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Hackaday Prize Semifinalist: Big Data and Big Agriculture

พฤ, 09/10/2015 - 12:00

For their entry to the Hackaday Prize, the team behind SentriFarm is solving a big problem for farmers in Australia. Down there, farms are big, and each paddock must be checked daily. This means hours of driving every day. Surely a bunch of sensors and some radio links would help, right?

This is the idea behind SentriFarm: a ground station that reads air temperature, atmospheric pressure, wind speed and direction, rain, light, UV and smoke, and relays that back to a central node. Yes, it’s basically a wireless weather station, but the sheer distance these sensors must transmit adds some interesting complexity.

The SentriFarm team is hoping to get about 10km out of their radio system, and they’re using a long-range, low power radio module to do it. This data is received by the ubiquitous radio towers found on Australian farms and sent to a database on the farm’s network. This data can be combined with data from the local weather service to get an accurate picture of exactly what’s happening in each paddock.

You can check out the SentriFarm project video below.

The 2015 Hackaday Prize is sponsored by:

Filed under: green hacks, The Hackaday Prize

Turning Smog Into Gemstones And Pollution Awareness

พฤ, 09/10/2015 - 09:00

Wait what? The Smog Free Project by [Daan Roosegaarde] is another one of those head scratchers where somehow art, engineering, and a designer collide — to produce what looks like an actual working concept…?

The oddly shaped white tower is essentially a massive air purifier. It’s in Rotterdam this week after over 3 years of research and development. It actually scrubs the air, removes contaminates, and then compresses those particles down into small cubes, or “gem stones”. Going full tilt, it will clean approximately 30,000 cubic meters of air per hour.

To help spread awareness, they then take the waste cubes and integrate them into jewelry. Essentially they’re physical carbon credits!

The project was originally intended for Beijing for obvious reasons, but since then has grown to become what [Dan] hopes to be a movement. So instead this odd white tower will be traveling around the globe to help spread awareness of pollution — they’re using a Kickstarter to try to generate some funding to help with transportation costs. It will make it to Beijing by the way, which is where Studio Roosegaarde is located.

This is the same guy who made the glow in the dark sidewalk in the Netherlands, reminiscent of [Vincent Van Gogh’s] Starry Night — which we have to admit, was actually pretty cool — replacing light posts with a ground that glows.

What do you think of the idea? We can’t imagine it’s very efficient, but who knows…

Filed under: green hacks

Smart Phone Camera Turns Laser Cutter into Hi-Res Scanner

พฤ, 09/10/2015 - 06:00

Getting decent macro photos always seems to be a chore. Some important detail always seems to be just outside of the depth of field, or you have to be zoomed in so close that you get great detail in one spot but miss the big picture. [Nate B] had such a problem while trying to document some PC boards, and he came up with a nifty hack that uses a laser cutter and a smart phone camera to do the job.

Click for detail.

Having first tried scanning the boards with a flat-bed scanner but finding the depth of field unsatisfactory, [Nate B] then went on to his Samsung phone’s camera. Set to panorama mode, he manually scanned across the boards and let the camera stitch the images together. The results were better, but the wobblies got the better of him and the images showed it. He then decided to use a laser cutter — with the laser disabled, of course — as an impromptu X-Y stage to raster his camera above the boards. In a slightly cringe-worthy move, he gingerly clamped the phone to the cutter gantry, started the panorama, and let the cutter move over the board. This results in a rock-solid pictures of his boards with a lot of detail – perfect for his documentation. As a bonus, the honeycomb laser cutter bed makes for an interesting background texture.

Obviously anything could be used to raster a camera and achieve similar results, but full points here for maximizing available resources and not over-complicating a simple job. Yet another reason you can use to justify that laser-cutter purchase.

Filed under: digital cameras hacks, misc hacks

Press Amazon Dash Button, Summon Uber

พฤ, 09/10/2015 - 03:01

Modern life is complicated. When you want to call an Uber car to pick you up, you have to open the app, sign in and set your pickup location. [Geoffrey Tisserand] uses Uber to commute to his job in San Francisco every day, so he came up with a neat way to automate this process, by reprogramming an Amazon Dash button to call an Uber. All he has to do is to hit the button, and a few minutes later an Uber rolls up to his door.

To do this, he used the intercept method, where a Python script running on another computer notices the Amazon Dash button joining his home WiFi network and posts the request to Uber. Because Uber uses the OAuth authentication system, he was able to easily log into the system using Expressjs. And because he is always following the same route, he could also automate the posting of the pickup and dropoff locations, as they don’t change. It’s a neat hack that saves him time, but it doesn’t get around the issue of letting you know how long the car will take to arrive, or if Uber is in Surge Pricing. Perhaps that would work for version 2: a small button with an LCD screen and a warning light.

Filed under: transportation hacks

Steal This Ham Radio (Technology)

พฤ, 09/10/2015 - 00:01

Although I see a lot of wireless projects, I’m always surprised at the lack of diversity in the radio portions of them. I’m a ham radio operator (WD5GNR; I was licensed in 1977) and hams use a variety of radio techniques. If you think hams just use Morse code and voice communications, you are thinking of your grandfather’s ham radio. Modern hams have gone digital and communicate via satellites, video, and many different digital techniques that could easily have applicability to different wireless projects.

