Where’s That Radio? A Brief History Of Direction Finding

August 19, 2021 by Al Williams 35 Comments

We think of radio navigation and direction finding as something fairly modern. However, it might surprise you that direction finding is nearly as old as radio itself. In 1888, Heinrich Hertz noted that signals were strongest when in one orientation of a loop antenna and weakest 90 degrees rotated. By 1900, experimenters noted dipoles exhibit similar behavior and it wasn’t long before antennas were made to rotate to either maximize signal or locate the transmitter.

British radio direction finding truck from 1927; public domain

Of course, there is one problem. You can’t actually tell which side of the antenna is pointing to the signal with a loop or a dipole. So if the antenna is pointing north, the signal might be to the north but it could also be to the south. Still, in some cases that’s enough information.

John Stone patented a system like this in 1901. Well-known radio experimenter Lee De Forest also had a novel system in 1904. These systems all suffered from a variety of issues. At shortwave frequencies, multipath propagation can confuse the receiver and while longwave signals need very large antennas. Most of the antennas moved, but some — like one by Marconi — used multiple elements and a switch.

However, there are special cases where these limitations are acceptable. For example, when Pan Am needed to navigate airplanes over the ocean in the 1930s, Hugo Leuteritz who had worked at RCA before Pan Am, used a loop antenna at the airport to locate a transmitter on the plane. Since you knew which side of the antenna the airplane must be on, the bidirectional detection wasn’t a problem.

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Airdropping Live Fish Is A Thing And It Looks Magnificent

August 18, 2021 by Lewin Day 52 Comments

Utah is a place that features a wonderful and varied wilderness. Its mountainous terrain is home to many valleys, ponds, and streams. They’re a particular favorite of recreational anglers who visit the region for the great fishing. Oftentimes, however, these areas are fished out by visitors and need to be restocked. Other environmental factors also come into play in reducing populations, too.

A plane delivering live fish to the lakes of Utah via air drop. Source: Utah DWR

When this happens in some areas, it’s as simple as driving up a truck full of water and fish and dumping them into the lake. The problem is that many of these lakes and streams are difficult to access by foot or by road. Believe it or not, the most practical method found to deal with the problem thus far is dropping in live fish by air. Here’s how it all goes down.

Live Cargo

Typically, the fish dropped into these remote watercourses are quite young, and on the order of 1-3″ long. The fish are specifically raised to later be fished, and are also usually sterile, making it easier for Utah’s Division of Wildlife Resources to manage numbers. When it comes time to restock remote lakes, waterbombing planes are pumped full of water and loaded up with fish.

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Valve Sells Software, So What’s With All The Hardware?

August 16, 2021 by Drew Littrell 47 Comments

Steam branding is strong. Valve Corporation has turned their third-party marketplace into the first place millions choose to buy their PC games. The service has seen record-breaking numbers earlier this year with over 25 million concurrent users, so whatever they are doing is clearly working. Yet with all those software sales, last month Valve announced a new piece of hardware they call the Steam Deck.

Use the colloquialism you’d like, “not resting on your laurels” or “Mamba Mentality”, it’s not as if competitors in the handheld PC space are boasting ludicrous sales numbers. At their core, Valve is in the business of selling computer games. So why venture into making hardware? Continue reading “Valve Sells Software, So What’s With All The Hardware?” →

Figuring Out Earth’s Past Climate Through Paleoclimatology And Its Lessons For Today

August 11, 2021 by Maya Posch 28 Comments

Roughly 4.6 billion years ago, Earth would gain its first atmosphere, yet this was an atmosphere that was completely unlike the atmosphere we know today. Today’s oxygen-rich atmosphere we’re familiar with didn’t form until the Proterozoic, between 2,500 and 541 million years ago, when oxygen-producing bacteria killed off much of the previously thriving life from the preceding Archean.

This, along with studies of massive insects such as the 75 cm wingspan Meganeuropsis permiana dragonflies from the Permian, and reconstructed temperature, oxygen, and carbon dioxide levels via paleoclimatology show periods during which Earth’s atmosphere and accompanying climate would be unrecognizable to us humans.

