The Labor Of Love That Is Recovering Lost Software

September 13, 2021 by Chris Wilkinson 9 Comments

At the beginning of the home computer revolution, the humble compact cassette was far and away the most popular choice for microcomputer data storage, especially on the European continent. As a volunteer at the Museum of Computing, [Keith] was instrumental in recovering and archiving the early works of Roger Dymond, a pioneering developer of early computer software in the United Kingdom.

In his video, [Keith] goes to great lengths detailing the impact that Roger Dymond had on the early home computing scene. After being let go from his council apprenticeship, Roger turned his attention to developing games for the ZX81, and later the ZX Spectrum. With the help of his family, he went on to run a moderately successful mail-order games publishing venture for several years. Increasing advertising costs and a crowded development scene saw Roger’s business become nonviable by 1983, but not before developing several gambling-style games and a standout Space Invaders clone.

Fast forward to 2021, and while some of Roger’s Spectrum software had been archived, much had been marked as ‘missing’ by online archivists. After further research, [Keith] realized that another potentially important tape had been forgotten about. ‘Games Compendium’ for the ZX81 had been completely lost to time, with the only evidence that it had ever existed coming from a 1983 advert in ‘Sinclair User’ magazine. Being written for the earlier model ZX81, the compendium would undoubtedly be of interest to software archivists and game historians.

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Cable Modem Turned Spectrum Analyzer

August 27, 2021 by Bryan Cockfield 19 Comments

Hopefully by now most of us know better than to rent a modem from an internet service provider. Buying your own and using it is almost always an easy way to save some money, but even then these pieces of equipment won’t last forever. If you’re sitting on an older cable modem and thinking about tossing it in the garbage, there might be a way to repurpose it before it goes to the great workbench in the sky. [kc9umr] has a way of turning these devices into capable spectrum analyzers.

The spectrum analyzer feature is a crucial component of cable modems to help take advantage of the wide piece of spectrum that is available to them on the cable lines. With some of them it’s possible to access this feature directly by pointing a browser at it, but apparently some of them have a patch from the cable companies to limit access. By finding one that hasn’t had this patch applied it’s possible to access the spectrum analyzer, and once [kc9umr] attached some adapters and an antenna to his cable modem he was able to demonstrate it to great effect.

While it’s somewhat down to luck as to whether or not any given modem will grant access to this feature, for the ones that do it seems like a powerful and cheap tool. It’s agnostic to platform, so any computer on the network can access it easily, and compared to an RTL-SDR it has a wider range. There are some limitations, but for the price it can’t be beat which will cost under $50 in parts unless you happen to need two inputs like this analyzer .

Thanks to [Ezra] for the tip!

Speech Recognition On An Arduino Nano?

May 26, 2021 by Orlando Hoilett 24 Comments

Like most of us, [Peter] had a bit of extra time on his hands during quarantine and decided to take a look back at speech recognition technology in the 1970s. Quickly, he started thinking to himself, “Hmm…I wonder if I could do this with an Arduino Nano?” We’ve all probably had similar thoughts, but [Peter] really put his theory to the test.

The hardware itself is pretty straightforward. There is an Arduino Nano to run the speech recognition algorithm and a MAX9814 microphone amplifier to capture the voice commands. However, the beauty of [Peter’s] approach, lies in his software implementation. [Peter] has a bit of an interplay between a custom PC program he wrote and the Arduino Nano. The learning aspect of his algorithm is done on a PC, but the implementation is done in real-time on the Arduino Nano, a typical approach for really any machine learning algorithm deployed on a microcontroller. To capture sample audio commands, or utterances, [Peter] first had to optimize the Nano’s ADC so he could get sufficient sample rates for speech processing. Doing a bit of low-level programming, he achieved a sample rate of 9ksps, which is plenty fast for audio processing.