Of course, Morse code may have been one of the first digital modes. But hams have used teletype, FAX, and other digital modes for years. Now with PCs and soundcards in common use, hams have been on the forefront of devising sophisticated digital radio techniques.

The motivation for devising unique digital modes is two fold. First, hams don’t have unlimited bandwidth, especially in the high frequency (HF) bands that allow for long distance communications. Anything that takes less bandwidth is welcome. Second, HF bands have rough characteristics. Signals fade, atmospheric noise causes static and crashes, and other stations cause interference. There are other special cases too, like bouncing signals off meteors where the right digital strategy can significantly improve odds of getting messages through.

One of the first of these soundcard methods was PSK31. This mode uses a very low symbol rate and encodes data by using phase transitions. To avoid high frequency harmonics, the phase shifts occur only at zero crossings. The 31 in the name refers to the 31.25 baud rate (that’s not K baud, that’s baud; just more than 30 bits per second). To help make up for the slow baud rate, the system employs a variable length code so common letters use shorter bit patterns. Of course, the bandwidth used is also about 31Hz, so that’s one benefit.

Hams use software to decode all the signals in their receiver’s audio at once. Historically, you wanted to filter away all the signals except the one you are listening to. With PSK31, you want a wide filter and you let the DSP home in on all the signals, filtering each one digitally. For example, the picture below shows a waterfall display of several PSK31 signals coming in at one time. The waterfall is a special graph where the X axis (left to right) is frequency and the Y axis (vertical) is time. The “worms” crawling down the waterfall are signals (you can also see the snow of random noise). The PC can read data from all the signals at once easily.

Digital sound card modes have become even more sophisticated from there. One ham, [WB8NUT], has an interesting page that summarizes many modes and includes sound clips. Different modes have different purposes. For example, packet is an adaptation of X.25 over radio frequencies and can be used as a physical layer for TCP/IP. JTMS is useful for meteor scatter and JT65 for moonbounce (yes, that’s what it sounds like) and can enable slow data transfer with signals inaudible to the human ear. Many of these protocols use forward error correction and use sophisticated codes like Reed-Solomon for error detection and correction.

Even voice has gone digital. We covered that earlier and the linked YouTube video (and the picture, right) shows a voice contact (a QSO) that is difficult to understand using regular analog transmissions, but is perfectly clear using the digital techniques. Better performance and reduced bandwidth all thanks to PC-based DSP. Then again, not all solutions require DSP, but widespread adoption has been due to the ease of development and use with a common PC.

My point isn’t related to any particular mode, though (if you really want to see a demo of PSK31, check out the video below). In the non-Ham community, we see people build new computer languages, operating systems, and even CPUs. But it is pretty rare to see new radio modulation schemes. With few exceptions, hackers buy radios and take what they get with them.

If you want to experiment with little or no investment, check out WebSDR (see picture below). With the right Web browser, you can borrow someone’s radio (which is cool all by itself) and then route audio into one of the many digital mode programs (like fldigi, for example). To start, look for a radio that is in a part of the world where it is day time, tuned in the 20 meter band, and look at 14.070 for PSK31 activity. Note that in the screen shot, I was one of 147 users listening to the radio at one time and we didn’t all have to listen to the same thing.

Maybe the hacker community could take a cue from the hams. Radio experimentation has a lot of potential. Granted, it is a little easier because hams have radio frequencies where they are allowed to experiment. Yet there are digital and voice bands available to everyone and (depending on your local laws) it might be interesting to see just how much data you could ship over such an audio channel. Or you could bite the bullet and become a ham yourself (that’s a lot easier than it used to be in most countries including the United States).

Challenging? You bet. But really, no more challenging than a scanning tunneling microscope or building a custom CPU. Who’s up for it?

Filed under: Hackaday Columns, rants, wireless hacks

Saturday in Washington DC: Hackaday Meetup

พุธ, 09/09/2015 - 23:01

If you’re in the DC area, clear your schedule this Saturday night. Hackaday is hosting a Meetup at Nova Labs starting at 6pm. All you need to do is let us know you’re planning to attend.

The Reston, Virginia hackerspace is minutes away from Dulles airport. If you haven’t stopped by the hackerspace since they moved this is a great chance to see the new location. Bring along any hardware you’re working on. You can give a lightning talk about it, or just show it off casually while enjoying some food and beverage. Several members of the Hackaday crew will be on hand: [Anool Mahidharia] will be in town presenting a weekend-long workshop on PCB design using KiCAD. [Mike], [Brian], and [Sophi] will join him for the meetup on Saturday evening. For more details on what is going down that weekend take a look at the original announcement post. See you soon!

