Hacking The RF Protocol Of An Obscure Handheld Game

When you think old school handheld games, you probably imagine something like Nintendo’s Game Boy line or the Sega Game Gear. But outside of those now iconic systems, there was a vast subculture of oddball handheld games vying for a chunk of an adolescent’s weekly allowance. Many of these were legitimately terrible and frankly aren’t worth remembering, but a few offered unique features that were arguably ahead of their time.

One such game was Hasbro’s short-lived P-O-X. As explained by [Zachary Ennenga], the game didn’t spend much time on store shelves as its core concept of defeating undetectable alien invaders hell-bent on destroying our way of life proved to be more than a little problematic when it launched in September of 2001. But that doesn’t mean it didn’t have some cool ideas, such as a wireless ad-hoc multiplayer capability that let your game autonomously battle it out with other units that got close by.

Fascinated by this feature since his youth, [Zach] set out to study how this relatively cheap kid’s toy was able to pull this off back when even the flagship handheld consoles were still using physical link cables for multiplayer. He was aided in his quest by a particularly helpful patent, which not only gave him clues as to the frequency, data rate, modulation, and encoding of the RF signal, but even explained the game’s logic and overall structure. A lot of what was in the document seemed wishful thinking on the part of Hasbro, but reading through the marketing speak still uncovered some salient technical details.

A decoded P-O-X packet.

Armed with an RTL-SDR, GNU Radio, Inspectrum, and a bit of Python, [Zach] was able to identify the signal and begin the process of decoding it. This is where things get really interesting, as the details of his reverse engineering process are widely applicable for all sorts of unknown RF signals. Even if you’re like most people and have nearly zero interest in failed handheld games of the early 2000s, it’s well worth a read. The same techniques he uses to figure out the name and physical characteristics of the invisible foe his game is transmitting could one day help you figure out how to manipulate the data from that wireless weather station you’ve got in the backyard.

Once he figured out the major parts of the protocol, [Zach] moves on to creating his own packets and broadcasting them out in such a way that the real hardware will recognize it. He even comes up with some code that will automatically battle games which wander within range of his Yardstick One, which may come in handy during the inevitable P-O-X Renaissance.

While this might seem like a lot of effort to put into a game that most people have never even heard of, we’ll remind you that some of the greatest hacks to ever grace these pages have been born of similar pursuits. Even if you’re the only person in the world to directly benefit from your current line of research and experimentation, there’s still plenty of like-minded folks in this community that are all to happy to cheer you on from the sidelines.

GNU Radio Decodes Voyager Data

With the 44th anniversary of the launch of Voyager I, [Daniel] decided to use GNU Radio to decode Voyager data. The data isn’t live, but a recording from the Green Bank Telescope. The 16 GB file is in GUPPI format which stores raw IQ samples.

The file contains 64 frequency channels of just under 3MHz each. The signal of interest is in one channel, so it is easy to just throw away the rest of the data.

Continue reading “GNU Radio Decodes Voyager Data”

The Raspberry Pi Pico As An SDR Receiver

With the profusion of cheap RTL-SDR devices and the ever-reducing prices of more capable SDRs there might seem to be little place left for the low-bandwidth devices we’d have been happy with a decade or more ago, but there’s still plenty to be learned from something so simple. It’s something [Luigi Cruz] shows us with a simple SDR using the analogue-to-digital capabilities of the Raspberry Pi Pico, and since it works with GNU Radio we think it’s rather a neat project. CNX Software have the full story, and and quickly reveal that with its 500k samples per second bandwidth it’s not a machine that will set the SDR world on fire even when pushing Nyquist’s Law to the limit.

So with the exception of time signals and a few Long Wave broadcast stations if you live somewhere that still has them, you’ll need a fliter and receive converter to pull in anything of much use radio-wise with this SDR. But a baseband SDR with a couple of hundred kHz useful bandwidth and easy hackability through GNU Radio for the trifling cost of a Raspberry Pi Pico has to be worth a second look. You can see it in action in the video below the break, and if you’re at a loss for what to do with it take a look at Michael Ossmann and Kate Temkin’s 2019 Superconference talk.

