Hackaday Links: October 11, 2020

If you’re interested in SDR and digital signal processing but don’t know where to start, you’re in luck. Ben Hillburn, president of the GNU Radio Project, recently tweeted about an online curriculum for learning SDR and DSP using Python. The course was developed by Dr. Mark Lichtman, who was a lead on GNU Radio, and from the look of it, this is the place to go to learn about putting SDRs to use doing cool things. The course is chock full of animations that make the concepts clear, and explain what all the equations mean in a way that’s sure to appeal to practical learners.

It’s not much of a secret that the Hackaday community loves clocks. We build clocks out of everything and anything, and any unique way of telling time is rightly applauded and celebrated on our pages. But does the clock motif make a good basis for a video game? Perhaps not, but that didn’t stop Clock Simulator from becoming a thing. To “play” Clock Simulator, you advance the hands of an on-screen clock by pressing a button once per second. Now, thanks to Michael Dwyer, you don’t even have to do that one simple thing. He developed a hardware cheat for Clock Simulator that takes the 1PPS output from a GPS module and wires it into a mouse. The pulse stream clicks the mouse once per second with atomic precision, rendering the player irrelevant and making the whole thing even more pointless. Or perhaps that is the point.

Maybe we were a little hard on Clock Simulator, though — we can see how it would help achieve a Zen-like state with its requirement for steady rhythm, at least when not cheating. Another source of Zen for some is watching precision machining, and more precise, the better. We ran into this mesmerizing video of a CNC micro-coil winder and found it fascinating to watch, despite the vertical format. The winder is built from a CNC lathe, to the carriage of which a wire dispenser and tensioning attachment have been added. The wire is hair-fine and passes through a ruby nozzle with a 0.6 mm bore, and LinuxCNC controls the tiny back and forth motion of the wire as it winds onto the form. We don’t know what the coil will be used for, but we respect the precision of winding something smaller than a matchhead.

Dave Jones over at EEVblog posted a teardown video this week that goes to a place few of us have ever seen: inside a processor module for an IBM System/390 server. These servers earned the name “Big Iron” for a reason, as everything about them was engineered to perform. The processor module Dave found in his mailbag was worth $250,000 in 1991, and from the look of it was worth every penny. From the 64-layer ceramic substrate supporting up to 121 individual dies to the stout oil-filled aluminum enclosure, everything about this module is impressive. We were particularly intrigued by the spring-loaded copper pistons used to transfer heat away from each die; the 2,772 pins on the other side were pretty neat too.

Here’s an interesting question: what happens if an earthquake occurs in the middle of a 3D printing run? It’s probably not something you’ve given much thought, but it’s something that regular reader Marius Taciuc experienced recently. As he relates, the magnitude 6.7 quake that struck near Kainatu in Papua New Guinea (later adjusted to a 6.3 magnitude) resulted in a solid 15 seconds of shaking at his location, where he was printing a part on his modified Mendel/Prusa i2. The shaking showed up clearly in the part as the machine started swaying with the room. It’s probably not a practical way to make a seismograph, but it’s still an interesting artifact.

Your Phone Is Now Helping To Detect Earthquakes

Most people’s personal experience with seismographs begins and ends with simple childhood science experiments. Watching a pendulum make erratic marks on a piece of paper while your classmates banged on the table gave you an idea on how the device worked, and there’s an excellent chance that’s the last time you gave the concept much thought. Even among hackers, whose gear in general tends to be more technologically equipped than the norm, you’re unlikely to find a dedicated seismograph up and running.

But that’s not because the core technology is hard to come by or particularly expensive. In fact, one could say with almost absolute certainty that if you aren’t actively reading these words on a device with a sensitive accelerometer onboard, you have one (or perhaps several) within arm’s reach. Modern smartphones, tablets, and even some laptops, now pack in sensors that could easily be pushed into service as broad strokes seismometers; they just need the software to collect and analyze the data.

Or at least, they did. By the time you read this article, Google will have already started rolling out an update to Android devices which will allow them to use their onboard sensors to detect possible earthquakes. With literally billions of compatible devices in operation all over the planet, this will easily become the largest distributed sensor network of its type ever put into operation. But that doesn’t mean you’re going to be getting a notification on your phone to duck and cover anytime soon.

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HF Propagation And Earthquakes

For all the successes of modern weather forecasting, where hurricanes, blizzards, and even notoriously unpredictable tornadoes are routinely detected before they strike, reliably predicting one aspect of nature’s fury has eluded us: earthquakes. The development of plate tectonic theory in the middle of the 20th century and the construction of a worldwide network of seismic sensors gave geologists the tools to understand how earthquakes happened, and even provided the tantalizing possibility of an accurate predictor of a coming quake. Such efforts had only limited success, though, and enough false alarms that most efforts to predict earthquakes were abandoned by the late 1990s or so.

It may turn out that scientists were looking in the wrong place for a reliable predictor of coming earthquakes. Some geologists and geophysicists have become convinced that instead of watching the twitches and spasms of the earth, the state of the skies above might be more fruitful. And they’re using the propagation of radio waves from both space and the ground to prove their point that the ionosphere does some interesting things before and after an earthquake strikes.