Filed under: Hackerspaces

Aerogel Insulation for 3D Printers

พุธ, 09/09/2015 - 22:01

A heated bed is nearly essential for printing with ABS. Without it, it is difficult to keep parts from warping as the plastic cools. However, heating up a large print bed is difficult and time consuming. It is true that the printer easily heats the hot end to 200C or higher and the bed’s temperature is only half of that. However, the hot end is a small insulated spot and the bed is a large flat surface. It takes a lot of power and time to heat the bed up and keep the temperature stable.

We’ve used cork and even Reflectix with pretty good results. However, [Bill Gertz] wasn’t getting the performance he wanted from conventional material, so he got a piece of aerogel and used it as insulation. Aerogel material is a gel where a gas replaces the liquid part of the gel. Due to the Knudsen effect, the insulating properties of an aerogel may be greater than the gas it contains.

Due to a bad measurement, [Bill] had to work the gel with a hobby knife. The aerogel was the only exotic material needed. A little Kapton tape (which hardly seems exotic these days), scissors, whiteboard markers, and a hobby knife did the trick.

We’ve covered how to make your own aerogels although it takes some exotic materials and gear. There’s plenty of recipes on the Internet and YouTube (see below).

Filed under: 3d Printer hacks, tool hacks

Exponential Growth In Linear Time: The End Of Moore’s Law

พุธ, 09/09/2015 - 21:01

Moore’s Law states the number of transistors on an integrated circuit will double about every two years. This law, coined by Intel and Fairchild founder [Gordon Moore] has been a truism since it’s introduction in 1965. Since the introduction of the Intel 4004 in 1971, to the Pentiums of 1993, and the Skylake processors introduced last month, the law has mostly held true.

The law, however, promises exponential growth in linear time. This is a promise that is ultimately unsustainable. This is not an article that considers the future roadblocks that will end [Moore]’s observation, but an article that says the expectations of Moore’s Law have already ended. It ended quietly, sometime around 2005, and we will never again see the time when transistor density, or faster processors, more capable graphics cards, and higher density memories will double in capability biannually.

Chip Frequency graphed against year of introduction. Source: The Future of Computing Performance (2011)

In 2011, the Committee on Sustaining Growth in Computing Performance of the National Research Council released the report, The Future of Computing Performance: Game Over or Next Level? This report provides an overview of computing performance from the first microprocessors to the latest processors of the day.

Although Moore’s Law applies only to transistors on a chip, this measure aligns very well with other measures of the performance of integrated circuits. Introduced in 1971, Intel’s 4004 has a maximum clock frequency of about 700 kilohertz. In two years, according to bastardizations of Moore’s Law, this speed would double, and in two years double again. By around 1975 or 1976, so the math goes, processors capable of running at four or five Megahertz should appear, and this was the historical precedent: the earliest Motorola 6800 processors, introduced in 1974, ran at 1MHz. In 1976, RCA introduced the 1802, capable of 5MHz. In 1979, the Motorola 68000 was introduced, with speed grades of 4, 6, and 8MHz. Shortly after Intel released the 286 in 1982, the speed was quickly scaled to 12.5 MHz. Despite being completely different architectures with different instruction sets and bus widths, a Moore’s Law of the clock speed has existed for a very long time. This is law also holds true with the performance and even TDP per device.

Number of transistors, performance, clock speed, power, and cores per chip, graphed over time Source: The Future of Computing Performance (2011).

Everything went wrong in 2004. At least, this is the thesis of The Future of Computing Performance. Since 2004, the exponential increase in performance, both in floating point and integer calculations, clock frequency, and even power dissipation has leveled off.

One could hope that the results are an anomaly and that computer vendors will soon return to robust annual improvements. However, public roadmaps and private conversations with vendors reveal that single threaded computer-performance gains have entered a new era of modest improvement.

There was never any question Moore’s Law would end. No one now, or when the law was first penned in 1965, would assume exponential growth could last forever. Whether this exponential growth would apply to transistors, or in [Kurzweil] and other futurists’ interpretation of general computing power was never a question; exponential growth can not continue indefinitely in linear time.

Continuations of a recent trend

The Future of Computing Performance was written in 2011, and we have another half decade of data to draw from. Has the situation improved in the last five years?

Unfortunately, no. In a survey of Intel Core i7 processors with comparable TDP, the performance from the first i7s to the latest Broadwells shows no change from 2005 through 2015. Whatever happened to Moore’s Law in 2005 is still happening today.

The Future Of Moore’s Law

Even before 2011, when The Future of Computing Performance was published, the high-performance semiconductor companies started gearing up for the end of Moore’s Law. It’s no coincidence that the first multi-core chips made an appearance around the same time TDP, performance, and clock speed took the hard turn to the right seen in the graphs above.

A slowing of Moore’s Law would also be seen in the semiconductor business, and this has also been the case. In 2014, Intel released a refresh of the 22nm Haswell architecture because of problems spinning up the 14nm Broadwell architecture. Recently, Intel announced they will not be introducing the 10nm Cannonlake in 2016 as expected, and instead will introduce the 14nm Kaby Lake in 2016. Clearly the number of transistors on a die can not be doubled every two years.

