A rubidium standard, or rubidium atomic clock, is a high accuracy frequency and time standard, usually accurate to within a few parts in 1011. This is still several orders of magnitude less than some of the more accurate standards – for example the NIST-F1 has an uncertainty of 5×10-16 (It is expected to neither gain nor lose a second in nearly 100 million years) and the more recent NIST-F2 has an uncertainty of 1×10-16 (It is expected to neither gain nor lose a second in nearly 300 million years). But the Rb standard is comparatively inexpensive, compact, and widely used in TV stations, Mobile phone base stations and GPS systems and is considered as a secondary standard.
The obvious way of checking would be to use another source with a higher accuracy, such as a caesium clock and do a phase comparison. Since that was not possible, he decided to use NIST’s time/frequency service, broadcasting on 60 kHz – WWVB. He did this because almost 30 years ago, he had built a receiver for WWVB which had since been running continuously in a corner of his shop, with only a minor adjustment since it was built.
His idea was to count and accumulate the phase ‘slips’ generated by comparing the output of the WWVB receiver with the output of the Rb standard using a digital phase comparator. The accuracy of the standard would be calculated as the derivative of N (number of slips) over time. The circuit is a quadrature mixer: it subtracts the frequency of one input from the other and outputs the difference frequency. The phase information is conveyed in the duty cycle of the pulses coming from the two phase comparators. The pulses are integrated and converted to digital logic level by low-pass filter/Schmitt trigger circuits. The quadrature-phased outputs are connected to the stepper motor driver which converts logic level inputs to bi-directional currents in the motor windings. The logic circuit is bread-boarded and along with the motor driver, housed in a computer hard drive enclosure which already had the power supply available.
Since early evening on September 5th, 2013 the US National Institute of Standards and Technology (NIST) has been publishing a 512-bit, full-entropy random number every minute of every day. What’s more, each number is cryptographically signed so that you can easily verify that it was generated by the NIST. A date stamp is included in the process, so that you can tell when the random values were created. And finally, all of the values are linked to the previous value in a chain so that you can detect if any of the past numbers in the series have been altered after the next number is published. This is quite an extensive list of features for a list of random values, and we’ll get into the rationale, methods, and uses behind this scheme in the next section, so stick around.
We’ve seen a wide variety of hacks that keep time, but [ch00f]’s latest build takes a new spin on counting the seconds. The Gutenberg Clock keeps time by reading books on a scrolling LED screen.
The content for the clock is sourced from the Project Gutenberg, which releases books with expired copyright for free. The library on the clock consists of around twenty thousand such books. Read at eighty words per minute, the clock won’t repeat a passage for the next thirty-three years.
While the clock doesn’t display time itself, it is synchronized to time. Two identical clocks should display the same text at the same time. To get the time, [ch00f] first tried hacking apart a cheap radio clock, which is synchronized to NIST’s 60 kHz broadcast. After reverse engineering the protocol with great success, stray RF energy from the display turned out to cause too much interference.
With the cheap solution out the window, [ch00f] built a custom breakout for an Adafruit GPS module and used it to get the time. This was his first RF board, but it worked out fine.
Books are loaded onto a FAT filesystem on an SD card, and [ChaN]’s FatFS is used to interpret the filesystem. A microcontroller then sends the text out at a constant rate to a serial port on the display which he hacked his way into.
The project is a neat mix of art and electronics. Stick around for a video overview after the break.
Defcon keeps announcing more and more interesting events for next week’s conference. A free workshop is planned for the soon to be released DAVIX live CD. DAVIX is a collection of tools for data analysis and visualization. They’ll be running through a few example packet dumps to demonstrate how the tools can help you make sense of it all. [Thomas Wilhelm] will be driving out from Colorado Springs in his Mobile Hacker Space. He’s giving a talk Sunday, but will be giving presentations a few hours every day at the van. Some researchers from NIST will be setting up a four node quantum network and demonstrating some of the possible vulnerabilities in the system. Finally, as part of an EFF fundraiser, Defcon will feature a Firearms Training Simulator. Conference attendees will participate in drills designed to improve their speed, accuracy, and decision making skills.
Medgadget recently published a post about a soccer competition for nanobots at RoboCup. The nanobots compete on a field that measures 1500 by 2500 micrometers with goals on the long sides jutting 500 micrometers out. Like normal soccer athletes, the nanobot teams attempt to push the ball – in this case, a silicon dioxide disc with a 50 micrometer diameter – into the goal. The nanobot competitors are monitored by an optical microscope and are remotely controlled by magnetic signals sent across the arena.
The National Institute of Standards and Technology (NIST) and RoboCup have already held two nanobot competitions in the last year. Nanobots made by different teams from various universities compete to test various abilities that will be critical for their practical applications in medicine, manufacturing, and other industries.
Though it is referred to as nanosoccer, the competition is actually a triathlon. The bots must sprint to the goal with the ball in one event, then maneuver the ball around stationary “defenders” and into the goal in the next event, and finally score as many goals as possible within 3 minutes. NIST and RoboCup hope to show the practical potential of nanobots with this competition and have a little fun in the process.