As I've previously noted, I had a jolly happy time at the EE Live! 2014 conference and exhibition last week. One thing I noticed as I meandered my way around the exhibition floor was the fact that there were flashing LED displays all over the place. In particular, EETimes Community Editor Caleb Craft had created a very tasty "Applause-O-Meter" display for us to judge the winner in our Gadget Smackdown sessions.
Also, speaking of the Gadget Smackdown, one of the presenters was Jason Kridner from Texas Instruments, who dazzled the audience with his "mine is bigger than yours" audio analyzer with associated LED display.
And then, as I mentioned in my previous blog on this topic, on my way back from the conference, I ran across a mega-cool audio spectrum analyzer and display at San Jose airport. My defenses had already been weakened by the show (although not weakened enough to cause me to pay the $199.95 asking price). "Am I to be the only
man (see Creating Gender-Neutral Engineering Prose) outrageously handsome good-looking engineer on the planet without a flashy audio spectrum analyzer LED display?" I asked myself (with only a little quaver in my mental voice).
Thus it was that I decided to create my Bodacious Acoustic Diagnostic Astoundingly Superior Spectromatic (BADASS) display. The more I look around, the more I realize that there is an amazing variety of ways in which one can display the results from a spectrum analysis. Consider the following video, for example:
Here we see yet another technique for presenting the output data. In my previous blog, I showed one display that had the lower frequencies on the left and the higher frequencies on the right, and that spilt the amplitude (volume) in the vertical direction into series of colored bands (rows) -- blue at the bottom, green in the middle, and red at the top.
Also in my previous blog, we saw another display in which the different frequencies were associated with different colors in the horizontal direction. By comparison, in the case of the video shown above, the creator of this display causes all the pixels each column to change color depending on the amplitude of that particular frequency. I'm not explaining this very well -- look at the videos in my previous blog and then look at the above video and you'll see what I mean.
Now, there are several different aspects to consider when it comes to a project like this. Off the top of my head, in no particular order, we have the following questions to ponder:
- What will be the "look and feel" of the whole thing?
- What display technology are we going to use?
- Will the display handle mono and/or stereo audio streams?
- What do we need to do to pre-process the audio signal before feeding it to the control system
- Will the audio processing (extracting the audio spectrum information) be performed using analog or digital techniques?
- If we decide to use digital techniques, which algorithms will we use and how will they be implemented (microcontroller or FPGA)?
- How do we take the processed data and present the results on the display?
Since I've been spending so much time playing with Arduino Microcontrollers and Adafruit's NeoPixels recently (see my recent Building a Mind-Boggling Infinity Mirror blog), I've already made the decision that my first pass at this BADASS Display will involve a 16 x 16 array of NeoPixels. I've also decided to use the strips with 30 pixels per meter. Based on the fact that 16 x 16 = 256 pixels, and 256 / 30 = 8.53 meters, I just placed an order with Adafruit for a 9-meter length of these little scamps.
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