While the future of Moore’s Law will see the introduction of exotic substrates such as indium gallium arsenide replacing silicon, this much is clear: Moore’s Law is broken, and it has been for a decade. It’s no longer possible for transistor densities to double every two years, and the products of these increased densities – performance and clock speed – will remain relatively stagnant compared to their exponential rise in the 80s and 90s.

There is, however, a saving grace: When [Gordon Moore] first penned his law in 1965, the number of transistors on an integrated circuit saw a doubling every year. In 1975, [Moore] revised his law to a doubling every two years. Here you have a law where not only the meaning – transistors, performance, or speed – can change, but also the duration. Now, it seems, Moore’s law has extended to three years. Until new technologies are created, and chips are no longer made on silicon, this will hold true.

Filed under: computer hacks, Featured

Hack Puts Aging Sprinkler System Online

พุธ, 09/09/2015 - 18:01

Water conservation is on a lot of people’s mind, and with an older sprinkler system one may not have the finest control of when and where the lawn is getting its water. Faced with such a system [Felix] decided to hack into his, adding better computerized scheduling, and internet remote control.

The brains of the operation is handled by a Moteino, which is a Arduino compatible micro controller board with WiFi on board. In order to interface with the sprinkler system, an interface PCB is made. The interface has an on board buck power supply to regulate the 24 volt AC power of the sprinkler down to 5 volt DC for the micro and the 74HC595 shift registers.

The output from the shift registers connects to a pin header where the stock computer normally would have plugged in. With a little software and a phone app, the new micro-controller takes over the sprinkler’s TRIAC’s turning on and off zones with a push of the thumb.

Join us after the break for a quick demonstration video.

Filed under: Android Hacks, Arduino Hacks, home hacks

Video FPGA with No External A/D

พุธ, 09/09/2015 - 15:01

You have an old PC with a nonstandard RGB video out and you need to bring it to a modern PAL TV set. That’s the problem [svofski] had, so he decided to use an Altera-based DE1 board to do the conversion. Normally, you’d expect reading an RGB video signal would take an analog to digital converter, which is not typically present on an FPGA. Instead of adding an external device, [svofski] used a trick to hijack the FPGA’s LVDS receivers and use them as comparators.

The scheme does take a few discrete components to level shift the input signal and to provide an RC integrator. The integrator is used as a digital to analog converter, allowing the FPGA to compare the incoming signal with an output voltage. Once the analog signal is digitized, it is relatively straightforward to convert it to any format you want. Going back to the analog domain is as simple as a pulse width or pulse density modulation scheme and an RC filter (or you could use a simple R2R DAC).

The result is a very low parts count project that gets the job done. Of course, this is a complete hack of the LVDS I/O in the FPGA. If you want to hear more about the real use of LVDS, see the video below.

Filed under: FPGA, video hacks

Hackaday Prize Semifinalist: Smart Medication Dispenser

พุธ, 09/09/2015 - 12:00

The biggest problems with pharmaceuticals isn’t patents, industry reps, or the fact that advertisement to consumers is allowed; this only happens in the United States. No, the biggest problem with pills and medications is compliance, or making sure the people who are prescribed medication take their medication. For his Hackaday Prize entry, [Joe] is working on a solution. It’s a smart desktop medicine organizer, and you can think of it as a pill box with smarts.

The list of features of [Joe]’s organizer include automatic pill organization – each prescription is accessed independently of all the others. When it’s time to take a pill, the smart medication dispenser plops out a pill. You can check out the demo video [Joe] put together using M&M candies.

There are a few more features for the Smart Desktop Medicine Organizer, including connecting to pharmacy APIs to order refills, checking for drug interactions, and setting timers (or not) for different medications; meds that should be taken every day will be dispensed every day, but drugs taken as needed up to a maximum limit will be dispensed as needed.

It’s a very cool project, and you can check out [Joe]’s video for the project below.

The 2015 Hackaday Prize is sponsored by:

Filed under: Medical hacks, The Hackaday Prize

Arduino TinyGPS Updated To Support GLONASS

พุธ, 09/09/2015 - 09:01

GPS is a global technology these days, with the Russian GLONASS system and the forthcoming European Galileo orbiting alongside the original US GPS satellites above our heads. [Florin Duroiu] decided to embrace globalism by forking the TinyGPS library for the Arduino platform to add support for these satellite constellations.

In addition to the GLONASS support, the new version of the venerable TinyGPS adds some neat new features by incorporating the NMEA 3.0 standard (warning: big-ass PDF link). Using this, you can extract interesting stuff such as the calculated position from each satellite constellation, the signal strength of each satellite and a lot more technical stuff about what the satellites are saying about you to your GPS receiver. [Florin] claims it is a drop-in replacement for TinyGPS that should require no rewriting. There is no support for Galileo just yet (as the satellites are still being launched: eight are in orbit now), but [Florin] is looking for help to add this, as well as the new Chinese BEIDOU system once it is operational.

