sound

85 Articles

Submarine To Plane: Can You Hear Me Now? The Hydrophone Radar Connection

September 23, 2018 by 34 Comments

How does a submarine talk to an airplane? It sounds like a bad joke but it’s actually a difficult engineering challenge.

Traditionally the submarine must surface or get shallow enough to deploy a communication buoy. That communication buoy uses the same type of radio technology as planes. But submarines often rely on acoustic transmissions via hydrophones which is fancy-talk for putting speakers and microphones in the water as transmitters and receivers. This is because water is no friend to radio signals, especially high frequencies. MIT is developing a system which bridges this watery gap and it relies on acoustic transmissions pointed at the water’s surface (PDF warning) and an airplane with high-precision radar which detects the oscillations of the water.

The complexity of the described setup is mind-boggling. Right now the proof of concept is over short distances and was tested in a water tank and a swimming pool but not in open water. The first thing that comes to mind is the interference caused by waves and by aerosols from wind/wave interactions. Those challenges are already in the minds of the research team. The system has been tested to work with waves of 8 cm (16 cm measured peak to trough) caused by swimmers in the pool. That may not sound like much, but it’s about 100,000 times the surface variations being measured by the millimeter wave radar in order to detect the hydrophone transmissions. Add to that the effects of Doppler shift from the movement of the plane and the sub and you have a signal processing challenge just waiting to be solved.

This setup is very interesting when pitched as a tool for researching aquatic life. The video below envisions that transmitters on the backs of sea turtles could send communications to aircraft overhead. We love seeing these kinds of forward-thinking ocean research projects, like our 2017 Hackaday prize winner which is an open source underwater glider. Oceanic studies over long distances have been very difficult but we’re beginning to see a lot of projects chipping away at that inaccessibility.

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The VU Meter And How It Got That Way

August 9, 2018 by 44 Comments

Given its appearance in one form or another in all but the cheapest audio gear produced in the last 70 years or so, you’d be forgiven for thinking that the ubiquitous VU meter is just one of those electronic add-ons that’s more a result of marketing than engineering. After all, the seemingly arbitrary scale and the vague “volume units” label makes it seem like something a manufacturer would slap on a device just to make it look good. And while that no doubt happens, it turns out that the concept of a VU meter and its execution has some serious engineering behind that belies the really simple question it seeks to answer: How loud is this audio signal?

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Chiptunes On A Solar Panel

April 6, 2018 by 16 Comments

With its vintage sound, there’s no mistaking the unique 8-bit sound of video games from the 80s and 90s. It became so popular that eventually sparked its own genre of music known as “chiptune” for which musicians are still composing today. The music has some other qualities though, namely that it’s relatively simple from a digital standpoint. [Robots Everywhere] found that this simplicity made it perfect as a carrier for wireless power transmission.

The project acts more like a radio transmitter and receiver than it does a true wireless power transmitter, but the principle is the same. It uses a modified speaker driver and amplifier connected to a light source, rather than to a speaker. On the receiving end, there is a solar panel (essentially a large photodetector) which is wired directly to a pair of earbuds. When the chiptune is played through the amplifier, it is sent via light to the solar panel where it can be listened to in the earbuds.

The project is limited to 24,000 bytes per second which is a whole lot more useful than just beaming random audio files around your neighborhood, although that will still work. You can also use something like this to establish a long-distance serial link wirelessly, which can be the basis of a long distance communications network.

Thanks to [spiritplumber] for the tip!

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Spice Up Your Bench With 3D Printed Dancing Springs

July 29, 2017 by 5 Comments

Not all projects are made equal. Some are designed to solve a problem while others are just for fun. Entering the ranks of the most useless machines is a project by [Vladimir Mariano] who created the 3D Printed Dancing Springs. It is a step up from 3D printing a custom slinky and will make a fine edition to any maker bench.

The project uses 3D printed coils made of transparent material that is mounted atop geared platforms and attached to a fixed frame. The gears are driven by a servo motor. The motor rotates the gears and the result is a distortion in the spring. This distortion is what the dancing is all about. To add to the effect, [Vladimir Mariano] uses RGB LEDs controlled by an ATmega32u4.

You can’t dance without music. So [Vladimir] added a MEMs microphone to pick up noise levels which are used to control the servo and lights. The code, STL files and build instructions are available on the website for you to follow along. If lights and sound are your things, you must check out the LED Illuminated Isomorphic Keyboard from the past. Continue reading “Spice Up Your Bench With 3D Printed Dancing Springs” →

Introducing The Hackaday Passive Aligned Ferrite Active Quantum Crystal Nanoparticle Reference Sticker

April 1, 2017 by 60 Comments

As you know, here at Hackaday we take our audio equipment very seriously indeed. We’ve seen it all over the years and have a pretty jaded view of a lot of the audiophile products that come past our door, but once in a while along comes something that’s a bit special. That’s why today we’d like to introduce you to a new product, The Hackaday Passive Aligned Ferrite Active Quantum Crystal Nanoparticle Reference Sticker.

Here’s the problem: we’re surrounded by electrical noise. You can’t see it, you can’t touch it, and you can’t hear it, but your audio equipment can, and when that happens it will degrade your listening experience without your realising it. You might have shelled out your life savings on a top-end Hinari amp, Marc Vincent surround sound processor, Friedland carillon wire cables and a set of Saisho floor-standing speakers, but if you haven’t dealt with your system’s magnetic compatibility they’re never quite going to reach their potential and you’ll always be left wondering why your broader soundstage just doesn’t zing. You need an HPAFAQCNRS.

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The Enchanting Power Of SDDSbot

March 1, 2017 by 10 Comments

Who doesn’t love a good robot? If you don’t — how dare you! — then this charming little scamp might just bring the hint of a smile to your face.

SDDSbot — built out of an old Sony Dynamic Digital Sound system’s reel cover — can’t do much other than turn left, right, or walk forwards on four D/C motor-controlled legs, but it does so using the power of a Pixy camera and an Arduino. The Pixy reads colour combinations that denote stop and go commands from sheets of paper, attempting to keep it in the center of its field of view as it toddles along. Once the robot gets close enough to the ‘go’ colour code, the paper’s  orientation directs the robot to steer itself left or right — the goal being the capacity to navigate a maze. While not quite there yet, it’s certainly a handful as it is.

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Maglev Drummer Needs To Be Seen And Heard

December 17, 2016 by 13 Comments

Sometimes Hackaday runs in closed-loop mode: one hacker makes something, we post it, another hacker sees it and makes something else, and we post it, spiraling upward to cooler and cooler hacks. This is one of those times.

One of our favorite junk-sound-artists and musical magicians, [Gijs Gieskes], made this magnetic-levitation, rubber-band, percussive zither thing after seeing our coverage of another magnetic levitation trick. Both of them simply have a Hall sensor controlling a coil, which suspends a magnet in mid-air. It’s a dead-simple circuit that we’ll probably try out as soon as we stop typing.

But [Gijs] took the idea and ran with it. What looks like a paperclip dangles off the magnets, and flails wildly around with its tiny steel arms. These hit a zither made of rubber bands with a bamboo skewer as a bridge, pressing down on a piezo. The rest is cardboard, copper-clad, and some ingenuity. Watch it work in the video embedded below.

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