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Spectrum analysis is a technique that allows someone to observe the amplitude of various frequency ranges within a signal. The most common use case is in the world of audio engineering, as it is useful for tuning audio output. It can, for example, show you that a particular audio signal has little amplitude in the low bands and that tells you that you should turn up the bass. If you want to try this for yourself, Sam Dartel designed a DIY spectrum analyzer that is easy for beginners to build.

For a spectrum analyzer to work, it needs to be able to break an electrical signal down into a series of frequency ranges. In an audio signal, frequency is pitch. That means that higher frequency ranges correspond to higher notes in the audio. This spectrum analyzer utilizes an MSGEQ7 IC hip, which is an equalizer filter, to pull seven frequency ranges from an audio signal. It outputs the peak of each band, giving a real-time reading of each band’s amplitude.

There are two versions of this spectrum analyzer: one powered by a battery and one powered via USB. Both are shields for An Arduino Nano board, which takes the output from the MSGEQ7 and uses the FastLED library to set the number of LEDs lit on seven WS2812B individually addressable RGB LED strips. Each strip is a 2D display and that is enough for the amplitude of each band, but the color and brightness of the LEDs introduce two other possible dimensions. This spectrum analyzer uses those for different effects patterns.

To build this spectrum analyzer, you’ll need to have one of the two shield PCB designs fabricated. All of the components are through-hole to make assembly easy.

The post DIY spectrum analyzer is an easy project for beginners appeared first on Arduino Blog.

Spectrum analyzers are a great way to visualize music, and “TUENHIDIY” came up with an interesting take on this device using not one, but four Arduino Uno boards.

Each Uno receives the same sound input via a 3.5mm audio jack, and separately processes it to break out the left and right channels, as well as upper and lower frequency ranges using fast Fourier transforms, or FFTs.

36 different bands are shown on four LoL Shields, with each 9×14 Charliexplexed LED matrix attached to an Uno, for a total of up to 504 individual points of light. Everything is put together on an acrylic plate, and powered by a portable USB battery.

TUENHIDIY is quick to note that it’s a “crazy project,” but as seen in the video below, it looks like a lot of fun!

Remember the Girl Tech IM-me? It was a hot-pink clearance rack toy that suddenly became one of the hottest commodities in the hacking world when it was discovered they could be used for all sorts of radio frequency shenanigans. Now they go for triple digits on eBay, if you can even find one. Well, we’re probably about to see the same thing happen to the Smart Response XE.

Thanks to the work of a hacker named [ea], this cheap educational gadget is finally starting to live up to the potential we saw in it back when a teardown revealed it was powered by an Arduino-compatible ATmega128RF chip. With a big screen, a decent QWERTY keyboard, and integrated wireless hardware, it seemed obvious that the Smart Response XE was poised to be the next must-have repurposed piece of kit.

Though as it turns out, [ea] isn’t using the device’s built-in wireless hardware. Step one in this exceptionally well documented and photographed project is to tack a CC1101 transceiver module to the SPI pins on the ATmega128RF. Then with the appropriate firmware loaded up, that nice big screen will show you what’s happening on the 300 MHz, 400 Mhz and 900 MHz bands.

But the fun doesn’t stop there. With the CC1101-modified Smart Response XE, there’s a whole new world of radio hacks you can pull off. As a proof of concept, [ea] has also included a POCSAG pager decoder. Granted the RTL-SDR has already made pulling pager messages out of the air pretty easy, but there’s something to be said for being able to do it on something so small and unassuming.

If you can’t tell, we’re exceptionally interested in seeing what the community can do with the Smart Response XE. At the time of this writing, the going rate on eBay for a good condition unit looks to be about $10 USD, plus the $3 or so for the CC1101 module. But the prices went through the roof when we first posted about it, so get them cheap while you still can.

[Thanks to bburky for the tip.]

Getting an old traffic light and wiring it up to do its thing inside your house isn’t exactly a new trick; it’s so common that it wouldn’t normally pass muster for these hallowed pages. Even using one up to show the real-time status of your build or system resource utilization would be pushing it at this point. To get our attention, your traffic light is going to need to have a unique hook.

So how did [Ronald Diaz] manage to get his project to stand out from the rest? Interestingly enough, it’s nothing you can see. His traffic light doesn’t just look the part, it also sounds like the real thing. With far more effort and attention to detail than you’d probably expect, he’s made it so his Australian pedestrian traffic light correctly mimics the complex chirping of the original.

Working from a video of the traffic light on YouTube, [Ronald] was able to extract and isolate the tones he was after. Performing spectral analysis on the audio sample, he was able to figure out the frequency and durations of the eleven individual tones which make up the complete pattern. From the 973 Hz tone that only lasts 25 ms to the continuous 500 Hz “woodpecker”, every element of the sound was meticulously recreated in his Arduino code.

The Arduino Pro Mini used to control the traffic light is not only responsible for playing the tones through a piezo speaker, but as you might expect, for firing off the relays which ultimately control the red and green lamps. With everything carefully orchestrated, [Ronald] can now get that authentic Australian side-of-the-road experience without having to leave the comfort of his own home.

If you’d rather your in-home traffic light be more useful than realistic, we’ve got plenty of prior art for you to check out. This traffic light that tells you how the value of Bitcoin is trending is a great example. Or maybe this one that can tell you if the Internet is down.



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