(top image: artists’ view of a Galileo satellite in orbit, courtesy of ESA)

Filed under: Arduino Hacks

The iPad Controlled Camera Slider

พุธ, 09/09/2015 - 06:01

[Daniel] and [Tobias] dabble in videography and while they would love a camera slider controlled by their favorite iDevice, commercial motorized camera sliders are expensive, and there’s no great open source alternative out there. They decided to build one for themselves that can be controlled either from a PS3 controller or from its own iPad app with the help of an ESP8266 WiFi module.

The camera slider is a two-axis ordeal, with one axis sliding the camera along two solid rails, and the other panning the camera. The circuit board was milled by the guys and includes an ATMega328 controlling two Pololu stepper drivers. An ESP8266 is thrown into the mix, and is easily implemented on the device; it’s just an MAX232 chip listening to the Tx and Rx lines of the WiFi module and translating that to something the ATMega can understand.

By far the most impressive part of this project is the iPad app. This app can be controlled ‘live’ and the movements can be recorded for later playback. Alternatively, the app has a simple scripting function that performs various actions such as movement and rotation over time. The second mode is great for time lapse shots. Because this camera slider uses websockets for the connection, the guys should also be able to write a web client for the slider, just in case they wanted the ultimate webcam.

You can check out [Daniel] and [Tobias]’ demo reel for their camera slider below.

Filed under: cnc hacks, digital cameras hacks

Finally, an Official Display for the Raspberry Pi

พุธ, 09/09/2015 - 03:01

Yes, finally, and after years of work and countless people complaining on forums, there is a proper, official display for the Raspberry Pi.

It’s a 7-inch display, 800 x 480 pixel resolution, 24-bit color, and has 10-point multitouch. Drivers for the display are already available with a simple call of sudo apt-get update, and the display itself is available at Newark, the Pi Store (sold out) and Element14. There’s even a case available, and a stand ready to be sent off to a 3D printer.

As for why it took so long for the Raspberry Pi foundation to introduce an official display for the Pi, the answer should not be surprising for any engineer. It’s EMC, or electromagnetic compliance. The DPI (Display Parallel Interface) for the Pi, presented on the expansion header and used by the GertVGA adapter allows any Pi to drive two displays at 1920 x 1024, 60FPS. This DPI interface is an electrical nightmare that spews RF interference everywhere it goes.

The new display could have used the DSI (Display Serial Interface) adapter, or the small connector on the Pi that is not the camera connector. DSI displays are purpose-built for specific devices, though, and aren’t something that would or should be used in a device that will be manufactured for years to come. The best solution, and the design the Raspberry Pi foundation chose to go with, is a DPI display and an adapter that converts the Pi’s DSI output to something the display can understand.

The solution the Pi foundation eventually settled on is an adapter board that converts the DSI bus to DPI signalling. This of course requires an extra PCB, and the Foundation provided mounting holes so a Pi can connect directly to it.

While this is the first display to make use of the DSI interface, it will assuredly not be the last. The Pi Foundation has given us a way to use the DSI connector to drive cheap DPI displays. While the 800×480 resolution of the official display may be a bit small, there will undoubtedly be a few hardcore tinkerers out there that will take this adapter board and repurpose it for larger displays.

[Alex Eames] got his hands on the Pi Display a few weeks ago, you can check out his introductory video below.

Filed under: Raspberry Pi

See Actual Microwaves — No More Faking It

พุธ, 09/09/2015 - 00:01

Last week we saw a lot of interest in faux visualization of wireless signals. It used a tablet as an interface device to show you what the wireless signals around you looked like and was kind of impressive if you squinted your eyes and didn’t think too much about it. But for me it was disappointing because I know it is actually possible to see what radio waves look like. In this post I will show you how to actually do it by modifying a coffee can radar which you can build at home.

The late great Prof. David Staelin from MIT once told me once that, ‘if you make a new instrument and point it at nature you will learn something new.’ Of all the things I’ve pointed Coffee Can Radars at, one of the most interesting thus far is the direct measurement and visualization of 2.4 GHz radiation which is in use in our WiFi, cordless phones (if you still have one) and many other consumer goods. There is no need to fool yourself with fake visualizations when you can do it for real.

Modify the MIT Coffee Can Radar

The MIT Coffee Can Radar has introduced the study of radar, electromagnetics, RF/analog design, and signal processing to hundreds of curious students, hackers, and veteran engineers. It is used in both private, government labs, turned into full semester courses at other universities, and has even been featured on Mongolian National Television.

We will use this radar to directly image a 2.4 GHz microwave field emitted from its own transmitter.

The radar will be configured to show the time-varying 2.4 GHz field as if time is standing still. To do this we configure the radar to work in Doppler mode. This radar is unique in that you can DC couple the output of its front-end frequency mixer, thereby creating what is sometimes called a ‘micro Doppler’ measurement device. With this the output of the frequency mixer is a voltage proportional to phase and amplitude of the scattered signal from whatever radar target the radar is pointed at. If you stand in front of the radar in this mode and walk towards it and away from it you will see a slowly time varying waveform directly proportional to where you are standing.

