Building A GPS Receiver From The Ground Up

One of the more interesting facets of GPS is that, at least from the receiver’s point-of-view, it’s a fairly passive system. All of the information beamed down from the satellites is out in the ether, all the time, free for anyone on the planet to receive and use as they see fit. Of course you need to go out and buy a receiver or, alternatively, possess a certain amount of knowledge to build a circuit that can take those signals and convert them into something usable. Luckily, [leaning_tower] has the required knowledge and demonstrates it with this DIY GPS receiver.

This receiver consists of five separate circuit boards, all performing their own function. The first, a mixer board, receives the signal via an active antenna and converts it to a lower frequency. From there it goes to a second mixer and correlation board to compare the signal to a local reference, then a signal processing board that looks at this intermediate frequency signal to make sense of the data its seeing. Finally, an FPGA interfacing board ties everything together and decodes the information into a usable form.

Dealing with weak signals like this has its own set of challenges, as [leaning_tower] found out. The crystal oscillator had to be decapped and modified to keep from interfering with the GPS radio since they operated on similar frequencies. Even after ironing out all the kinks, the circuit takes a little bit of time to lock on to a specific satellite but with a second GPS unit for checking and a few weeks of troubleshooting, the homebrew receiver is up and running. It’s an impressive and incredibly detailed piece of work which is usually the case with sensitive radio equipment like GPS. Here’s another one built on a Raspberry Pi with 12 channels and a pretty high accuracy.

It’s Pronounced GIF

As the holiday season is upon us and a Hackaday scribe sits protected from the incoming Atlantic storms in her snug eyrie, it’s time for her to consider the basics of her craft. Writing, spelling, and the English language; such matters as why Americans have different English spellings from Brits, but perhaps most important of them all for Hackaday readers; is it “gif”, or is is “jif”? This or the jokey sentence about spellings might be considered obvious clickbait, but instead they’re a handle to descend into the study of language. Just how do we decide the conventions of our language, and should we even care too much about them?

Don’t Believe Everything You Read in School

A picture of an American classroom in 1004
Not everything you learn here is worth holding on to. Harrison Keely, CC BY 4.0.

We are sent to school to Learn Stuff. During that time we are deprived of our liberty as a succession of adults attempt year after year to cram our heads with facts. Some of it we find interesting and other parts not so much, but for the majority of it, we are discouraged from thinking for ourselves and are instead expected to learn by rote a set of fixed curricula.

Thus while writers have to discover for themselves that English is a constantly evolving language through which they can break free of these artificial bounds that school has imposed upon them, far too many people remain afraid to put their head above the linguistic parapet.

The result is that perceived deviations from the rules are jumped upon by those afraid to move with the language, and we even find our own linguistic Holy Wars to fight. The one mentioned above about “gif” versus “jif” is a great example, does it really matter that much whether you pronounce it with a hard “G” because that’s how most people say it, or as though it were a “J” because the creator of the file format said it that way? Not really, because English is an evolving language in the hands of those who speak it, not those of the people who write school books. Continue reading “It’s Pronounced GIF”

Impressively Responsive Air Drums Built Using The Raspberry Pi Pico

Drum kits are excellent fun and a terrific way to learn a sense of rhythm. They’re also huge and unwieldy. In contrast, air drums can be altogether more compact, if lacking the same impact as the real thing. In any case, students [Ang], [Devin] and [Kaiyuan] decided to build a set of air drums themselves for their ECE 4760 microcontroller class at Cornell.

As per the current crop of ECE4760 projects, the build relies on the Raspberry Pi Pico microcontroller as the brains of the operation. The Pico is charged with reading the output of MPU6050 inertial measurement units mounted to a pair of drum sticks. The kick pedal itself simply uses a button instead.

Where the project gets really interesting, though, is in the sound synthesis. The build doesn’t simply play different pre-recorded samples for different drums. Instead, it uses the Karplus-Strong Drum Synthesis function combined with a wavetable to generate different sounds.

In the demo video, we get to hear the air drums in action, complete with a Stylophone playing melody. Unlike some toy versions that trigger seemingly at random with no rhythm, these air drums are remarkably responsive and sound great. They could be a great performance instrument if designed for the purpose.

We’ve seen similar builds before, too.

