"It came to me in a dream and I forgot how it worked in another..."
How hard can it be to visualize sound. Really? No? No one on the internet builds this? That's stupid! Screw it, I'll build one. How hard can it be?
And so it begins. I'm not starting this project with nothing to show already I think that's foolish. But I do know that I know almost nothing about audio engineering or electronic design and this is going to be a learning experience for me and my wallet... probably.
I started off by building a vb.net waterfall type project that simply colours squares (pixels) for each sample that it receives via comm port from the Arduino Uno and it's hilariously badly wired sr-04 sensor I pulled off my quadcopter. (Vibrations and ultrasonics apparently don't play nice together)
Some tweaking later on colours and double translation math has a working visualizer for the data streaming from the Arduino. Proof of concept complete. Lets build a small scale prototype to better fleshout the concept and get some better/more usable imagery on the waterfall. 10 sr-04's ordered from Ebay. (Edit: Damn 4 weeks... ordered 3 more from Amazon with prime, they get here Monday)
Now how do we narrow the sample beams down to get better resolution? I mean, I can see when I sweep it past my monitor that the monitor surface is above the wall surface. But I know what I'm looking for. It doesn't do much good if you didn't know what to look for. Wikipedia says that the US Navy's top of the line (in 1960s) swath sonar used 61 beams at 1 degree precision. How did they get 1 degree precision on sonar? Which led me to the joys of phased sound arrays and directional sound with some crossover on rf theory. Great more stuff that is black magic to me... Also for note, a 6 degree beam ultrasonic sensor is nearly $130.00 USD.
Now I'm left wondering until next week how I'm going to trigger ultrasonic pulses close enough together to form the precise wave front that I need to get anywhere near the precision of 1 degree. Modern arrays have a beam resolution of 0.016 degrees!.
I assume building something in hardware is the best way to tackle this. Expensive systems seem to use a flat plate that resembles a solar panel. I assume it's an array of pizeo drivers in a low/non resonating substrate. I don't hope to achive their results, I'll settle for far less. I figure an array of 60 scanning transducers, with an extra one for wave forming/limiting on each end. A linear line of 61 transducers on both sides. (total count is 184 individual transducers fired in sets of 5) Probably means I'll be ordering transducers to buildup a large grid and figuring out some way of either using a few transducers to fire a ping and the bulk of them to listen or figuring out how to multiplex all of them. Probably some fancy function generators that I don't know how to build yet. Amplifiers and Gain control. (My giant book from element 14 has those covered though)
I'll test out multiple pings with a JSON style return on serial and see if the images I get from the waterfall are more recognizable. I know in air they aren't going to be great but after I test that, I'll waterproof the boards and test in a liquid medium to see what I end up with. Post more next week. Thanks for reading!