Re:FTP is 50 years old
by alexhutcheson on Friday April 16, 2021 @11:52AM
(#26835442)
https://en.wikipedia.org/wiki/Flag_semaphore would have been good if you needed to send arbitrary text.
Naval flags would be higher bandwidth if you could pre-arrange a modest-sized dictionary of the words and phrases you’d need.
https://www.navalgazing.net/Signalling-Part-1 is a good read.
It’s been over two decades but I think the requirement may have been an arbitrary bitstream but if not that, it was likely any of the visible ASCII characters.
Each team of four came up with their own signaling method, trying to balance how many bits were transmitted with each symbol with how quickly we could encode/decode the message.
Binoculars were not allowed. We were outside, so we didn't know how windy it would be.
I seem to recall on my team, we were sending two bits per symbol. I think it was just a large cardboard box, we colored each of the four flaps visually distinct, then unfolded one of the flaps for each symbol.
I don't recall a single team thinking to re-purpose naval flags.
Duh.