The simple idea that sound can be transformed into shapes fascinates me.
How Does It Work?
An oscilloscope provides a visual representation of sound or electronic waves. Typically, you see a wave pattern running from left to right.
However, when you put the oscilloscope into x-y mode, one channel of sound produces a line on the x-axis, and the other channel of sound makes a line on the y-axis. By creating a stereo signal, one can represent the sound in two visual dimensions.
Oscilloscopes Through Time
This visual representation is the basis of vector graphic monitors that were used on the first computer displays in the late 1950s. In fact, these displays were oscilloscopes. Before the pixel was invented, it was easier for a computer to draw with vectors since they take up even less memory than bitmap images.
Computers were invented to defend against attacks during the Cold War. The first one, called Whirlwind, was built by MIT for the Navy in 1951. Later, the Air Force assumed ownership to intercept incoming bombers.
Some of Whirlwind’s output interfaces included oscilloscopes, typewriters, speakers, and lights. The Whirlwind was featured on See It Now with Edward R. Murrow with oscilloscope output.
Following Whirlwind, another oscilloscope called SAGE (Semi-Automatic Ground Environment) was built with IBM AN/FSQ-7 computers. It was used to display maps and incoming aircraft so that they could be targeted by use of a light gun. Wikipedia says, “The AN/FSQ-7 had 100 system consoles, including the OA-1008 Situation Display (SD) with a light gun, cigarette lighter, and ash tray.“ This is one of the earliest computers I have seen with a map drawn on the screen.
The following 1956 clip shows the Display Scope in action is from _On Guard! _which tells the story of SAGE:
This technique of making images with circuits and an oscilloscope was also used in the title sequence of Alfred Hitchcock’s Vertigo.
My Oscilloscope Adventure
When I first found a program called Rabiscoscopio, I immediately began shopping for an oscilloscope on eBay.
My first purchase of a Hitachi oscilloscope for $17 was a bust, since it arrived with only one channel working. The key is to get an oscilloscope that has at least two channels and supports x-y mode display. The Hitachi 20 MHz would have worked great if only it had two working channels.
My next purchase of a Leader 20 MHz dual-channel oscilloscope for $39.99 was more successful. I tried out the image of the umbrella provided by Alex, and it worked!
Since my goal was to use the oscilloscope to generate the Volume Integration logo, I proceeded to the next step of attempting to draw my own pictures with Rabiscoscopio. I found that some BNC Male Plug to RCA Female Jack Adapters were the best way to connect my computer to the oscilloscope by plugging the headphone jack into an RCA cable.
At first, I tried to take a standard Scalable Vector Graphics (SVG) file and convert it to sound with Rabiscoscopio. This caused it to throw an error. Apparently, I did not read the instructions where it says to only use straight lines and only use one continuous line.
I found Inkscape to be the easiest free tool for creating graphics. My experiments also led me to discover that drawing lines that cross each other also causes problems. Here is a gallery of my early experiments:
This is my refined process:
- Find image to trace.
- Open Inkscape.
- Import original image to trace over it.
- Use the pencil tool to trace a single line around the image in straight segments without crossing. Finish without joining the beginning and end of the line.
- Delete the original traced image.
- Save as SVG file.
- Open Rabiscoscopio and SVG file.
- Rabiscoscopio will generate the WAV sound file automatically.
- Plug in sound output from headphone jack to oscilloscope.
- Turn on oscilloscope and play sound file.
- Watch and enjoy, or go back and refine drawing.
Drawing the Volume Logo
My next feat was to draw the Volume Integration logo. It turned out to be more difficult than I expected because of all the intersecting lines and 3D-like shapes. The SVG file ends up looking like this:
The most difficult part was drawing a continuous line without crossing previous lines. After multiple attempts, a picture of the final product emerged.
I have also included the wav file for your listening enjoyment. If you have an oscilloscope, you can watch it appear! You can use a software based oscilloscope by loading this software called Oscilloscope! on your computer.