Tattoos are an ancient art, and as with most art, is usually the domain of human expertise. The delicate touch required takes years to master, but with the capacity for perfect accuracy and precision movements, enlisting a robotic arm and some clever software to tattoo a willing canvas is one step closer thanks to the efforts of [Pierre Emm] and [Johan da Silveira].
They began by using a 3D printer modified to ‘print’ with a tattoo needle. Catching the interest of the Applied Research Lab at Autodesk, the next logical step was to use an industrial robot arm get a human under the tattooing machine — dubbed Tatoué — after scanning the limb in question and loading it into Dynamo, their parametric design environment to map the design onto the virtual limb.
One of the big stories of last year was the fracture of the official Arduino supply into two competing organisations at daggers drawn, each headed by a different faction with its origins in the team that gave us the popular single board computers. Since then we’ve had Arduinos from Arduino LLC (the [Massimo] Arduino.cc, arguably the ‘original’, and Arduino trademark holder in the United States) and Arduino SRL (the [Musto] Arduino.org, and owner of the Arduino trademark everywhere except the US) , two websites, two forks of the IDE, and “real” Arduino boards available under a couple of names depending on where in the world you live due to a flurry of legal manoeuvres. Yes. it’s confusing.
Today came news of a supplier throwing its hands up in despair at the demands imposed on them as part of this debacle. Pimoroni, famous as supplier of Raspberry Pi goodies, has put up a blog post explaining why they will henceforth no longer be selling Arduinos. They took the side of Arduino LLC, and the blog post details their extensive trials and delays in making contact with the company before eventually being told they would have to agree to purchase substantial stocks both Arduino and Genuino branded versions of identical products and agree to sell them through separate supply channels for both Europe and the rest of the world before they could proceed. This is not a practical proposition for a small company, and the Pimoroni people deliver a very pithy explanation of exactly why towards the bottom of their post.
We’ve covered the Arduino versus Arduino debacle extensively in the past, this is simply the latest in a long line of stories. Pimoroni have hit the nail on the head when they make the point that the customers and suppliers really don’t care about spats between the various inheritors of the Arduino legacy, they just want an Arduino. And with so many other Arduino-compatible boards available they don’t have to look very hard to find one if the right shade of blue solder-resist or the shape of the map of Italy on the back isn’t a special concern. Can we be the only ones wishing something like this might knock a bit of sense into the various parties?
In part one, I compared the different Analog to Digital Converters (ADC) and the roles and properties of Delta Sigma ADC’s. I covered a lot of the theory behind these devices, so in this installment, I set out to find a design or two that would help me demonstrate the important points like oversampling, noise shaping and the relationship between the signal-to-noise ratio and resolution.
Modulator Implementation
Check out part one to see the block diagrams of what what got us to here. The schematics shown below are of a couple of implementations that I played with depicting a single-order and a dual-order Delta Sigma modulators.
Basically I used a clock enabled, high speed comparator, with two polarities in case I got it the logic backwards in my current state of burn out to grey matter ratio. The video includes the actual schematic used.
Since I wasn’t designing for production I accepted the need for three voltages since my bench supply was capable of providing them and this widget is destined for the drawer with the other widgets made for just a few minutes of video time anyway. Continue reading “Tearing Into Delta Sigma ADCs Part 2”→
It doesn’t matter how many bits your password has, how proven your encryption is, or how many TrueCrypt volumes are on your computer. If someone wants data off your device, they can get it if they have physical access to your device. This is the ‘evil maid’ security scenario, named after hotel maids on the payroll of a three-letter agency. If someone has physical access to a laptop – even for an hour or two – the data on that laptop can be considered compromised. Until now, there has been no counter to this Evil Maid scenario, and for good reason. Preventing access to data even when it is in the possession of an Evil Maid is a very, very hard problem.
