Hackaday Links: November 15, 2020

November 15, 2020 by Dan Maloney 13 Comments

Now that we drive around cars that are more like mobile data centers than simple transportation, there’s a wealth of data to be harvested when the inevitable crashes occur. After a recent Tesla crash on a California highway, a security researcher got a hold of the car’s “black box” and extracted some terrifying insights into just how bad a car crash can be. The interesting bit is the view of the crash from the Tesla’s forward-facing cameras with object detection overlays. Putting aside the fact that the driver of this car was accelerating up to the moment it rear-ended the hapless Honda with a closing speed of 63 MPH (101 km/h), the update speeds on the bounding boxes and lane sensing are incredible. The author of the article uses this as an object lesson in why Level 2 self-driving is a bad idea, and while I agree with that premise, the fact that self-driving had been disabled 40 seconds before the driver plowed into the Honda seems to make that argument moot. Tech or not, someone this unskilled or impaired was going to have an accident eventually, and it was just bad luck for the other driver.

Last week I shared a link to Scan the World, an effort to 3D-scan and preserve culturally significant artifacts and create a virtual museum. Shortly after the article ran we got an email from Elisa at Scan the World announcing their “Unlocking Lockdown” competition, which encourages people to scan cultural artifacts and treasures directly from their home. You may not have a Ming Dynasty vase or a Grecian urn on display in your parlor, but you’ve probably got family heirlooms, knick-knacks, and other tchotchkes that should be preserved. Take a look around and scan something for posterity. And I want to thank Elisa for the link to the Pompeiian bread that I mentioned.

The Defense Advanced Research Projects Agency (DARPA)has been running an interesting challenge for the last couple of years: The Subterranean (SubT) Challenge. The goal is to discover new ways to operate autonomously below the surface of the Earth, whether for mining, search and rescue, or warfare applications. They’ve been running different circuits to simulate various underground environments, with the most recent circuit being a cave course back in October. On Tuesday November 17, DARPA will webcast the competition, which features 16 teams and their autonomous search for artifacts in a virtual cave. It could make for interesting viewing.

If underground adventures don’t do it for you, how about going upstairs? LeoLabs, a California-based company that specializes in providing information about satellites, has a fascinating visualization of the planet’s satellite constellation. It’s sort of Google Earth but with the details focused on low-earth orbit. You can fly around the planet and watch the satellites whiz by or even pick out the hundreds of spent upper-stage rockets still up there. You can lock onto a specific satellite, watch for near-misses, or even turn on a layer for space debris, which honestly just turns the display into a purple miasma of orbiting junk. The best bit, though, is the easily discerned samba-lines of newly launched Starlink satellites.

A doorbell used to be a pretty simple device, but like many things, they’ve taken on added complexity. And danger, it appears, as Amazon Ring doorbell users are reporting their new gadgets going up in flame upon installation. The problem stems from installers confusing the screws supplied with the unit. The longer wood screws are intended to mount the device to the wall, while a shorter security screw secures the battery cover. Mix the two up for whatever reason, and the sharp point of the mounting screw can find the LiPo battery within, with predictable results.

And finally, it may be the shittiest of shitty robots: a monstrous robotic wolf intended to scare away wild bears. It seems the Japanese town of Takikawa has been having a problem with bears lately, so they deployed a pair of these improbable looking creatures to protect themselves. It’s hard to say what’s the best feature: the flashing LED eyes, the strobe light tail, the fact that the whole thing floats in the air atop a pole. Whatever it is, it seems to work on bears, which is probably good enough. Take a look in the video below the break.

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What Is Worth Saving?

November 14, 2020 by Elliot Williams 72 Comments

When it rain, it pours. One of the primary support cables holding up the Arecibo Observatory dish in Puerto Rico has just snapped, leaving its already uncertain fate. It had been badly damaged by Hurricane Maria in 2017, and after a few years of fundraising, the repairs were just about to begin on fixing up that damage, when the cable broke. Because the remaining cables are now holding increased weight, humans aren’t allowed to work on the dome until the risk of catastrophic failure has been ruled out — they’re doing inspection by drone.

Arecibo Observatory has had quite a run. It started out life as part of a Cold War era ICBM-tracking radar, which explains why it can transmit as well as receive. And it was the largest transmitting dish the world had. It was used in SETI, provided the first clues of gravitational waves, and found the first repeating fast radio bursts. Its radar capabilities mean that it could be used in asteroid detection. There are a number of reasons, not the least of which its historic import, to keep it running.

So when we ran this story, many commenters, fearing the worst, wrote in with their condolences. But some wrote in with outrage at the possibility that it might not be repaired. The usual suspects popped up: failure to spend enough on science, or on infrastructure. From the sidelines, however, and probably until further structural studies are done, we have no idea how much a repair of Arecibo will cost. After that, we have to decide if it’s worth it.

Per a 2018 grant, the NSF was splitting the $20 M repair and maintenance bill with a consortium led by the University of Central Florida that will administer the site. With further damage, that might be an underestimate, but we don’t know how much of one yet.

When do you decide to pull the plug on something like this? Although the biggest, Arecibo isn’t the only transmitter out there. The next largest transmitters are part of Deep Space Network, though, and are busy keeping touch with spacecraft all around our solar system. For pure receiving, China’s FAST is bigger and better. And certainly, we’ve learned a lot about radio telescopes since Arecibo was designed.

