As you’re no doubt aware, humans are a rather noisy species. Not just audibly, like in the case of somebody talking loudly when you’re in a movie theater, but also electromagnetically. All of our wireless transmissions since Marconi made his first spark gap broadcast in 1895 have radiated out into space, and anyone who’s got a sensitive enough ear pointed into our little corner of the Milky Way should have no trouble hearing us. Even if these extraterrestrial eavesdroppers wouldn’t be able to understand the content of our transmissions, the sheer volume of them would be enough to indicate that whatever is making all that noise on the third rock orbiting Sol can’t be a natural phenomena. In other words, one of the best ways to find intelligent life in the galaxy may just be to sit around and wait for them to hear us.
Of course, there’s some pesky physics involved that makes it a bit more complicated. Signals radiate from the Earth at the speed of light, which is like a brisk walk in interstellar terms. Depending on where these hypothetical listeners are located, the delay between when we broadcast something and when they receive it can be immense. For example, any intelligent beings that might be listening in on us from the closest known star, Proxima Centauri, are only just now being utterly disappointed by the finale for “How I Met Your Mother“. Comparatively, “Dallas” fans from Zeta Reticuli are still on the edge of their seats waiting to find out who shot J.R.
But rather than relying on our normal broadcasts to do the talking for us, a recent paper in The Astrophysical Journal makes the case that we should go one better. Written by James R. Clark and Kerri Cahoy, “Optical Detection of Lasers with Near-term Technology at Interstellar Distances” makes the case that we could use current or near-term laser technology to broadcast a highly directional beacon to potentially life-harboring star systems. What’s more, it even theorizes it would be possible to establish direct communications with an alien intelligence simply by modulating the beam.
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.
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.
If you had to explain why you use one mobile messaging service over another to your grandmother, would you be able to? Does she even care about forward secrecy or the difference between a private and public key is? Maybe she would if she understood the issues in relation to “normal” human experiences: holding secret discussions behind closed doors and sending letters wrapped in envelopes.
Or maybe your grandmother is the type who’d like to completely re-implement the messaging service herself, open source and verifiably secure. Whichever grandma you’ve got, she should watch [Roland Schilling] and [Frieder Steinmetz]’s talk where they give both a great introduction into what you might want out of a secure messaging system, and then review what they found while tearing apart Threema, a mobile messaging service that’s popular in Germany. Check out the slides (PDF). And if that’s not enough, they provided the code to back it up: an open workalike of the messaging service itself.
This talk makes a great introduction, by counterexample, to the way that other messaging applications work. The messaging service is always in the middle of a discussion, and whether they’re collecting metadata about you and your conversations to use for their own marketing purposes (“Hiya, Whatsapp!”) or not, it’s good to see how a counterexample could function.
The best quote from the talk? “Cryptography is rarely, if ever, the solution to a security problem. Cryptography is a translation mechanism, usually converting a communications security problem into a key management problem.” Any channel can be made secure if all parties have enough key material. The implementation details of getting those keys around, making sure that the right people have the right keys, and so on, are the details in which the devil lives. But these details matter, and as mobile messaging is a part of everyday life, it’s important that the workings are transparently presented to the users. This talk does a great job on the demystification front.
This isn’t the first time we’ve seen DIYers sending music over a laser beam but the brothers [Armand] and [Victor] are certainly in contention for sending the music the longest distance, 452 meter/1480 feet from their building, over the tops of a few houses, through a treetop and into a friend’s apartment. The received sound quality is pretty amazing too.
In case you’ve never encountered this before, the light of the laser is modulated with a signal directly from the audio source, making it an analog transmission. The laser is a 250mW diode laser bought from eBay. It’s powered through a 5 volt 7805 voltage regulator fed by a 12V battery. The signal from the sound source enters the circuit through a step-up transformer, isolating it so that no DC from the source enters. The laser’s side of the transformer feeds the base of a transistor. They included a switch so that the current from the regulator can either go through the collector and emitter of the transistor that’s controlled by the sound source, giving a strong modulation, or the current can go directly to the laser while modulation is provided through just the transistor’s base and emitter. The schematic for the circuit is given at the end of their video, which you can see after the break.
They receive the beam in their friend’s apartment using solar cells, which then feed a fairly big amplifier and speakers. From the video you can hear the surprisingly high quality sounds that results. So check it out. It also includes a little Benny Hill humor.
I think the restaurant is really close now… CC: E. Broeks
The best way to pull off this deception: tell your significant other that you’d want nothing more than a romantic week in Paris. Arrive in Paris, stash your bags, and then take either the number three or eleven Metro. When you get to the station that looks like the inside of a giant steam engine, Arts et Métiers, get out. You’re now ten Euros away from one of the coolest museums a hacker could visit.
A significant portion of modern science’s beginnings is sitting in the Musée, polished and beautiful. Most of them are housed in cabinets so old they’re part of the exhibit. Now, the Henry Ford museum in Detroit Michigan is a monument to industrialization, and cool in its own right, but it leaves some questions unanswered. We’re all spoiled by desktop CNCs, precision measurement tools for pennies, and more. How did we get here? How did they measure a shaft or turn a screw before precision digital micrometers? What did early automation look like? Early construction?