When I start up a new project, one that’s going to be worth writing up later on, I find it’s useful to get myself into the right mindset. I’m not a big planner like some people are — sometimes I like to let the project find its own way. But there’s also the real risk of getting lost in the details unless I rein myself in a little bit. I’m not alone in this tendency, of course. In the geek world, this is known as “yak shaving“.
The phrase comes obliquely from a Ren and Stimpy episode, and refers to common phenomenon where to get one thing done you have to first solve another problem. The second problem, of course, involves solving a third, and so on. So through this (potentially long) chain of dependencies, what looks like shaving a yak is obliquely working on cracking some actually relevant problem. Continue reading “Yak Shaving: Hacker Mode Vs Maker Mode”→
I wanted to point out a tool that I often use, but rarely see on other people’s workbenches: thermal strippers. They aren’t cheap, but once you’ve used them, it is hard to go back to stripping wires with an ordinary tool.
I know, I know. When I first heard of such a thing, I thought what you are probably thinking now: maybe for some exotic coated wire, but for regular wire, I just use a pair of diagonal cutters or a mechanical stripper or a razor blade. You can do that, of course, and for large solid wires, you can even get good results. But for handling any kind of wire, regardless of size, you just can’t beat a thermal stripper.
Software defined radios are getting better and better all the time. The balaclava-wearing hackers know it, too. From what we saw at HOPE in New York a few weeks ago, we’re just months away from being able to put a femtocell in a desktop computer for under $3,000. In less than a year, evil, bad hackers could be tapping into your cell phone or reading your text message from the comfort of a van parked across the street. You should be scared, even though police departments everywhere and every government agency already has this capability.
These rogue cell sites have various capabilities, from being able to track an individual phone, gather metadata about who you have been calling and for how long, to much more invasive surveillance such as intercepting SMS messages and what websites you’re visiting on your phone. The EFF calls them cell-site simulators, and they’re an incredible violation of privacy. While there was most certinaly several of these devices at DEF CON, I only saw one in a hotel room (you catchin’ what I’m throwin here?).
No matter where the threat comes from, rogue cell towers still exist. Simply knowing they exist isn’t helpful – a proper defence against governments or balaclava wearing hackers requires some sort of detection system.. For the last few months [Eric Escobar] has been working on a simple device that allows anyone to detect when one of these Stingrays or IMSI catchers turns on. With several of these devices connected together, he can even tell where these rogue cell towers are.
A Stingray / cell site simulator detector
Stingrays, IMSI catchers, cell site simulators, and real, legitimate cell towers all broadcast beacons containing information. This information includes the radio channel number, country code, network code, an ID number unique to a large area, and the transmit power. To make detecting rogue cell sites harder, some of this information may change; the transmit power may be reduced if a tech is working on the site, for instance.
To build his rogue-cell-site detector, [Eric] is logging this information to a device consisting of a Raspberry Pi, SIM900 GSM module, an Adafruit GPS module, and a TV-tuner Software Defined Radio dongle. Data received from a cell site is logged to a database along with GPS coordinates. After driving around the neighborhood with his rogue-cell-site detector sitting on his dashboard, [Eric] had a ton of data that included latitude, longitude, received power from a cell tower, and the data from the cell tower. This data was thrown at QGIS, an open source Geographic Information System package, revealing a heatmap with the probable locations of cell towers highlighted in red.
This device really isn’t a tool to detect only rogue cell towers – it finds all cell towers. Differentiating between a rogue and legitimate tower still takes a bit of work. If the heatmap shows a cell site on a fenced-off parcel of land with a big tower, it’s a pretty good bet that cell tower is legit. If, however, the heatmap shows a cell tower showing up on the corner of your street for only a week, that might be cause for alarm.
Future work on this cell site simulator detector will be focused on making it slightly more automatic – three or four of these devices sprinkled around your neighborhood would easily allow you to detect and locate any new cell phone tower. [Eric] might also tackle triangulation of cell sites with an RF-blocking dome with a slit in it revolving around the GSM900 antenna.
