Using Sonar To Measure Traffic Speeds

June 19, 2023 by 21 Comments

One of the most common ways of measuring the speed of a vehicle is by using radar, which typically involves generating radio waves, directing them at a moving vehicle, and measuring the various ways that they return to the device. This is a tried-and-true method, but can be expensive and technically complex. [GeeDub] wanted an easier way of measuring vehicles passing by his home, so he switched to using sonar instead to measure speeds based on the sounds the cars generate themselves.

The method he is using is similar to passive sonar in submarines, which can locate objects underwater based on the sounds they produce. After a false start attempting to measure Doppler shift, he switched to time correlation using two microphones, essentially using stereo audio input to detect subtle differences in arrival times of various sounds to detect the positions of passing vehicles. Doing this fast enough and extrapolating the data gathered, speed information can be calculated. For the data gathering and calculation, [GeeDub] is using a Raspberry Pi to help keep costs down, and some further configuration of the microphones and their power supplies were also needed to ensure quality audio was gathered.

With the system in place in a window, it detected around 9,000 vehicles over a three-day period. The software generates a normal distribution of vehicle speeds for this time, with the distribution centered on around 35 MPH, slightly above the posted speed limit of 30. As long as there’s a clear line of sight to the road using this system it’s just as effective as some other passive systems we’ve seen to measure vehicle speed. Of course, active speed measurement systems are not out of the realm of possibility if you’re willing to spend a little more.

Teardown Of An Aircraft Video Symbol Generator

June 19, 2023 by 17 Comments

[Adrian Smith] recently scored an avionics module taken from a British Aerospace 146 airliner and ripped it open for our viewing pleasure. This particular aircraft was designed in the early 1980s when the electronics used to feed the various displays in the cockpit were very different from modern designs. This particular box is called a ‘symbol generator’ and is used to generate the various real-time video feeds that are sent to the cockpit display units. Various instruments, for example, the weather radar, feed into it, and it then reformats the video if needed, mixing in any required additional display.

Top view of the symbol generator instrument rack

There are many gold-plated chips on these boards, which indicates these may be radiation-hardened versions of familiar devices, most of which are 54xx series logic. 54xx series logic is essentially the same functionally as the corresponding 74xx series, except for the much wider operating temperature range mandated by military and, by extension, commercial aviation needs. The main CPU board appears to be based around the Intel 8086, with some Zilog Z180 compatible processors used on the two video display controller boards. We noted the Zilog Z0853604, which is their counter/timer/GPIO chip. Obviously, there are many custom ASICs produced by Honeywell as well as other special order items that you’ll never find the datasheet for. Now there’s a challenge!

Finally, we note the standard 400 Hz avionics-standard power supply, which, as some may know, is the standard operating frequency for the AC power system used within modern aircraft systems. The higher frequency (compared to 50 or 60 Hz) means the magnetic components can be physically smaller and, therefore, lighter for a given power handling capability.

We see a lot of avionics teardowns, likely because they’re fascinating. Here’s some more British military gear, an interesting RF distance measuring box from the 1970s, and finally, some brave soul building their own avionics gear. What could possibly go wrong?

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A blue PCB remote control

The Remoteduino Nano Is A Tiny IR Remote That’s Truly Universal

June 18, 2023 by 13 Comments

Universal remotes are extremely convenient if they work correctly. But setting them up can be quite a hassle: often, you need to browse through long lists of TV models, key in the codes on the remote with just a blinking LED as confirmation, and then pray that the manufacturer included the correct codes for all your equipment. IR isn’t a very complicated technology, however, so it’s perfectly possible to roll your own universal remote, as [sjm4306] shows in his latest project, the Remoteduino Nano. It’s a fully programmable IR remote that gives you maximum flexibility when emulating the codes for those obscure A/V systems scattered around your home.

The remote runs on an ATmega328p in a tiny QFN package, which drives a standard 5 mm IR LED through a transistor. Eight buttons are available to the user, which can be freely mapped to any desired code. A five-pin header is included to program the ATmega through its serial port. However, this was mainly done to help debug – a user who only needs to program the device once would typically use a pogo-pin-based adapter instead.

Currently, codes can only be programmed through the serial port, but there’s also an IR receiver present that can be used to copy codes from an existing remote. [sjm4306] hasn’t implemented this feature in software yet, but will probably do so in a future update of the project’s Arduino sketch. If you’re impatient, you can also have a go at it yourself since all code and the board’s Gerber files are freely available for download.