To analyze the utterances, he first divided each sample utterance into 50 ms segments. Think of dividing a single spoken word into its different syllables. Like analyzing the “se-” in “seven” separate from the “-ven.” 50 ms might be too long or too short to capture each syllable cleanly, but hopefully, that gives you a good mental picture of what [Peter’s] program is doing. He then calculated the energy of 5 different frequency bands, for every segment of every utterance. Normally that’s done using a Fourier transform, but the Nano doesn’t have enough processing power to compute the Fourier transform in real-time, so Peter tried a different approach. Instead, he implemented 5 sets of digital bandpass filters, allowing him to more easily compute the energy of the signal in each frequency band.

The energy of each frequency band for every segment is then sent to a PC where a custom-written program creates “templates” based on the sample utterances he generates. The crux of his algorithm is comparing how closely the energy of each frequency band for each utterance (and for each segment) is to the template. The PC program produces a .h file that can be compiled directly on the Nano. He uses the example of being able to recognize the numbers 0-9, but you could change those commands to “start” or “stop,” for example, if you would like to.

[Peter] admits that you can’t implement the type of speech recognition on an Arduino Nano that we’ve come to expect from those covert listening devices, but he mentions small, hands-free devices like a head-mounted multimeter could benefit from a single word or single phrase voice command. And maybe it could put your mind at ease knowing everything you say isn’t immediately getting beamed into the cloud and given to our AI overlords. Or maybe we’re all starting to get used to this. Whatever your position is on the current state of AI, hopefully, you’ve gained some inspiration for your next project.

Pi-Based Spectrometer Puts The Complexity In The Software

April 23, 2021 by Dan Maloney 43 Comments

Play around with optics long enough and sooner or later you’re probably going to want a spectrometer. Optical instruments are famously expensive, though, at least for high-quality units. But a useful spectrometer, like this DIY Raspberry Pi-based instrument, doesn’t necessarily have to break the bank.

This one comes to us by way of [Les Wright], whose homebrew laser builds we’ve been admiring for a while now. [Les] managed to keep the costs to a minimum here by keeping the optics super simple. The front end of the instrument is just a handheld diffraction-grating spectroscope, of the kind used in physics classrooms to demonstrate the spectral characteristics of different light sources. Turning it from a spectroscope to a spectrometer required a Raspberry Pi and a camera; mounted to a lens and positioned to see the spectrum created by the diffraction grating, the camera sends data to the Pi, where a Python program does the business of converting the spectrum to data. [Les]’s software is simple by complete, giving a graphical representation of the spectral data it sees. The video below shows the build process and what’s involved in calibrating the spectrometer, plus some of the more interesting spectra one can easily explore.

We appreciate the simplicity and the utility of this design, as well as its adaptability. Rather than using machined aluminum, the spectroscope holder and Pi cam bracket could easily be 3D-printer, and we could also see how the software could be adapted to use a PC and webcam.

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Hackaday Links: November 22, 2020

November 22, 2020 by Dan Maloney 6 Comments

Remember DSRC? If the initialism doesn’t ring a bell, don’t worry — Dedicated Short-Range Communications, a radio service intended to let cars in traffic talk to each other, never really caught on. Back in 1999, when the Federal Communications Commission set aside 75 MHz of spectrum in the 5.9-GHz band, it probably seemed like a good idea — after all, the flying cars of the future would surely need a way to communicate with each other. Only about 15,000 vehicles in the US have DSRC, and so the FCC decided to snatch back the whole 75-MHz slice and reallocate it. The lower 45 MHz will be tacked onto the existing unlicensed 5.8-GHz band where WiFi now lives, providing interesting opportunities in wireless networking. Fans of chatty cars need not fret, though — the upper 30 MHz block is being reallocated to a different Intelligent Transportation System Service called C-V2X, for Cellular Vehicle to Everything, which by its name alone is far cooler and therefore more likely to succeed.

