jwm@stdc.jhuapl.edu (Jim Meritt) (10/13/89)
From: jwm@stdc.jhuapl.edu (Jim Meritt) From: dep@ius3.ius.cs.cmu.edu (David Pugh) }In article <10104@cbnews.ATT.COM> jwm@stda.jhuapl.edu (Jim Meritt) writes: }>The Navy (NATO, anyway) uses signal flags for tactical signals. ... }>It is the ONLY way at sea under radio silence - messengers don't swim }>that fast. :-) }>[mod.note: Surely we haven't forgotten how to use signal beacons ? - }>Bill ] } }Or how about a low-power laser? If the entire "footprint" of the laser falls }within the target (which should be easy enough to do: use a laser with a }small divergence and adjust the aim whenever it drifts too near the edge }of the target), the signal should be undetectable. What's wrong with signal lights? Every ship has them, every ship uses them. They are easy to detect for the receiver (like, you SEE them). They are directional, they are relatively fool proof (lightbulbs are easy to replace). They are good to the horizon. -- "People think it must be fun to be a super genius, but they don't realize how hard it is to put up with all the idiots in the world." - Calvin ............................................................................. jwm@aplvax.jhuapl.edu,jwm@aplvax.uucp,meritt%aplvm.BITNET,jwm@aplcen.apl.jhu.edu
budden@manta.nosc.mil (Rex A. Buddenberg) (10/14/89)
From: budden@manta.nosc.mil (Rex A. Buddenberg) The main reason signal lights (flag hoist and semaphore too) are poor choices is the extremely limited bandwidth. Typical FL data rates are in the 5 W/M neighborhood. (The only times we'd man the signal team on CG cutters was when we worked with the Navy. Since Coast Guard has no signalmen, the team was taken from the Quartermaster locker -- and usually salted with a Radioman or two who was good to a couple dozen W/M CW.) The bit error rate is usually pretty high too. And the labor cost is excessive (include critical skill level training in that equation). The other reason is that that is not the way we operate any more. Battle groups are spread out well beyond the horizon and the premium is currently on extended line of sight comms, not line of sight. Rex Buddenberg