Friday, April 23, 2021

[gkhmwjsq] dial code

2 distinguished hands on a dial, 6 positions, avoid hands overlapping: 6*5 = 30 possiblities, enough to encode 26 letters plus a few more characters.

easily doable with a clock if hour hand does not move continuously.  more complicated if it does: clock hands coincide 11 times every 12 hours, once every 12/11 hours.

inspired by tritium vials, available in green and blue phosphors.  (but beware that their phosphors might not last as long as several half-lives of tritium.)

because the hands meet at an angle, it is unambiguous where the origin is.  but there can be ambiguity regarding which way is up.

similar to flag semaphore.

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