I’m not saying that we won’t shed a tear if Arecibo doesn’t get repaired, but it’s not the case that the NSF’s budget has been hit dramatically, or that they’re unaware of the comparative value of various big-ticket astronomy projects. Without being in their shoes, and having read through the thousands of competing grant proposals, it’s hard to say that the money spent to prop up a 70 year old telescope wouldn’t be better spent on something else.

DSP Spreadsheet: The Goertzel Algorithm Is Fourier’s Simpler Cousin

November 13, 2020 by Al Williams 30 Comments

You probably have at least a nodding familiarity with the Fourier transform, a mathematical process for transforming a time-domain signal into a frequency domain signal. In particular, for computers, we don’t really have a nice equation so we use the discrete version of the transform which takes a series of measurements at regular intervals. If you need to understand the entire frequency spectrum of a signal or you want to filter portions of the signal, this is definitely the tool for the job. However, sometimes it is more than you need.

For example, consider tuning a guitar string. You only need to know if one frequency is present or if it isn’t. If you are decoding TouchTones, you only need to know if two of eight frequencies are present. You don’t care about anything else.

A Fourier transform can do either of those jobs. But if you go that route you are going to do a lot of math to compute things you don’t care about just so you can pick out the one or two pieces you do care about. That’s the idea behind the Goertzel. It is essentially a fast Fourier transform algorithm stripped down to compute just one frequency band of interest. The math is much easier and you can usually implement it faster and smaller than a full transform, even on small CPUs.

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Hackaday Podcast 093: Hot And Fast Raspberry Pi, Dr. Seuss Drone, M&M Mass Meter, And FPGA Tape Backup

November 13, 2020 by Mike Szczys No comments

Hackaday editors Mike Szczys and Elliot Williams wrangle the epic hacks that crossed our screens this week. Elliot ran deep on overclocking all three flavors of the Raspberry Pi 4 this week and discovered that heat sinks rule the day. Mike exposes his deep love of candy-coated chocolates while drooling over a machine that can detect when the legume is missing from a peanut M&M. Core memory is so much more fun when LEDs come to play, one tiny wheel is the power-saving secret for a very strange multirotor drone, and there’s more value in audio cassette data transfer than you might think — let this FPGA show you how it’s done.

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 (~70 MB)

Places to follow Hackaday podcasts:

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This Week In Security: Platypus, Git.bat, TCL TVs, And Lessons From Online Gaming

November 13, 2020 by Jonathan Bennett 9 Comments

Git’s Large File System is a reasonable solution to a bit of a niche problem. How do you handle large binary files that need to go into a git repository? It might be pictures or video that is part of a project’s documentation, or even a demonstration dataset. Git-lfs’s solution is to replace the binary files with a text-based pointer to where the real file is hosted. That’s not important to understanding this vulnerability, though. The problem is that git-lfs will call the main git binary as part of its operation, and when it does so, the full path is not used. On a Unix system, that’s not a problem. The $PATH variable is used to determine where to look for binaries. When git is run, /usr/bin/git is automagically run. On a Windows system, however, executing a binary name without a path will first look in the current directory, and if a matching executable file is not found, only then will the standard locations be checked.

You may already see the problem. If a repository contains a git.exe, git.bat, or another git.* file that Windows thinks is executable, git-lfs will execute that file instead of the intended git binary. This means simply checking out a malicious repository gets you immediate code execution. A standard install of git for Windows, prior to 2.29.2.2, contains the vulnerable plugin by default, so go check that you’re updated!

Then remember that there’s one more wrinkle to this vulnerability. How closely do you check the contents of a git download before you run the next git command? Even with a patched git-lfs version, if you clone a malicious repository, then run any other git command, you still run the local git.* file. The real solution is pushing the local directory higher up the path chain. Continue reading “This Week In Security: Platypus, Git.bat, TCL TVs, And Lessons From Online Gaming” →

Tech Hidden In Plain Sight: Gas Pumps

November 12, 2020 by Al Williams 67 Comments

Ask someone who isn’t technically inclined how a TV signal works or how a cell phone works, or even how a two-way switch in a hall light works and you are likely to get either a blank stare or a wildly improbable explanation. But there are some things so commonplace that even the most tech-savvy of us don’t bother thinking about. One of these things is the lowly gas pump.

Gas pumps are everywhere and it’s a safe bet to assume everyone reading this has used one at some point, most of use on a regular basis. But what’s really going on there?

Most of it is pretty easy to figure out. As the name implies, there must be a pump. There’s some way to tell how much is pumping and how much it costs and, today, some way to take the payment. But what about the automatic shut off? It isn’t done with some fancy electronics, that mechanism dates back decades. Plus, we’re talking about highly combustible materials, there has to be more to it then just a big tank of gas and a pump. Safety is paramount and, experientially, we don’t hear about gas stations blowing up two or three times a day, so there must be some pretty stout safety features. Let’s pay homage to those silent safety features and explore the tricks of the gasoline trade.

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Spacing Out: A Big Anniversary, Starlink Failures Plummet, Lunar Cellphones, And A Crewed Launch

November 11, 2020 by Jenny List 32 Comments

After a couple of months away we’re returning with our periodic roundup of happenings in orbit, as we tear you away from Star Trek: Discovery and The Mandalorian, and bring you up to date with some highlights from the real world of space. We’ve got a launch to look forward to this week, as well as a significant anniversary.

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