Its tiny size makes the Remoteduino Nano a convenient tool to keep in your drawer if you like to tinker with A/V systems and keep losing those remotes. The Nano is actually an improved version of the original Remoteduino project that [sjm4306] developed a couple of years ago. The problem of a truly universal remote is one that dates back several decades, however.

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Too Much Git? Try Gitless

June 18, 2023 by 48 Comments

Git has been a powerful tool for software development and version control since the mid ’00s, gaining widespread popularity since then. Originally built by none other than Linus Torvalds for handling Linux kernel development, it’s branched out for use with all kinds of other projects. That being said, it is not the easiest thing to learn how to use, with tons of options, abstract ideas, and non-linear workflows to keep track of. So if you’re new to the system or don’t need all of its vast swath of features, you might want to try out an alternative like Gitless.

Thanks to the fact that the original Git is open source, it’s free to modify and use as any user sees fit, and there are plenty of options available. This one aims to simplify many of the features found in the original Git, implementing a tracking system which somewhat automates commits. It also includes a simplified branching system, making it easier to switch between branches and keep better track of all that’s happening in a project. The command line interface is simplified as well, and the entire system is backwards-compatible with Git which means that if you find yourself needing some of the more advanced tools it’s possible to switch between them with relative ease.

For those of us keeping track of our own software projects, who don’t necessarily need the full feature set that the original Git has to offer, this could be a powerful tool that decreases the steep learning curve that Git is known for. It’s definitely a system work diving into, though, regardless of whichever implementation you choose. It’s an effective tool for everything from complex, professional projects to small hobby projects on the Arduino.

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Hackaday Links: June 18, 2023

June 18, 2023 by 19 Comments

Will it or won’t it? That’s the question much on the minds of astronomers, astrophysicists, and the astro-adjacent this week as Betelgeuse continued its pattern of mysterious behavior that might portend a supernova sometime soon. You’ll recall that the red giant star in the constellation Orion went through a “great dimming” event back in 2019, where its brightness dipped to 60% of its normal intensity. That was taken as a sign that perhaps the star was getting ready to explode — or rather, that the light from whatever happened to the star 548 years ago finally reached us — and was much anticipated by skywatchers, yours truly included. As it turned out, the dimming was likely caused by Betelgeuse belching forth an immense plume of dust, temporarily obscuring our view of its light. Disappointing.

Those who gave up on the hope of seeing a supernova might have done so too fast, though, because now, the star seems to be swinging the other way and brightening. It briefly became the brightest star in Orion, nearly outshining nearby Sirius, the brightest star in the sky. So what does all this on-again, off-again business mean? According to Dr. Becky, a new study — not yet peer-reviewed, so proceed with caution — suggests that the star could go supernova in the next few decades. The evidence for this is completely unrelated to the great dimming event, but by analyzing the star’s long history of variable brightness. The data suggest that Betelgeuse has entered the carbon fusion phase of its life, a period that only lasts on the scale of a hundred years for a star that size. So we could be in for the ultimate fireworks show, which would leave us with a star brighter than the full moon that’s visible even in daylight. And who doesn’t want to see something like that?

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Better Antennas Via Annealing (Simulated)

June 18, 2023 by 26 Comments

If you want to simulate a tic-tac-toe game, that’s easy. You can evaluate every possible move in a reasonable amount of time. Simulating antennas, however, is much harder. [Rosrislav] has been experimenting with using simulated annealing to iterate antenna designs, and he shares his progress in a recent blog post.

For many problems, it simply isn’t possible to try all possible inputs to determine what provides the “best” result. Instead of trying every single input or set of inputs, you can try random ones and discard all but the best guesses. Then you make small changes and try again. The only problem is that the algorithm may lock in on a “local maximum” — that is, a relatively high value that isn’t the highest because it forms a peak that isn’t the highest peak. Or, if you are looking for a minimum, you may lock on to a local minimum — same thing.

To combat that, simulated annealing works like annealing a metal. The simulation employs a temperature that cools over time. The higher the temperature, the more likely large changes to the input are to occur.

The Python program uses the PyNEC package to provide simulation. The program sets up random antenna lengths and finds the projected gain, attempting to optimize for maximum gain.

The post is long on code and short on details, so you will probably want to read the Python source to see exactly what it is doing. But it could probably serve as a template to do other simulated annealing simulations for other antennas or anything you had a simulation engine to evaluate.

Several techniques allow you to optimize things that are too hard to search exhaustively, and we’ve talked about simulated annealing and genetic algorithms before. However, lately, we’ve been more interested in annealing 3D prints.