Reverse Engineering An Ultrasonic Car Parking Sensor

May 16, 2017 by Jenny List 18 Comments

It has become a common sight, a must-have feature on modern cars, a row of ultrasonic sensors embedded in the rear bumper. They are part of a parking sensor, an aid to drivers for whom depth perception is something of a lottery.

[Haris Andrianakis] replaced the sensor system on hs car, and was intrigued enough by the one he removed to reverse engineer it and probe its workings. He found a surprisingly straightforward set of components, an Atmel processor with a selection of CMOS logic chips and an op-amp. The piezoelectric sensors double as both speaker and microphone, with a CMOS analogue switch alternating between passing a burst of ultrasound and then receiving a response. There is a watchdog circuit that is sent a tone by the processor, and triggers a reset in the event that the processor crashes and the tone stops. Unfortunately he doesn’t delve into the receiver front-end circuitry, but we can see from the pictures that it involves an LC filter with a set of variable inductors.

If you have ever been intrigued by these systems, this write-up makes for an interesting read. If you’d like more ultrasonic radar goodness, have a look at this sweeping display project, or this ultrasonic virtual touch screen.

Ultrasonic Tracking Beacons Rising

May 4, 2017 by Pedro Umbelino 41 Comments

An ultrasonic beacon is an inaudible sound with encoded data that can be used by a listening device to receive information on just about anything. Beacons can be used, for example, inside a shop to highlight a particular promotion or on a museum for guided tours where the ultrasonic beacons can encode the location. Or they can be used to track ~~people~~ consumers. Imagine if Google find outs… oh, wait… they already did, some years ago. As with almost any technology, it can be used to ‘do no harm’ or to serve other purposes.

Researchers from the Technische Universitat Braunschweig in Germany presented a paper about Ultrasonic Side Channels on Mobile Devices and how can they be abused in a variety of scenarios , ranging from simple consumer tracking to deanonymization. These types of ultrasonic beacons work in the 18 kHz – 20 kHz range, which the human being doesn’t have the ability to hear, unless you are under twenty years old, due to presbycusis. Yes, presbycusis. This frequency range can played via almost any speaker and can be picked up easily by most mobile device microphones, so no special hardware is needed. Speakers and mics are almost ubiquitous nowadays, so there is a real appeal to the technology.

Continue reading “Ultrasonic Tracking Beacons Rising” →

A Cool Mist That Dries Your Clothes

April 23, 2017 by Mike Szczys 77 Comments

This one is both wild enough to be confused as a conspiracy theory and common sense enough to be the big solution staring us in the face which nobody realized. Until now. Oak Ridge National Laboratory and General Electric (GE), working on a grant from the US Department of Energy (DOE), have been playing around with new clothes dryer technology since 2014 and have come with something new and exciting. Clothes dryers that use ultrasonic traducers to remove moisture from garments instead of using heat.

If you’ve ever seen a cool mist humidifier you’ll know how this works. A piezo element generates ultrasonic waves that atomize water and humidify the air. This is exactly the same except the water is stored in clothing, rather than a reservoir. Once it’s atomized it can be removed with traditional air movement.

This is a totally obvious application of the simple and inexpensive technology — when the garment is laying flat on a bed of transducers. This can be implemented in a press drying system where a garment is laid flat on a bed or transducers and another bed hinges down from above. Poof, your shirt is dry in a few seconds.

But individual households don’t have these kinds of dryers. They have what are called drum dryers that spin the clothes. Reading closely, this piece of the puzzle is still to come:

They play [sic] to scale-up the technoloogy to press drying and eventually a clothes dryer drum in the next five months.

We look at this as having a similar technological hurdle as wireless electricity. There must be an inverse-square law on the effect of the ultrasonic waves to atomize water as the water moves further away from the transducers. It that’s the case, tranducers on the circumference of a drum would be inefficient at drying the clothing toward the center. This slide deck hints that that problem is being addressed. It talks about only running the transducers when the fabric is physically coupled with the elements. It’s an interesting application and we hope that it could work in conjunction with traditional drying methods to boost energy savings, even if this doesn’t pan out as a total replacement.

With a vast population, cost adds up fast. There are roughly 125 M households in the United States and the overwhelming majority of them use clothes dryers (while many other parts of the world have a higher percentage who hang-dry their clothing). The DOE estimates $9 billion a year is spent on drying clothes in the US. Reducing that number by even 1/10th of 1% will pay off more than tenfold the $880,000 research budget that went into this. Of course, you have to outfit those households with new equipment which will take at least 8-12 years through natural attrition, even if ultrasonics hit the market as soon as possible.