Also did I mention it has Foucault’s Pendulum? You know, the one that finally convinced everyone that the Earth rotated around an axis? No big deal.
The museum has a few permanent exhibits: instruments scientifique, matériaux, construction, communication, énergie, mécanique et transports.
What kind of basic museum would have just one example of Pascal’s work? CC: Anton Lefterov
Instruments Scientifiques was one of my favorites. Not only did it include old scientific instruments, it had sections containing some of the original experiments in optics, computation, and more. For example you can see not just one but a few original examples of Pascal’s Pascaline, arguably the first mechanical calculators in the modern era to be used by the layman for every day calculation, signed by Pascal. It’s also worth noting just how incredible the workmanship of these tools are. They’re beautiful.
Matériaux was initially a disappointment as I entered it from the wrong end. For me it started of with a tragically boring and simplistic display on recycling materials designed primarily to torture children on field trips. Luckily it quickly ramped into a fascinating display on materials manufacturing technology. How did we go from hand looms to fully automated Jacquard looms (of which you can see some of the first examples) to our modern day robotic looms? How did ceramic evolve? What was early steelmaking like? It’s very cool and models are all in beautiful condition.
It reeked of copper, machine oil, and phenolics. They just don’t make computers like they used to.
By the time I got to Communication I was reaching the limit of my endurance and also what you can fit into a single day of the museum. It’s a large building. It was packed through many of the early examples of computing, television, and space. There was quite a display of early camera equipment. You could get close enough to some truly massive old computers to smell the still off-gassing phenolics.
Construction held my interest for a long time. It’s not my usual interest, but after living in Paris for a month or so I was absolutely burning with curiosity. How did anyone without a single powered crane or vehicle build so many buildings out of stone? It’s packed for four rooms and two stores from floor to ceiling of beautiful little wood models explaining exactly how.
Énergie was quite cool. It followed the development of steam power for the most part. It started with primitive waterwheels. Moved on to turbines. Then showed the gradual increase in complexity until the the modern day. It had some internal combustion too, but much of that was reserved for the transports section of the museum. It also had some interactive displays to entertain children and Hackaday writers. However they were in desperate need of an oiling and this is by far the most ear-piercingly squeaky exhibit in the whole building.
Mécanique is competing with instruments scientifique as my favorite exhibit. Have you ever wanted to see hundreds of examples of screw machines, old lathes, and the evolution of the milling machine? What about models of the factories that built steam engines or massive wagon wheels. They even had a lathe that belonged to a French king. Apparently he thought metalworking was the way to get in touch with the common people.
Transports was a nice exhibit, but it fell a little short for me since I’d been to the aforementioned Henry Ford museum. However, it covered the history of some of the European automobile manufacturers pretty well. Had a nice section on trains and subways. And even had some models of the ships used in the European Space Agency.
The entrance of the school. Has some original, “flying,” machines. CC: King Boshi
The last exhibit is the museum itself. It’s an historic building. It was originally built as a school for training engineers in 1794 but as the school grew out of it, it slowly transformed into the museum it is today. The architecture is beautiful. It’s adorned in stone and statue like all the French museums. It also has sections cut out in some of the higher storeys of the building so you can see how it was constructed.
Part of its beauty is also related to the school swallowing up the Priory of Saint Martin des Champs (Google translate does a great job if you don’t read French). The Priory is a beautiful old church, founded in 1079. It was home to the last trial by combat the country would see. You can piece together the story between the two pages dedicated to the combatants Jean de Carrouges and Jacques Le Gris.
The muses of agriculture and industry now look over the sanctuary.
The final display in the museum is in the church. It holds Foucault’s pendulum, dangling from the center of the sanctuary. If you get there early enough in the day you may get to watch it knock over a peg or two and prove the rotation for yourself.
Rather than the statues of the saints there are statues of the muses of Industrie and Agriculture. The hall is filled with more exhibits. There are cutaway original automobiles. A model of the Statue of Liberty. A catwalk lets you take a high view of the surroundings. It is also beautiful in and of itself. The church is well maintained and painted in the style original to them.
If you find yourself in Paris with a few hours (or days) to spare I highly recommend this museum. Any technical person would be hard pressed to leave uninspired and unawed by the display. It’s good to get a perspective on the past.
News corporation [British Pathé] created many newsreels and documentaries throughout their 60-year history. Recently, the company released scores of films from their archives and put them on the internet. Here is a delightful collection of short films they created that highlight strange and wonderful inventions in various fields, including transportation and communication.
One of the standout inventions is the Dynasphere, a mono-wheeled vehicle that probably deserves its own week in the Retrotechtacular spotlight. There are a couple of pedal-powered planes that may have inspired the Gossamer Condor, and a hover scooter that resembles an air hockey striker and doubles as a leaf blower. In another film, a man drives a Vespa to the banks of the Thames and parks it. He pulls a fin down from each side of the scooter, turning it into a seafaring craft. When he snaps his fingers, a cute girl appears from somewhere just outside the frame. She climbs on the back, and they take off across the water.
The average running time of these films is about two minutes. Some of them are much shorter, prompting many questions. Fortunately, most of the video descriptions have links with more information about these marvelous inventions. Almost all of the inventors in these films show a complete disregard for safety, but nearly everyone involved seems to be having the time of their lives.
