Hackaday Prize Entry: Multispectral Imaging Based On LandSat 7

The Landsat series of earth observing satellites is one of the most successful space programs in history. Millions of images of the Earth have been captured by Landsat satellites, and those images have been put to use for fields as divers as agriculture, forestry, cartography, and geology. This is only possible because of the science equipment on these satellites. These cameras capture a half-dozen or so spectra in red, green, blue, and a few bands of infrared to tell farmers when to plant, give governments an idea of where to send resources, and provide scientists the data they need.

There is a problem with satellite-based observation; you can’t take a picture of the same plot of land every day. Satellites are constrained by Newton, and if you want frequently updated, multispectral images of a plot of land, a UAV is the way to go.

[SouthMade]’s entry for the Hackaday Prize, uSenseCam, does just that. When this open source multispectral camera array is strapped to a UAV, it will be able to take pictures of a plot of land at wavelengths from 400nm to 950nm. Since it’s on a UAV and not hundreds of miles above our heads, the spacial resolution is vastly improved. Where the best Landsat images have a resolution of 15m/pixel, these cameras can get right down to ground level.

Like just about every project involving imaging, the [SouthMade] team is relying on off-the-shelf camera modules designed for cell phones. Right now they’re working on an enclosure that will allow multiple cameras to be ganged together and have custom filters installed.

While the project itself is just a few cameras in a custom enclosure, it does address a pressing issue. We already have UAVs and the equipment to autonomously monitor fields and forests. We’re working on the legality of it, too. We don’t have the tools that would allow these flying robots to do the useful things we would expect, and hopefully this project is a step in the right direction.


The 2015 Hackaday Prize is sponsored by:

Pneumatic Multiplexer

This is a pretty cool project [Sebastian Morales] is working on – a 3D printed Pneumatic Multiplexer. Large interactive installations, kinetic art and many other applications require large numbers of actuators to be controlled. For these type of projects to work, a large number of actuators equals higher resolution and that allows the viewer to be captivated by the piece.

The larger the system becomes, the more complex it becomes to control all of those actuators. [Sebestian] wanted to move a large number of components with a relatively low number of inputs. He thought of creating a mechanical equivalent of the familiar electronic X-Y matrix that can control large quantities of outputs using only a few inputs – in a more descriptive form, Outputs=(Inputs/2)^2.

airlogic_01He looked at chemical reactions that change liquids in to gases, but that seemed pretty complicated. Refrigerants used in air conditioning looked promising, but their handling and safety aspects looked challenging.

Eventually, he decided to look at using “air logic“. Air logic uses pneumatic devices to create relays, limit switches, AND gates, NAND gates, OR gates, amplifiers, equivalent to electrical circuits. Electrical energy is replaced with compressed air. His plan was to build a multiplexer whose elements would open only if the combination of pressure between both lines was the right one. As in electronics, NAND logic is easy to implement. A moving element creates a seal and only allows air out if the bottom line was low and the top line was high.

He had access to a high resolution, resin based 3D printer which allowed him to create fully air-tight systems. He started with prototyping a small 4×4 matrix to test out his design, and had to work through 6 to 7 iterations before he could get it to work. The next step was to create a larger matrix of 100 elements controlled by 20 inputs (10×10 matrix). He created Omnifarious – a kinetic sculpture demonstrating the concept of shapeshifting objects. The Omnifarious is a hexecontahedron which would be able to transform its surface to render different geometries via 59 balloons on its surface. Below, you can check the videos of his progress building the various prototypes and another video showing the Omnifarious sculpture.

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Discrete Transistor Computer Is Not Discreet

Every few years, we hear about someone building a computer from first principles. This doesn’t mean getting a 6502 or Z80, wiring it up, and running BASIC. I’m talking about builds from the ground up, starting with logic chips or even just transistors.

[James Newman]’s 16-bit CPU built from transistors is something he’s been working on for a little under a year now, and it’s shaping up to be one of the most impressive computer builds since the days of Cray and Control Data Corporation.

The 10,000 foot view of this computer is a machine with a 16-bit data bus, a 16-bit address bus, all built out of individual circuit boards containing single OR, AND, XOR gates, decoders, multiplexers, and registers.  These modules are laid out on 2×1.5 meter frames, each of them containing a schematic of the computer printed out with a plotter. The individual circuit modules sit right on top of this schematic, and if you have enough time on your hands, you can trace out every signal in this computer.

The architecture of the computer is more or less the same as any 16-bit processor. Three are four general purpose registers, a 16 bit program counter, a stack pointer, and a status register. [James] already has an assembler and simulator, and the instruction set is more or less what you would expect from a basic microprocessor, although this thing does have division and multiplication instructions.

The first three ‘frames’ of this computer, containing the general purpose registers, the state and status registers, and the ALU, are already complete. Those circuits are mounted on towering frames made of aluminum extrusion. [James] already has 32 bytes of memory wired up, with each individual bit having its own LED. This RAM display will be used for the Game of Life simulation once everything is working.

