Re: [math-fun] Miss those IBM/DEC blinking lights?
I'm surprised that auto LED headlights don't already broadcast their vehicle VIN# (maybe they do?). Apparently, one of the countries in the Middle East is now requiring some sort of RFID IFF for automobiles. Sure makes the CIA drone program a lot more accurate... I've heard that Disney is starting to replace some of its nighttime *fireworks* displays with *LED drone fleets* displays. I would imagine that some of these temporal streaks could be useful for these drone displays. At the last several CES's (Consumer Electronics Shows), I talked with vendors making bicycle LED displays, and none of them were very imaginative. I did see a T-shirt with a bit-mapped display, but it *wasn't programmable* !! What weren't they thinking? How come I still can't buy a T-shirt with a bitmapped display on it? -- it might be great for political protests, etc. It might be fun to hack the news cameras by synchronizing the T-shirt display with a GPS-derived 60Hz signal; with proper synchronization, it might be possible to have the TV news cameras pick up completely different content from that perceived by human observers! I seem to recall that someone at MIT had developed an LED display for bicycle spokes that was time-multiplexed in such a way as to provide a full circular bit-mapped display -- kinda like those WWII radar displays. At 01:28 AM 4/10/2018, Bill Gosper wrote:
It should also be possible to Morse-code messages by rapidly blinking LED auto taillights to leave dotted and dashed afterstreaks, if you know how to look.
On 2018-04-11 07:30, Henry Baker wrote:
I seem to recall that someone at MIT had developed an LED display for bicycle spokes that was time-multiplexed in such a way as to provide a full circular bit-mapped display -- kinda like those WWII radar displays.
These last have been around for at least 10-15 years. I may be picking at nits, and I haven't looked at one closely, but I'd guess that it was positionally multiplexed (if you know what I mean), not time-multiplexed. Assuming my guess is correct, the area covered by an LED closer to the rim would be larger (blurrier?) than the LEDs closer to the hub. The value of an LED would be dependent on the position of the wheel, and independent of rotational speed, and robust against variations in speed. Of course, the image wouldn't be very persistent or clear until you got above 2 or 3 frames per second, so you'd need to be going fast enough for the wheels to be rotating at 3*60/<# of spokes with LEDs> RPM. If you can fit 256 LEDs on a spoke you'd have a 512x512 display, but probably much smaller is more realistic -- but even 32x32 is sufficient for scrolling text.
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https://giphy.com/explore/monkey-light On Wed, Apr 11, 2018 at 11:32 AM, Michael Greenwald <mbgreen@seas.upenn.edu> wrote:
On 2018-04-11 07:30, Henry Baker wrote:
I seem to recall that someone at MIT had developed an LED display for bicycle spokes that was time-multiplexed in such a way as to provide a full circular bit-mapped display -- kinda like those WWII radar displays.
These last have been around for at least 10-15 years. I may be picking at nits, and I haven't looked at one closely, but I'd guess that it was positionally multiplexed (if you know what I mean), not time-multiplexed. Assuming my guess is correct, the area covered by an LED closer to the rim would be larger (blurrier?) than the LEDs closer to the hub. The value of an LED would be dependent on the position of the wheel, and independent of rotational speed, and robust against variations in speed. Of course, the image wouldn't be very persistent or clear until you got above 2 or 3 frames per second, so you'd need to be going fast enough for the wheels to be rotating at 3*60/<# of spokes with LEDs> RPM. If you can fit 256 LEDs on a spoke you'd have a 512x512 display, but probably much smaller is more realistic -- but even 32x32 is sufficient for scrolling text.
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-- Forewarned is worth an octopus in the bush.
On Wed, Apr 11, 2018 at 8:30 AM, Henry Baker <hbaker1@pipeline.com> wrote:
How come I still can't buy a T-shirt with a bitmapped display on it? -- it might be great for political protests, etc.
https://glowproducts.com/us/programmable-message-led-shirt http://www.getsygnal.com/products/Message-LED-T-Shirt-Men https://www.alibaba.com/product-detail/led-T-shirt-display-for-live_17598481... Looks like e-ink is coming on cloth soon. Apparently the tech is all done; they're just looking for investors. https://www.youtube.com/watch?v=J17KgbjYMro https://www.youtube.com/watch?v=_tF2GddZqkg -- Mike Stay - metaweta@gmail.com http://www.math.ucr.edu/~mike http://reperiendi.wordpress.com
participants (4)
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Henry Baker -
Michael Greenwald -
Michael Kleber -
Mike Stay