Human history covers only a minuscule fraction of Earth’s history during arguably one of the latter’s coolest, least eventful periods, and yet anthropogenic (man-made) climate change now threatens to rapidly change this. But wait, how do we know what the climate was like over such vast time scales? Let’s take a look into how we managed to reconstruct the Earth’s ancient climate, and what these findings mean for our prospects as a species today.

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Fresh Paint Or Patina Of Ages, That’s The Antique Question

July 30, 2021 by Jenny List 46 Comments

The world of antique furniture and the world of hackers rarely coincide, and perhaps the allure of the latest tech is greater for most of us than that of a Chipendale cabinet. But there are times when there are analagous situations in both worlds, so it’s worth taking a moment to consider something.

This late-17th-century dressing box would not be of such value or interest were a restoration to strip it of its patina. Daderot, CC0.

Antique furniture has survived for hundreds of years before being owned by today’s collectors. Along the way it picks up bumps and scrapes, wear, and even the occasional repair. Valuable pieces turn up all the time, having been discovered in dusty attics, cowsheds, basements, and all sorts of places where they may have been misused in ways that might horrify those who later pay big money for them. Thus there is a whole industry of craft workers in the field of furniture restoration whose speciality lies in turning the wreck of a piece of furniture into a valuable antique for the showroom.

The parallel in our community if you hadn’t already guessed, can be found in the world of retrocomputers. They are the antiques we prize, they come to us after being abused by kids and then left to languish in a box of junk somewhere. Their capacitors are leaking, their cases may be cracked or dirty, and they often possess the signature look of old ABS mouldings, their characteristic yellowing. This is caused by the gradual release of small quantities of bromine as the fire retardant contained within the plastic degrades under UV light, and causes considerable consternation among some retrocomputing enthusiasts. Considerable effort goes into mitigating it, with the favourite technique involving so-called Retr0bright recipes that use hydrogen peroxide to bleach away the colour.

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Avoiding Repetitive Stress Injury: Invest In Yourself Now, Or Pay Later

July 22, 2021 by Kristina Panos 49 Comments

There I was, thirty years after I first sat down at an Apple IIe , and I suddenly found myself wondering if I would ever use a computer again without pain. How could I work if I couldn’t use a computer anymore? I had to seriously ask myself this question. It took a bit of a winding road to figure out what was going on and two EMGs to confirm it, but after all these years, it was clear to the medical community that I had developed a repetitive stress injury (RSI) called cubital tunnel syndrome in my left arm.

Yeah, it’s about like that. Image via Kinesis

Cubital tunnel syndrome is like carpal tunnel, but in your elbow instead of your wrist. What a misnomer! Sometimes my pain went all the way from my armpit to my fingertips and made me want to gnaw my own arm off. I don’t think you can really understand neuropathy unless you’ve felt this weird, annoying type of pain firsthand. I hope you never do.

Can you stop and seriously imagine not being able to use a computer for the rest of your life? Or at least feeling that way because doing so causes incredibly annoying pain? I feel like we’re all vaguely aware of the standard list of anti-RSI precautions, but let’s review:

maintain good posture — sit with feet flat on the floor, wrists straight, elbows at 90°
put the screen an arm’s length away at eye level
take frequent short breaks

Yes, those are all fine and good. But there are other things you can do to avoid computer-related RSIs, like using ergonomic inputs, and building a custom setup that fits you exactly. This isn’t a study kiosk at the university library we’re talking about — this is your battlestation! The problem is that many people are stubborn, and won’t go out of their way to do anything to proactively prevent these injuries. But you don’t have to cross a bridge when you come to it if you have a map that shows you a way around the body of water.

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What Exactly Is A Gaussian Blur?

July 21, 2021 by Lewin Day 29 Comments

Blurring is a commonly used visual effect when digitally editing photos and videos. One of the most common blurs used in these fields is the Gaussian blur. You may have used this tool thousands of times without ever giving it greater thought. After all, it does a nice job and does indeed make things blurrier.

Of course, we often like to dig deeper here at Hackaday, so here’s our crash course on what’s going on when you run a Gaussian blur operation. Continue reading “What Exactly Is A Gaussian Blur?” →