To visualize wireless radiation, I’ve modified the op-amp circuit on the output of this mixer so that it can feed a pair of LEDs, one red and one green. These are wired opposite polarity. I then un-mounted the receiver cantenna, attached an extension microwave cable, and taped the LEDs (with extension wires) to the top of the can. With this new antenna assembly I can freely walk the receiver antenna around my lab with the LEDs attached to it providing me an optical indication of phase and amplitude of the transmitted carrier.

Block diagram.

When you move the receive cantenna around in front of the transmitter cantenna you will see the LEDs vary from red to green to red, back and forth, tracking the wavefront being radiated out of the transmit cantenna.

To capture the image of the 2.4 GHz wireless wave front, the aperture of a DSLR is left open while the receive cantenna is moved around near the front of the transmitter antenna. All of this must be done in a darkened room.

What 2.4 GHz wireless signals actually look like

If the above description is confusing then watch this video:

This is what 2.4 GHz wireless radiation looks like. From these measurements you can see the wave front curvature as it exits the transmitting cantenna. As we approach the distance 2d^2/lambda (where d = diameter of the transmitting cantenna) we can see the wave front turning into a plane wave. Also, you can see that the brightness of the LEDs drops as the inverse distance from the transmitter, just as one might expect.

Yes, there is granularity to this image limited by how much patience I had for moving the receiver assembly around in front of the transmitter. For the above image I spent about 1-2 minutes. For more fine detail spend more time moving the receiver assembly around while the DSLR shutter is open.

For each wireless router in your home or office this is what the radiated fields look like.

IEEE Microwave Theory and Techniques Association (MTT) Video Competition

This work helped to spur an innovative competition sponsored by IEEE MTT where some of these methods were used for a variety of scenarios and the results are amazing (scroll to about 2 min into video below):

Your turn

Its well within your ability to measure and observe the nature of wireless propagation. See for yourself what wireless signals look like propagating through your lab and your home. If you’re still not convinced that this is for you, take a look at [David Schneider’s] Coffee Can Radar presentation, and my own video demonstrations of Doppler shift using the hardware.

Author Bio

Gregory L. Charvat likes to image wireless radiation, is the author of Small and Short-Range Radar Systems, a visiting research Scientist at MIT Media Lab, co-founder of Hyperfine Research Inc. and Butterfly Network Inc. Greg is editor of the G. L. Charvat Series on Practical Approaches to Electrical Engineering. Greg is a former staff member at MIT Lincoln Laboratory, where he created the MIT Through Wall Radar the MIT Build a Radar course. In addition to this, he has done many more things and is involved in lots of interesting stuff.

Filed under: Featured, radio hacks

Only Eat Red Skittles? We’ve Got You Covered.

อังคาร, 09/08/2015 - 22:31

Are you a bit obsessive compulsive with lots of certain things? We are too. Like Skittles! If you’re the kind of person who likes to sort their Skittles, you should seriously look into making your own 3D printed Skittles Sorter.

Built more to challenge his new 3D printer, [MrPrezident] was looking for a project to combine mechanical design with a bit of image recognition prowess — so he came up with this clever, and compact, Skittle sorting machine.

It uses an Arduino Uno with a ZITRADES color sensor module to identify the color of each candy. A small LED helps illuminate the Skittles to ensure an accurate color reading. Then, depending on the color, a series of gears rotate the Skittles piece to its designated color repository.

Theoretically it should also work with M&M’s (which are a bit smaller) but unfortunately, there are 6 colors of M&M’s and only 5 colors of Skittles. What would the machine do then!? We don’t see a reject bin!

Regardless, we’re quite impressed with how compact he ended up making it — [MrPrezident] has certainly been keeping up with his STEM promises!

And if you need something a bit faster to satiate your OCD… try this one instead. It’s capable of sorting Skittles or M&M’s at a rate of 80 pieces per minute!

Filed under: 3d Printer hacks, Arduino Hacks

How Biohackers are Fighting a Two-front War on Antibiotic Resistance

อังคาร, 09/08/2015 - 21:01

We humans like to think of ourselves as the pinnacle of evolution on the planet, but that’s just a conceit. It takes humans roughly twenty years to reproduce, whereas some bacteria can make copies of themselves every 20 minutes. Countless generations of bacteria have honed and perfected their genomes into extremely evolved biological machines.

Most bacteria are harmless, and some are quite useful, even tasty – witness the lactofermented pickles and sauerkraut I made this summer. But some bacteria are pathogenic nightmares that have swarmed over the planet and caused untold misery and billions of deaths. For most of human history it has been so – the bugs were winning. Then a bright period dawned in the early 20th century – the Era of Antibiotics. At last we were delivered from the threat of pestilence, never more to suffer from plague and disease like our unfortunate ancestors. Infections were miraculously cured with a simple injection or pill, childhood diseases were no longer reaping their tragic harvest, and soldiers on the battlefield were surviving wounds that would have festered and led to a slow, painful death.

Now it seems like this bright spot of relief from bacterial disease might be drawing to an end. Resistant strains of bacteria are in the news these days, and the rise of superbugs seems inevitable. But is it? Have we run out of tools to fight back? Not quite yet as it turns out. But there’s a lot of work to do to make sure we win this battle.