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Hackaday Podcast 042: Capacitive Earthquakes, GRBL On ESP32, Solenoid Engines, And The TI-99 Space Program

Hackaday Editors Elliot Williams and Mike Szczys talk turkey on the latest hacks. Random numbers, art, and electronic geekery combine into an entropic masterpiece. We saw Bart Dring bring new life to a cool little multi-pen plotter from the Atari age. Researchers at UCSD built a very very very slow soft robot, and a broken retrocomputer got a good dose of the space age. A 555 is sensing earthquakes, there’s an electric motor that wants to drop into any vehicle, and did you know someone used to have to read the current time into the telephone ad nauseam?

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Direct download (59 MB)

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Simple Seismic Sensor Makes Earthquake Detection Personal

When an earthquake strikes, it’s usually hard to miss. At least that’s the case with the big ones; the dozens or hundreds of little quakes that go largely unnoticed every day are interesting too, and make sense to track. That’s usually left to the professionals, with racks of sensitive equipment and a far-flung network of seismic sensors. That doesn’t mean you can’t keep track of doings below your feet yourself, with something like this DIY seismograph.

Technically, what [Alex] built is better called a “seismic detector” since it’s not calibrated in any way. It’s just a simple sensor for detecting ground vibrations, whether they be due to passing trucks or The Big One. [Alex] lives in California, wedged between the Hayward, Calaveras, and San Andreas faults in San Jose, so there is plenty of opportunity for testing his device. The business end is a simple pendulum sensor, with a heavy metal bob hanging from a long wire inside a length of plastic pipe. Positioned close to the bob is a copper plate; the bob and the plate form an air-dielectric variable capacitor that controls the frequency of a simple 555 oscillator. The frequency is measured by a PIC microcontroller and sent to a Raspberry Pi, which displays the data on a graph. You can check in on real-time seismic activity in San Jose using the link above, or check out historical quakes, like the 7.1 magnitude Ridgecrest quake in July. [Alex]’s sensor is sensitive enough to pick up recent quakes in Peru, Fiji, and Nevada, and he even has some examples of visualizing the Earth’s core using data from the sensor. How cool is that?

We’ve seen other seismic detectors before, like this piezo-based device, or even one made from toilet parts. We like the simplicity of the capacitive sensor [Alex] used, though.

Watch Earthquake Roll Across A Continent In Seismograph Visualization Video

If your only exposure to seismologists at work is through film and television, you can be forgiven for thinking they still lay out rolls of paper to examine lines of ink under a magnifying glass. The reality is far more interesting in a field that has eagerly adopted all available technology. A dramatic demonstration of modern earthquake data gathering, processing, and visualization was Tweeted by @IRIS_EPO following a central California quake on July 4th, 2019. In this video can see the quake’s energy propagate across the continental United States in multiple waves of varying speed and intensity. The video is embedded below, but click through to the Twitter thread too as it has a lot more explanation.

The acronym IRIS EPO expands out to Incorporated Research Institutions for Seismology, Education and Public Outreach. We agree with their publicity mission; more people need to know how cool modern seismology is. By combining information from thousands of seismometers, we could see forces that we could not see from any individual location. IRIS makes seismic data available to researchers (or curious data science hackers) in a vast historical database or a real time data stream. Data compilations are presented in several different forms, this particular video is a GMV or Ground Motion Visualization. Significant events like the 4th of July earthquake get their own GMV page where we can see additional details, like the fact this visualization compiled data from 2,132 stations.

If this stirred up interest in seismology, you can join in the fun of networked seismic data. A simple seismograph can be built from quite humble components, but of course there are specially designed chips for the task as well.

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Earthquake Detection On A Chip

If you’ve ever been in an earthquake you’d assume it would be pretty easy to detect one. If things are shaking, there’s an earthquake. In reality, though, a lot of things can shake a sensitive instrument that is detecting shaking, so — for example — mechanical sensors will produce a lot of false positives. Now, however, you can filter out errant vibrations and reliably detect earthquakes on a chip.

The Rohm BP3901 has two primary features. First, it supposedly eliminates false detections due to things like a heavy truck rumbling by. In addition, while most sensors must be mounted completely flat, the BP3901 has a compensation method for angle which lets you mount it as much as 15 degrees rotated in either direction and still get good results. That’s because the BP3901 is based on the combination of an accelerometer and a microcontroller in one package to detect movement, characterize it based on an algorithm and reacting through an I2C bus and an INT pin.

Rohm suggests you could power the BP3901 for about 5 years with two AA batteries with the example of averaging 10 three-minute wake up events a month. We aren’t sure why we want to detect an earthquake, but we think we do. Imagine a large sensor network sending back real-time data as an earthquake happens — something we saw last year using Raspberry Pi. That project used a Geophone as the detector, which could be replaced by this chip. Rohm plans to have “OEM quantities” for sale next month which we hope means we can get smaller quantities from distributors.

A lot of people spend a lot of time thinking about how to predict earthquakes, as we’ve seen before. Of interest, the ancient Romans may have had a way to deflect earthquakes, so they probably didn’t care as much about detecting them.