Continue reading “Impressively Responsive Air Drums Built Using The Raspberry Pi Pico”

2023: As The Hardware World Turns

We’ve made it through another trip around the sun, and for the first time in what feels like far too long, it seems like things went pretty well for the hackers and makers of the world. Like so many, our community suffered through a rough couple of years: from the part shortages that made building even the simplest of devices more expensive and difficult than it should have been, to the COVID-mandated social distancing that robbed us of our favorite meetups. But when looking back on the last twelve months, most of the news was refreshingly positive.

Pepperoni costs ten bucks, but they can’t activate Windows on their registers…

Oh sure, a trip to to the grocery store can lead to a minor existential crisis at the register, but there’s not much we at Hackaday can do about that other than recommend you some good hydroponics projects to help get your own home farm up and running.

As has become our New Year tradition, we like to take this time to go over some of the biggest stories and trends that we picked up on from our unique vantage point. Some will be obvious, but there’s always a few that sneak up on us. These posts tend to make for interesting reading in the future, and if you’ve got the time, we’d recommend going back and reading the previous entries in this series and reminiscing a bit.

It’s also a good time to reflect on Hackaday itself — how we’ve grown, the things that have changed, and perhaps what we can do better going forward. Believe it or not we do read all of the feedback from the community, whether it’s in the comments of individual posts or sent into us directly. We couldn’t do this without readers like you, so please drop us a line and let us know what you’re thinking.

So before we get any farther into 2024, let’s wind back the clock and revisit some of the highlights from the previous year.

Continue reading “2023: As The Hardware World Turns”

Air Hockey Table Embraces DOOM, Retro Gaming

[Chris Downing] recently finished up a major project that spanned some two years and used nearly every skill he possessed. The result? A smart air hockey table with retro-gaming roots. Does it play DOOM? It sure (kind of) does!

Two of the most striking features are the score board (with LCD screen and sound) and the play surface which is densely-populated with RGB LED lighting and capable of some pretty neat tricks. Together, they combine to deliver a few different modes of play, including a DOOM mode.

The first play mode is straight air hockey with automated score tracking and the usual horns and buzzers celebrating goals. The LED array within the table lights up to create the appearance and patterns of a typical hockey rink.

DOOM hockey mode casts one player as Demons and the other as the Doom Slayer, and the LED array comes to life to create a play surface of flickering flames. Screams indicate goals (either Demon screams or Slayer screams, depending on who scores!)

In retrogaming emulation mode, the tabletop mirrors the screen.

Since the whole thing is driven by a Raspberry Pi, the table is given a bit of gaming flexibility with Emulation Mode. This mode allows playing emulated retro games on the scoreboard screen, and as a super neat feature, the screen display is mirrored on the tabletop’s LED array. [Chris] asserts that the effect is imperfect, but to us it looks at least as legible as DOOM on 7-segment displays.

This project is a great example of how complex things can get when one combines so many different types of materials and fabrication methods into a single whole. The blog post has a lot of great photos and details, but check out the video (embedded below) for a demonstration of everything in action. Continue reading “Air Hockey Table Embraces DOOM, Retro Gaming”

An Animated LED Fireplace Powered By The CH32V003

Once you’ve mastered the near-magical ability of turning your ideas into a piece of hardware you can hold in your hand, it’s only natural that you’ll want to spread the joy. The holidays are a perfect time to produce a custom piece of electronics for friends and family, but there’s a catch: going from making one or two of something to making dozens of them can introduce some interesting challenges. Not only will you want to cost optimize your design, but to save yourself some aggravation, you’ll likely want to simplify the assembly process.

The fifty electronic fireplaces designed by built by [Adam Anderson], [Daniel Quach], and [Johan Wheeler] are a perfect example of both concepts, and while we’re coming across it a bit late for this year’s gift exchange, we wouldn’t be surprised if these MIT-licensed beauties end up under a few more trees in 2024.

Continue reading “An Animated LED Fireplace Powered By The CH32V003”

NHL 94 Sega Genesis ROM hack playing on LCD monitor.

NHL ’24 ROM Hack Reimagines Classic Game, Zamboni And All

Thirty years is a long time to keep a piece of software alive, but there aren’t many pieces of software like NHL ’94 for the Sega Genesis. Despite new annual iterations of publisher Electronic Arts’ NHL hockey video game some players never connected with it like quite like they did in 1994. For years now it’s been a tradition for members of the NHL ’94 forums to incorporate the hockey league’s current players into the Sega Genesis original, however, the work [Adam] contributed this season goes beyond a mere roster update. This NHL ’24 ROM hack is more like a complete overhaul. Everything that was old is new again. Continue reading NHL ’24 ROM Hack Reimagines Classic Game, Zamboni And All”