Radio Hacks

1322 Articles

Listening To An IPhone With AM Radio

September 18, 2020 by 38 Comments

Electronic devices can be surprisingly leaky, often spraying out information for anyone close by to receive. [Docter Cube] has found another such leak, this time with the speakers in iPhones. While repairing an old AM radio and listening to a podcast on his iPhone, he discovered that the radio was receiving audio the from his iPhone when tuned to 950-970kHz.

[Docter Cube] states that he was able to receive the audio signal up to 20 feet away. A number of people responded to the tweet with video and test results from different phones. It appears that iPhones 7 to 10 are affected, and there is at least one report for a Motorola Android phone. The amplifier circuit of the speaker appears to be the most likely culprit, with some reports saying that the volume setting had a big impact. With the short range the security risk should be minor, although we would be interested to see the results of testing with higher gain antennas. It is also likely that the emission levels still fall within FCC Part 15 limits.

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The Interactive Storytelling Radio

September 13, 2020 by 3 Comments

[8BitsAndAByte] are back and this time they’re using AI to create an interactive storyteller. With the help of a Raspberry Pi, they upcycled an old Cold War era radio they dug up and the results are pretty impressive.

The main controller board of the radio was intact, so it was easy to use all the preexisting hardware to control the speaker and to trigger a few of the Pi’s GPIO using the buttons and switches on the radio’s front panel. To add some artificial intelligence, they used Google’s AIY Voice Kit, allowing them to tap into Google’s seemingly endless artificial intelligence platform. This could be a “tables have turned moment,” but we’re probably being a bit too hopeful.

Anyway, they used a pretty interesting piece of software called Dialogflow that creates a somewhat natural conversational interaction akin to a chatbox. Dialogflow processes speech to text, as you would expect, but can also interpret contextual speech and provide contextual responses. Pretty neat…but maybe also a little creepy. Who knows? The jury is still out.

Anyway, if you’re like us and sometimes in need of a break from humans, then this project just might be for you.

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ISS Ham Radio Repeater

September 10, 2020 by 28 Comments

There is a long history of spacecraft carrying ham radio gear, as the Space Shuttle, Mir, and the ISS have all had hams aboard with gear capable of talking to the Earth. However, this month, the ISS started operating an FM repeater that isn’t too dissimilar from a terrestrial repeater. You can see [TechMinds] video on the repeater, below.

The repeater has a 2 meter uplink and a 70 centimeter downlink. While you can use a garden variety dual-band ham transceiver to use the repeater, you’ll probably need a special antenna along with special operating techniques.

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Cell Phone Signal Booster Gets Teardown And Demo

September 10, 2020 by 7 Comments

Ever wonder what was inside a cell phone booster, or what it is like to set up or use one? If so, [Kerry Wong]’s got you covered with his teardown of a Cel-Fi Go X Cell Signal Booster by Nextivity. [Kerry] isn’t just ripping apart a cheap unit for laughs; his house has very poor reception and this unit was a carefully-researched, genuine investment in better 4G connectivity.

The whole setup consists of three different pieces: the amplifier unit pictured above, and two antennas. One is an omnidirectional dome antenna for indoors, and the other is a directional log-periodic dipole array (LPDA) antenna for outdoors. Mobile phones connect to the indoor antenna, and the outdoor antenna connects to the distant cell tower. The amplifier unit uses a Bluetooth connection and an app on the mobile phone to manage settings and actively monitor the device, which works well but bizarrely doesn’t seem to employ any kind of password protection or access control whatsoever.

Overall [Kerry] is happy, and reports that his mobile phone enjoys a solid connection throughout his house, something that was simply not possible before. Watch a hands-on of the teardown along with a short demonstration in the video embedded below.

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Tutorial For Setting Up Raspberry Pi For Ham Radio Use

September 8, 2020 by 9 Comments

There was a time when a ham radio set up sported many dials and switches and probably quite a few boxes as well. Computers have changed all that. Some transceivers now have just a few buttons or are even totally computer-controlled. Where a ham, at one time, might have a TeleType machine, a slow-scan TV monitor, and a fax printer for receiving satellite images, now that can all be on a single computer which can even be a Raspberry Pi. [F4GOH] has a post that takes you from the fundamentals to installing everything from an SDR to many common ham programs for digital modes, APRS, SSTV, and more. You can download the seven-part tutorial as separate PDF files, too.

Even if you aren’t a ham, you might find some of the software interesting. OpenWebRX lets you listen to your software defined radio on the road. You can use other software to pick up weather satellite data.

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Teardown: Mini GPS Jammer

September 8, 2020 by 142 Comments

If you spend enough time trolling eBay for interesting electronic devices to take apart, you’re bound to start seeing suggestions for some questionable gadgets. Which is how I recently became aware of these tiny GPS jammers that plug directly into an automotive 12 V outlet. Shipped to your door for under $10 USD, it seemed like a perfect device to rip open in the name of science.

Now, you might be wondering what legitimate uses such a device might have. Well, as far as I’m aware, there aren’t any. The only reason you’d want to jam GPS signals in and around a vehicle is if you’re trying to get away with something you shouldn’t be doing. Maybe you’re out driving a tracked company car and want to enjoy a quick two hour nap in a parking lot, or perhaps you’re looking to disable the integrated GPS on the car you just stole long enough for you to take it to the chop shop. You know, as one does.

But we won’t dwell on the potentially nefarious reasons that this device exists. Hackers have never been too choosy about the devices they investigate and experiment with, and there’s no reason we should start now. Instead, let’s take this piece of gray-area hardware for a test drive and see what makes it tick.

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Recognizing Activities Using Radar

September 6, 2020 by 10 Comments

Caring for the elderly and vulnerable people while preserving their privacy and independence is a challenging proposition. Reaching a panic button or calling for help may not be possible in an emergency, but constant supervision or camera surveillance is often neither practical nor considerate. Researchers from MIT CSAIL have been working on this problem for a few years and have come up with a possible solution called RF Diary. Using RF signals, a floor plan, and machine learning it can recognize activities and emergencies, through obstacles and in the dark. If this sounds familiar, it’s because it builds on previous research by CSAIL.

The RF system used is effectively frequency-modulated continuous-wave (FMCW) radar, which sweeps across the 5.4-7.2 GHz RF spectrum. The limited resolution of the RF system does not allow for the recognition of most objects, so a floor plan gives information on the size and location of specific features like rooms, beds, tables, sinks, etc. This information helps the machine learning model recognize activities within the context of the surroundings. Effectively training an activity captioning model requires thousands of training examples, which is currently not available for RF radar. However, there are massive video data sets available, so researchers employed a “multi-modal feature alignment training strategy” which allowed them to use video data sets to refine their RF activity captioning model.

There are still some privacy concerns with this solution, but the researchers did propose some improvements. One interesting idea is for the monitored person to give an “activation” signal by performing a specified set of activities in sequence.

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