NASA keeps dropping cool teasers of the Mars 2020 mission as the package containing the Perseverance rover hurtles across space on its way to a February rendezvous with the Red Planet. The latest: you can listen to the faint sounds the rover is making as it gets ready for its date with destiny. While we’ve heard sounds from Mars before — the InSight lander used its seismometer to record the Martian wind — Perseverance is the first Mars rover equipped with actual microphones. It’s pretty neat to hear the faint whirring of the rover’s thermal management system pump doing its thing in interplanetary space, and even cooler to think that we’ll soon hear what it sounds like to land on Mars.

Speaking of space, back at the beginning of 2020 — you know, a couple of million years ago — we kicked off the Hack Chat series by talking with Alberto Caballero about his “Habitable Exoplanets” project, a crowd-sourced search for “Earth 2.0”. We found it fascinating that amateur astronomers using off-the-shelf gear could detect the subtle signs of planets orbiting stars half a galaxy away. We’ve kept in touch with Alberto since then, and he recently tipped us off to his new SETI Project. Following the citizen-science model of the Habitable Exoplanets project, Alberto is looking to recruit amateur radio astronomers willing to turn their antennas in the direction of stars similar to the Sun, where it just might be possible for intelligent life to have formed. Check out the PDF summary of the project which includes the modest technical requirements for getting in on the SETI action.

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Oh, Holey Light

September 30, 2020 by Brian McEvoy 18 Comments

We consider ourselves well-versed when it comes to the technical literature plastered on hardware store parts. Acronyms don’t frighten us, and our Google-fu is strong enough to overcome most mysteries. One bit of dark magic we didn’t understand was the gobbledygook on LED lamps. Wattage is easy and color temperature made sense because it corresponds with warm and cool colors, but Color Rendering Index (CRI) sounds like deep magic. Of course, some folks understand these terms so thoroughly that they can teach the rest of us, like [Jon] and [Kevin], who are building a light controller that corrects inadequacies in cheap lamps by installing several lamps into one unit.

We learned a lot by reading their logs, which are like the Cliff Notes from a lighting engineer’s textbook, but we’ll leave it as an exercise for the students to read through. Their project uses precise light sensors to measure the “flavor” of light coming off cheap lamps so you can mix up a pleasing ratio. In some ways, they are copying the effects of incandescent bulbs, which emit light relatively evenly across the visible light spectrum, right into the infrared. Unfortunately, cheap LEDs have holes in their spectrum coverage, and a Warm White unit has different gaps compared with Daylight, but combining them just right gives a rich output, without breaking the bank.

DIY Radio Telescopes Hack Chat

February 10, 2020 by Dan Maloney 8 Comments

Join us on Wednesday, February 12 at noon Pacific for the DIY Radio Telescopes Hack Chat with James Aguirre!

For most of history, astronomers were privy to the goings-on in the universe only in a very narrow slice of the electromagnetic spectrum. We had no idea that a vibrant and wondrous picture was being painted up and down the wavelengths, a portrait in radio waves of everything from nearly the moment of creation to the movement of galaxies. And all it took to listen in was an antenna and a radio receiver.

Over the years, radio telescopes have gotten more and more sophisticated and sensitive, and consequently bigger and bigger. We’re even to the point where one radio telescope often won’t cut it, and astronomers build arrays of telescopes spread over miles and miles, some with antennas that move around on rails. In the search for signals, radio astronomy has become the very definition of “Big Science.”

But radio astronomy doesn’t have to be big to be useful. James Aguirre, an astronomer at the University of Pennsylvania, spends his days (and nights) studying the radio universe with those big instruments. But he’s also passionate about down-scaling things and teaching everyone that small radio telescopes can be built on the cheap. His Mini Radio Telescope project uses a cast-off satellite TV dish and a couple of hundred bucks worth of readily available gear to scan the skies for all sorts of interesting phenomena.

Dr. Aguirre will join us on the Hack Chat to discuss all things radio astronomy, and how you can get in on the radio action on the cheap. Chances are good your junk pile — or your neighbor’s roof — has everything you need, and you might be surprised how approachable and engaging DIY radio astronomy can be.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 12 at 12:00 PM Pacific time. If time zones have got you down, 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. Continue reading “DIY Radio Telescopes Hack Chat” →