While this build may seem utterly impractical, it’s not too different from a few notable and historical computers. The fastest computer in the world from 1964 to ’69 was built from individual transistors, and had even wider busses and more registers. The CDC6600 was capable of running at around 10MHz, many times faster than the estimated maximum speed of [James]’ computer – 25kHz. Still, building a computer on this scale is an amazing accomplishment, and something we can’t wait to see running the Game of Life.

Thanks [aleksclark], [Michael], and [wulfman] for sending this in.

Remove Security Issues From Untrusted USB Connections

USB has become pretty “universal” nowadays, handling everything from high-speed data transfer to charging phones. There are even USB-powered lava lamps. This ubiquity doesn’t come without some costs, though. There have been many attacks on smartphones and computers which exploit the fact that USB is found pretty much everywhere, and if you want to avoid these attacks you can either give up using USB or do what [Jason] did and block the data lines on the USB port.

USB typically uses four wires: two for power and two for data. If you simply disconnect the data lines, though, the peripheral can’t negotiate with the host for more power and will limp along at 0.5 watts. However, [Jason] discovered that this negotiation takes place at a much lower data rate than normal data transfer, and was able to put a type of filter in between the host and the peripheral. The filter allows the low-frequency data transfer pass through but when a high-frequency data transfer occurs the filter blocks the communication.

[Jason] now has a device that can allow his peripherals to charge at the increased rate without having to worry about untrusted USB ports (at an airport or coffee shop, for example). This simple device could stop things like BadUSB from doing their dirty work, although whether or not it could stop something this nasty is still up in the air.

Retrotechtacular: Don’t Balk At Pitch-Up In The McDonnell F-101 Voodoo

The McDonnell aircraft corporation’s F-101 Voodoo was a lean, mean, supersonic machine capable of going from tarmac to 40,000 feet in about two minutes. But for all its innovation and engineering, the Voodoo had a common problem of pitch-up. That is, the swept-back wings of the Voodoo created a tendency for the plane to nose upward very sharply, negating the pilot’s control.

McDonnell assures Voodoo pilots that this problem is easily overcome with a cool head and a solid foundation of know-how about the issue. This training film is meant to provide that foundation, exploring the causes of pitch-up and the prescribed methods for recovery with and without deployment of the drag chute.

The drag chute is always the recommended route to help correct the craft. This is especially true for a full-scale pitch-up situation. Recovery is possible without the drag chute, however. The altitude lost in recovery is proportional to the altitude at the time that pitch-up occurs. That is, the lower the altitude of the craft when pitch-up occurs, the less altitude is lost in getting back to straight and level flight.

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The Shady World Of Drone Racing

No one noticed the two men in the alley as the darkness of midnight approached – their long, black trench coats acting like a soldier’s camouflage.

“You got the goods?”

“Yeah, these are hot man…super fast..check this…”

The bark of a police siren broke their whispered conversation like a shattering glass, causing the two men to briefly freeze in their steps.

“Johnny B. got busted last week…did you hear?”

“No way man! What he get busted for?”

“Drone racing man…drone racing.”

Deep within the shadows of abandoned warehouses and dilapidated factories on the outskirts of Australian suburbia, the telltale buzz of numerous drones can be heard. Zipping to and fro at speeds upwards of 60km/h, these drones are not just flying. They’re racing each other. The operators use specialized FPV goggles that allow them to see the raceway in real time. This method, unfortunately, puts them on the wrong side of the law.

The dated laws governing drones in Australia are similar to those in the US, which were written for the radio controlled plane industry. While they technically forbid any flying outside of line-of-site, the Australian Civil Aviation Authority seems to be OK with the drone racing so long as it’s done indoors and poses no risk to people or property.

Know of any drone racing in your country? Is it legal? Do people do it anyway? Let us know in the comments.

Down-Draft Table Keeps The Shop Dust Free

Wood working is great but it can certainly get the shop dusty. [BigD] is a wood worker and needed a way to keep his shop from getting super dusty while sanding or routing. He ended up making a pretty slick dual-use downdraft table with a hidden filtration system.

The table’s frame is made from standard 2-by dimensional lumber you’d likely see most shop tables made from. It was built so that the top of the table would be flush with the table of the table saw. This allows the down-draft table to also act as an out feed support for the table saw, making it easier to cut longer pieces of wood.

To allow airflow to pull any generated dust down, a plethora of holes were drilled in the table top. Down below are a couple sealed chambers, one for the incoming dust and one for the air blower that creates the down-draft air flow. The two chambers are separated by a pair of filters which keep the dust from being blown back into the shop. A little door on the side of the table allows access to clean out the accumulated dust and debris. Now [BigD] can sand up a storm on his down-draft table without breathing in a sapling worth of dust.