Continue reading “The Raspberry Pi Pico As An SDR Receiver”

A Few Of My Favorite Things: Amateur Radio

Hackaday has among its staff a significant number of writers who also hold amateur radio licenses. We’re hardware folks at heart, so we like our radios homebrew, and we’re never happier than when we’re working at high frequencies.

Amateur radio is a multi-faceted hobby, there’s just so much that’s incredibly interesting about it. It’s a shame then that as a community we sometimes get bogged down with negativity when debating the minutia. So today let’s talk about a few of my favourite things about the hobby of amateur radio. I hope that you’ll find them interesting and entertaining, and in turn share your own favorite things in the comments below.

Continue reading “A Few Of My Favorite Things: Amateur Radio”

Learning SDR And DSP Hack Chat

Join us on Wednesday, November 11th at noon Pacific for Learning SDR and DSP Hack Chat with Marc Lichtman!

“Revolution” is a term thrown about with a lot less care than it probably should be, especially in fields like electronics. It’s understandable, though — the changes to society that have resulted from the “Transistor Revolution” or the “PC Revolution” or more recently, the “AI Revolution” have been transformative, often for good and sometimes for ill. The common thread, though, is that once these revolutions came about, nothing was ever the same afterward.

Such is the case with software-defined radio (SDR) and digital signal processing (DSP). These two related fields may not seem as transformative as some of the other electronic revolutions, but when you think about it, they really have transformed the world of radio communications. SDR means that complex radio transmitters and receivers, no longer have to be implemented strictly in hardware as a collection of filters, mixers, detectors, and amplifiers; instead, they can be reduced to a series of algorithms running on a computer.

Teamed with DSP, SDR has resulted in massive shifts in the RF field, with powerful, high-bandwidth radio links being built into devices almost as an afterthought. But the concepts can be difficult to wrap one’s head around, at least when digging beyond the basics and really trying to learn how SDR and DSP work. Thankfully, Dr. Marc Lichtman, an Adjunct Professor at the University of Maryland, literally wrote the book on the subject. “PySDR: A Guide to SDR and DSP using Python” is a fantastic introduction to SDR and DSP that’s geared toward those looking to learn how to put SDR and DSP to work in practical systems. Dr. Lichtman will stop by the Hack Chat to talk about his textbook, to answer your questions on how best to learn about SDR and DSP, and to discuss what the next steps are once you conquer the basics.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, November 11 at 12:00 PM Pacific time. If time zones baffle you as much as us, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

[Banner image credit: Dsimic, CC BY-SA 4.0, via Wikimedia Commons]

Continue reading “Learning SDR And DSP Hack Chat”

Software Defined Radio Academy Goes Virtual

They say every cloud has a silver lining. It’s hard to find a positive among all the bad news about the current global pandemic, but it has pushed more conferences and events to allow online participation either live or after the fact. A case in point: The Software Defined Radio Academy’s annual event is all on a YouTube channel so you can attend virtually.

Not all the videos are there yet, but the keynote along with some very technical talks about techniques ranging from FPGAs to spectrum monitoring and spectral correlation density — you can see that video, below. We presume you’ll eventually be able to watch all the presentations listed in the program.

Continue reading “Software Defined Radio Academy Goes Virtual”

Pulling Data From News Feed Telemetry

We are used to seeing shots from TV news helicopters every day, they are part of the backdrop to life in the 21st century. But so often we hear them overlaid with studio commentary, so it’s interesting to hear that their raw audio contains telemetry. It caught the attention of [proto17], who took some audio pulled from a news helicopter video and subjected it to a thorough investigation to retrieve the data.

The write-up is at a very in-depth level, and while there’s an admission that some of the steps could have been performed more easily with ready-made tools, its point is to go through all steps at a low level. So the action largely takes place in GNU Radio, in which we see the process of identifying the signal and shifting it downwards in frequency before deducing its baud rate to retrieve its contents. The story’s not over though, because we then delve into some ASCII tricks to identify the packet frames, before finally retrieving the data itself. It still doesn’t tell you what the data contains, but it’s a fascinating process getting there nonetheless.

It’s easy to forget that GNU Radio has signal processing capabilities far beyond radio, but it was the subject of a fascinating Superconference talk. We even jumped on the bandwagon in the non-foolish part of our April Fool this year.