Artificial Selection in Action

Alexander Fleming [via Wikipedia]So what exactly is going on here? Why are we losing the war against microbes? I think the first thing we need to keep in mind is that the age of universally effective antibiotics is actually not that old. The antibiotic properties of Penicillium molds were only first explored in 1928, but Alexander Fleming’s famous discovery languished until the 1940s, when mass-production of penicillin from fungal cultures was perfected. That’s not very long at all, and a time when a simple infection could literally eat a person alive in a couple of days is very much within the living memories of millions of people.

In the 75 years since then, huge advancements in antibiotic therapy beyond penicillin have been made, and literally millions of lives have been saved by the tetracyclines, sulfonamides, cephalosporins and quinolones that have followed it. Each antibiotic class has its own method of action, and each medicine has a particular niche that it exploits – penicillins disrupt bacterial cell wall synthesis, for example, while tetracyclines inhibit protein synthesis in bacterial ribosomes. But each little trick that we exploit to kill off bacteria has an unintended consequence – it leaves survivors behind. Random mutations and genetic reassortment lead to the chance that a handful of cells in the infection will be able to resist the antibiotic being used. When the susceptible cells are killed off, the resistant cells are not only left behind, they’re left with an open playing field and tons of resources to exploit. The survivors reproduce, pass their resistance on to the next generation, and pretty soon you’ve artificially selected a population of superbugs.

Obviously it’s all a little more complicated than that. Our immune systems are hard at work during an infection, and once the susceptible cells are culled it generally does a pretty good job of mopping up the small number of resistant bacteria. And resistance does not necessarily mean “antibiotic-proof” – it might just mean a cell is able to put up more of a fight to the antibiotic of choice. This is the reason for long courses of antibiotic therapy – knock the infection back with the first dose or two, then keep the levels of the medicine up to keep up the pressure on the tougher bugs so the immune system can mop up. Quit the medicine early, and you’re just giving the resistant bugs a chance to explode in population and cause a real problem.

Misuse of antibiotics has also contributed to the current state of affairs. Patients generally want to walk out of their doctor’s office with something to show for the effort and expense, and being told to go home and wait out a viral infection often doesn’t sit well. Going home with a useless course of antibiotics used to be a common practice and has no doubt contributed to the selection of the resistant strains of bacteria we’re seeing today.

Ancient Wisdom

But isn’t there a disconnect here? If we are so susceptible to bugs, and we only figured out how to fight them off less than a century ago, how did we even get this far as a species? While it’s true that modern antibiotics are only a recent development, traditional treatment of infection goes back a lot further. Traces of tetracycline, which strongly binds to the mineral matrix of bones and teeth, can be found in human skeletal remains from 1700 years ago. It’s not clear whether they were purposely dosing themselves or just picking up tetracycline from naturally occurring soil bacteria, but they were exposed and probably benefited from it.

[Source: AncientBiotics Project]Going back about a thousand years, there’s evidence of a more directed approach to antibiotic therapy. The University of Nottingham’s AncientBiotics Project is a combination of history and molecular microbiology that’s recreating antibiotic recipes from Anglo-Saxon texts and testing their efficacy. Following the detailed Viking-era instructions and using carefully sourced ingredients, they produced a medicine that was not only effective against cultures of Staphylococcus aureus, the bug behind deadly MRSA infections, but also managed to destroy tough-to-kill biofilms of S. aureus in an artificial skin infection system. It’s pretty remarkable to think that a brew of garlic, onions, wine and ox gall can accomplish what modern antibiotics can no longer do, but it appears the Dark Ages had some bright spots after all. Could there be a wealth of similar recipes in ancient texts? My guess is yes – humans have always put a lot of effort into staying alive, and while a lot of traditional therapies are clearly quackery, there has always been a tendency to apply rational thought and scientific methods to problems. We just need to get past modern biases that traditional remedies are all somehow backward. After all, we might look at a recipe for medicine containing “the bluish mould from a slice of rough bread, three days aged” as nonsense, but it’s a pretty good description of how penicillin was discovered.

What’s Next?

As fruitful as it may prove to tap into ancient wisdom, the fact remains that the microbes will always be one step ahead of us. Whether we throw a new synthetic molecule or an ancient potion at an infection, random mutations and generation times measured in minutes will combine to quickly evolve resistance to the next therapy. But what if there was a way to strip antibiotic resistance from bacteria? Then no matter what new tricks they learn, we’d be able to sensitize them to antibiotics and maybe gain a little ground in the fight against infection.

CRISPR/Cas9 [Source: GEN]Enter CRISPR, or clustered regularly interspaced short palindromic repeats.  CRISPRs are part of an immune system for bacteria – a way for populations of bugs to share immunity to bacteria-specific viruses, called phages. When a phage invades a bacterium, a snippet of the injected DNA is copied into a CRISPR region, providing a memory of the attacker. The CRISPRs are shared around the bacterial population so that eventually all the cells learn what an attack looks like, and when that happens, the bugs pull out their secret weapons – special enzymes called CRISPR-associated proteins (Cas) that can cleave DNA. Now when a phage tries to attack, CRISPR sequences are transcribed to RNA, which has the “memorized” phage sequences in it. The RNA binds tightly to the foreign DNA, which allows the Cas enzymes to chop the DNA up and prevent the infection.

