persistence

2 Articles

Real Radar Scope CRT Shows Flights Using ADS-B

April 15, 2023 by 12 Comments

Real-time flight data used to be something that was only available to air traffic controllers, hunched over radar scopes in darkened rooms watching the comings and goings of flights as glowing phosphor traces on their screens. But that was then; now, flight tracking is as simple as pulling up a web page. But where’s the fun in that?

To bring some of that old-school feel to his flight tracking, [Jarrett Cigainero] has been working on this ADS-B scope that uses a real radar CRT. As you can imagine, this project is pretty complex, starting with driving the 5FP7 CRT, a 5″ round-face tube with a long-persistence P7-type phosphor. The tube needs about 7 kV for the anode, which is delivered via a homebrew power supply complete with a custom flyback transformer. There’s also a lot going on with the X-Y deflection amps and beam intensity control.

The software side has a lot going on as well. ADS-B data comes from an SDR dongle using dump1090 running on a Raspberry Pi 3B. The latitude and longitude of each plane within range — about 5 nautical miles — is translated to vector coordinates, and as the “radar” sweeps past the location, a pip lights up on the scope. And no, you’re not seeing things if you see two colors in the video below; as [TubeTime] helpfully explains, P7 is a cascade phosphor that initially emits a bright-blue light with some UV in it, which then charges up a long-persistence green phosphor.

Even though multicolored icons and satellite imagery may be more useful for flight tracking, we really like the simple retro look [Jarrett] has managed to pull off here, not to mention the hackery needed to do it.

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Phosphorescent Laser Painting

January 18, 2011 by 23 Comments

 

Here’s a simple and interesting idea that increases the visual persistence of a laser scanner image. Using glow-in-the-dark paint, [Daito Manabe] prepares a surface so that the intense light of a laser leaves a trace that fades slowly over time. He’s using the idea to print monochromatic images onto the treated surface, starting with the darkest areas and ending with the lightest. The effect is quite interesting, as the image starts out seeming quite abstract but reveals its self with more detail over time.

As evidenced in the test videos, the bursts of laser scanning are matched to the fade rate of the paint. Therefore it would seem that the time taken to “write” an image is directly proportional to the desired visual persistence of the final image. We wonder, by combining clever timing and variable laser intensity could you write images much more quickly? How hard would it be to use this for moving pictures? With the ability to create your own tiny laser projector, and even an RGB scanner, there must be a lot of potential in this idea for mind-blowing visual effects. Add portability by using a phosphor-treated projection screen!

Share your ideas and check out the test videos after the break.

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