gives us a good idea with his crystal radio in a pizza box.

Pizza boxes aren’t the only food-related material in this radio. [John] makes a tuning capacitor out of cake rounds. Coincidentally, he decorates the tuning capacitor to look like a pizza.

The schematic itself is unremarkable–just a common crystal set. But the construction of the chassis and the capacitor make it an interesting project. If you know a young person that has any interest in radio, a crystal receiver is a rite of passage you shouldn’t deny them and this one is certainly a novelty. The picture of a pizza takes it even one step further than this YouTube build, which is nonetheless a good resource.

The instructions are well done, although some of the parts may be slightly hard to find. Germanium diodes and high-Z earphones are not as plentiful as they used to be, although you can still find them if you look.

This pizza box rig could be a gateway drug to more serious crystal radios. Or you could go smaller and try building one in a match box.

The Booths Of Hamvention

May 25, 2016 by 12 Comments

Hamvention was last weekend in Dayton, Ohio. Last weekend was also the Bay Area Maker Faire, and if you want tens of thousands of people who actually make stuff there’s really only one place to be. Bonus: you can also check out the US Air Force Museum at Wright-Patterson AFB. The ‘Space’ hangar was closed, so that’ll be another trip next year.

The biggest draw for Hamvention is the swap meet. Every year, thousands of cars pull up, set up a few tables and tents, and hock their wares. Everything from radios from the 1920s to computers from the 1980s can be found at the swap meet. This post is not about the swap meet; I still have several hundred pictures to go through, organize, label, and upload. Instead, this post is about the booths of Hamvention. Everything imaginable could be found at Hamvention, from the usual ARRL folks, to the preppers selling expired MREs, and even a few heros of Open Hardware.

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Two Guys, A Hotel Room And A Radio Fire

May 13, 2016 by 45 Comments

Can you build a HF SSB radio transciever in one weekend, while on the road, at parts from a swap meet? I can, but apparently not without setting something on fire.

Of course the swap meet I’m referring to is Hamvention, and Hamvention 2016 is coming up fast. In a previous trip to Hamvention, Scott Pastor (KC8KBK) and I challenged ourselves to restore tube radio gear in a dodgy Dayton-area hotel room where we repaired a WW2 era BC-224 and a Halicrafters receiver, scrounging parts from the Hamfest.

Our 2014 adventures were so much fun that it drove us to create our own hacking challenge in 2015 to cobble together a <$100 HF SSB transceiver (made in the USA for extra budget pressure), an ad-hoc antenna system, put this on the air, and make an out-of-state contact before the end of Hamvention using only parts and gear found at Hamvention. There’s no time to study manuals, antennas, EM theory, or vacuum tube circuitry.  All you have are your whits, some basic tools, and all the Waffle House you can eat.  But you have one thing on your side, the world’s largest collection of surplus electronics and radio junk in one place at one time.  Can it be done?

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Software Defined Radio App Store

May 7, 2016 by 87 Comments

Software defined radios (SDRs) can–in theory–do almost anything you need a radio to do. Voice? Data? Frequency hopping? Trunking? No problem, you just write the correct software, and you are in.

That’s the problem, though. You need to know how to write the software. LimeSDR is an open source SDR with a crowdfunding campaign. By itself, that’s not anything special. There are plenty of SDR devices available. What makes LimeSDR interesting is that it is using Snappy Ubuntu Core as a sort of app store. Developers can make code available, and end-users can easily download and install that code.

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Can You Hear SamSat-218D?

May 5, 2016 by 44 Comments

Students of the Samara State Aerospace University are having trouble getting a signal from their satellite, SamSat-218D. They are now reaching out to the radio amateur community, inviting everybody with sufficiently sensitive UHF VHF band (144 MHz) equipment to help by listening to SamSat-218D. The satellite was entirely built by students and went into space on board of a Soyuz-2 rocket on April 26, 2016. This is their call (translated by Google):

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WISP Needs No Battery Or Cable

May 1, 2016 by 10 Comments

One of the problems with the Internet of Things, or any embedded device, is how to get power. Batteries are better than ever and circuits are low power. But you still have to eventually replace or recharge a battery. Not everything can plug into a wall, and fuel cells need consumables.

University of Washington researchers are turning to a harvesting approach. Their open source WISP board has a sensor and a CPU that draws power from an RFID reader. To save power during communication, the device backscatters incoming radio waves, which means it doesn’t consume a lot of its own power during transmissions.

The big  news is that TU Delft has contributed code to allow WISP to reprogram wirelessly. You can see a video about the innovation below. The source code is on GitHub. Previously, a WISP had to connect to a PC to receive a new software load.

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