Continue reading “A Cool Mist That Dries Your Clothes” →

Command Alexa With A Completely Mechanical Vintage Remote Control

April 2, 2017 by Cameron Coward 10 Comments

Anyone with grandparents already knows that in ye olden days, televisions did not have remote control. Your parents probably still complain about how, as children, they were forced to physically walk over to the TV in order to switch between the three available channels. In these modern times of technological wonder, we have voice control, programmable touch screen remotes, and streaming services that will automatically play an entire season of the show you’re binge watching. However, before these, and before the ubiquitous infrared remote, television manufacturers were experimenting with ways to keep kids from having to run across the living room every time the channel needed to be changed.

Early remote controls were simply wired affairs — nothing too surprising there. But, it wasn’t long before methods of wireless control were being introduced. One early effort called the Flashmatic would shine light onto a photoelectric cell on the television set to control it. Of course, it might also be controlled by unintended light sources, and users had to have good aim to hit the sensor. These issues soon led to the introduction of the Zenith Space Command remote control, which used ultrasonic frequencies to control the TV.

Continue reading “Command Alexa With A Completely Mechanical Vintage Remote Control” →

Retrotechtacular: How Old Is The Remote?

March 16, 2017 by Al Williams 69 Comments

A few weeks ago we covered a (probably) bogus post about controlling a TV with the IR from a flame. That got us thinking about what the real origin of the remote control was. We knew a story about the 38 kHz frequency commonly used to modulate the IR. We’ve heard that it was from sonar crystals used in earlier sonic versions of remotes. Was that true? Or just an urban myth? We set out to find out.

Surprise! Remotes are Old!

If you are a younger reader, you might assume TVs have always had remotes. But for many of us, remotes seem like a new invention. If you grew up in the middle part of the last century it is a good bet you were your dad’s idea of a remote control: “Get up and turn the channel!” Turns out remotes have been around for a long time, though. They just weren’t common for a long time.

If you really want to stretch back, [Oliver Lodge] used a radio to move a beam of light in 1894. In 1896, [Marconi] and some others made a bell ring by remote control. [Tesla] famously showed a radio-controlled boat in 1898. But none of these were really remote controls like we think of for a television.

Of course, TV wouldn’t be around for a while, but by the 1930’s many radio manufacturers had wired remotes for radios. People didn’t like the wires, so Philco introduced the Mystery Control in 1939. This used digital pulse coding and a radio transmitter. That’s a fancy way of saying it had a dial like an old telephone. As far as we can tell, this was the first wireless remote for a piece of consumer equipment.

Continue reading “Retrotechtacular: How Old Is The Remote?” →

Stadium Sized Cellphone Light Show Is Controlled By Sound

January 27, 2017 by Adam Fabio 35 Comments

18 months ago, [Jameson Rader] didn’t know how to code. He had an economics degree and worked for a minor league hockey team. He did have a dream, though. Broadcasting data through sound. When we say broadcast, we mean broadcast – as in one sender and thousands of receivers.

[Jameson] didn’t have the money to hire a team to build his application. So he did what any self-respecting hacker would do. He bought a few books and taught himself to code. We’re talking about a smartphone app here, so Java and Objective-C were necessary to cover Android and iOS devices. The result is XT Audio Beacons.

[Jameson] has created a light show for stadiums which requires no new hardware infrastructure. Ultrasonic cues are added to a pre-recorded soundtrack and played over the PA system. Fans attending the show simply run an app and hold up their smartphone. The app listens for the cues and turns on the camera flash. The result is a light show which can be synchronized to music, sound effects, or whatever the event calls for. Since the system relies on sound, the App only needs permissions to access the microphone. The system would still work even if the phones were in airplane mode.

Transmitting data to smartphones via ultrasonics isn’t exactly new. Amazon uses it in their Dash Buttons, and Google uses it in their OnHub. Using it as a broadcast medium in a stadium is a novel application, though. [Jameson] also has demos showing XT Audio Beacons being used for more mundane purposes – such as troubleshooting electronics, or even as an acoustic version of an iBeacon.

Most important here is that [Jameson] isn’t keeping all this new knowledge to himself. He’s published the source to his application on Github under the MIT license.

You can see the system in action – and even try it yourself, in the video after the break.

If you want to learn more about [Jameson] and his journey, definitely check out his AMA on Reddit.

Continue reading “Stadium Sized Cellphone Light Show Is Controlled By Sound” →