CRISPR is a really powerful tool for gene editing, and one that has applications for overcoming antibiotic resistance. In an ironic twist, researchers are packing CRISPR/Cas systems into phages and using them to attack bacteria. The CRISPR system is programmed to search for and destroy the sequences that code for antibiotic resistance, like the beta-lactamase protein that confers penicillin resistance. The bacteria are then vulnerable to antibiotics they had previously been able to stand up to.

There are limits to what CRISPR can accomplish in the fight against infection. One obvious problem is finding a phage that attacks each bug you want to kill, and being able to genetically modify it with a CRISPR payload. And the bugs still have the evolutionary upper hand, since they can rapidly try out random mutations that may overcome the CRISPR attack. But it’s at least another tool for us to use, and one that allows us to rapidly respond to new threats. Moreover, it’s a very approachable technology in terms of equipment and instrumentation. Indeed, CRISPR has become the hot new technique for biohackers who seek to create everything from better yeasts for craft brewed beers to vegan cheese. Perhaps some of these biohackers will turn their attention to the problem of antibiotic resistance too.

Even though the evolutionary deck is clearly stacked against us, I don’t think we’re done for quite yet. While the bugs have the numbers, we have our own evolutionary gift – a great big forebrain. If we put enough of them on the problem, some breakthrough will happen. So while the Era of Antibiotics isn’t necessarily at an end, it probably is at a really interesting inflection point.

[MRSA SEM Image via Wikipedia]

Filed under: Featured, Medical hacks

How to Upgrade a Chinese CNC Machine

อังคาร, 09/08/2015 - 18:01

Looking to add a small CNC machine to your garage or hackerspace’s arsenal of tools? Like any tools — China has you covered for the cheap options — but the question is, is it worth it? Typically it depends on the tool, but when you can upgrade your 3040 CNC router to use USB instead of a parallel port with the TinyG motion controller… most definitely!

The 3040 or 3020 CNC router is a popular Chinese machine used by many hobbyists — and for good reason. A rigid all-aluminum frame, decent stepper motors and pretty good resolution? It’s not a bad deal for around $1000USD. We’ve covered it many times before. Problem is, the electronics are a bit out-dated. Particularly in the fact that it uses Mach3 with a parallel port… Come on, who has a parallel port these days?

[John Lauer] set out to fix this. The TinyG is a motor controller we’ve covered a few times before as well — it was just waiting to be fitted into a 3040 CNC in order to run a better control system, like ChiliPeppr!

In fact, [John] ordered the CNC machine just to do this upgrade — and he’s sharing how he did it with everyone:

And while you’re at it, why not add spindle direction and coolant control to your 3040 CNC as well? Or how about learning how to machine foam, and then cast it into solid aluminum?

Filed under: cnc hacks

Pulse Density Modulation

อังคาร, 09/08/2015 - 15:01

[esot.eric] was trying to drive a motor and naturally thought of using pulse width modulation (PWM) to control the motor speed. However, he found that even with a large capacitor, his underpowered power supply would droop before the PWM cycles were complete. So instead of PWM he decided to experiment with pulse density modulation.

The idea is to use smaller pulses over a longer period of time and make the average power equal to the percentage motor speed desired. With a PWM system, for example, if the time period is T, a 50% PWM drive would have the  drive high for T/2 and low for the other half of the cycle. With pulse density, each pulse might be T/10 (as an example) and then the output would be on for 1/10, off for 1/10, on for 1/10 and so on, until by time T you’d still get to 50%. The advantage is the output capacitor gets a kick more often and has less opportunity to droop.

You probably want a scope to measure PWM or pulse density, but we’ve talked about how to do it scopeless before. If you want to go old school, think about how to do pulse density with a 555 chip and post it on Hackaday.io.

Filed under: Microcontrollers

Hackaday Prize Semifinalist: Playing With PIDs

อังคาร, 09/08/2015 - 12:00

PID control loops are everywhere, found in flight controllers for drones and the temperature control code for 3D printers. How do you teach PID control loops? [Tim] has a great demonstration for this, and it’s also a semifinalist for the Hackaday Prize.

[Tim]’s Sab3t is an educational tool designed to illustrate how PID control loops work. It’s a robotic table on which a large ball bearing sits perfectly balanced. On this table is a resistive touch screen from a display providing feedback for the location of the ball bearing. By adjusting PID values, the ball bearing either sits stationary on the table or flails wildly around, depending on the values in the PID algorithm being used.

As a teaching tool, it’s great; with a python script displaying a log of the PID values and the position of the ball on the plate, anyone can easily visualize how oscillations happen, what a well-tuned control loop looks like, and have some fun moving the ball bearing around to different locations.

The 2015 Hackaday Prize is sponsored by:

Filed under: The Hackaday Prize