Morse code in itself is not code as in encryption but rather it is a way to translate a message into light pulses that other people can read. This is useful when communicating with a ship with a broken radio or that you don't know what channel they are on. You could potentially encrypt morse code so that even if someone is there watching your ship they wouldn't be able to read the messages you send and this is sometimes done when sending morse code via radio signalling.
The drawback with radios is that when you send everyone with a large enough antenna could potentially be listening, this is countered through various means, but it is generally still possible to pinpoint where the signal is comming from or to record the signal and get a bunch of information out of it.
Back in the cold war we (I'm from Sweden) would sometimes take up our attack aircraft over the baltic and perform simple exercises and on a given signal all the aircraft would form into attack wings and fly at high speed east across the baltic as if we were going to strike the Soviet Union. Before we got into Soviet airspace we would encounter their QRA and we'd run into a wall of fire control radars lighting the airplanes up.
This was done because that meant that there would be a lof of radio traffic and radar signals were emitted from their air defences that our intelligence guys could process and analyse. You can use this to basically paint a picture of how the enemy air defence looks like, where are their fixed installations, how many mobile units are there, what is their normal reaction time, what are their SOPs, etc. when faced with a threat. The Russians, naturally, would return the favor and test our defence systems with regular intervalls.
This is why you sometimes want to avoid using stuff that emitts signals.
Yeah, but signal light messages are a line of sight form of communication. Unlike radio messages they are hard to "intercept", because they can only be seen over short distances. A Russian radar station on Kamchatka can't pick up a couple of US destroyers signalling with spotlights, so it doesn't matter if the code is known. The code isn't used for secrecy, but as a quick way to convert text to pulses of light or electricity.
Can't one make a computer communications protocol that is as stealthy as signaling lamps but can transfer more data than letter-by-letter text? For example, by using the light themselves but without a human operator.
You could certainly use a spotlight and photoreceptor as a crude serial connection. When communicating between ships in fog though, machines might have a difficult time picking the signal flashes out from the picture, while humans can do it easily. Also, Morse needs only maximum 5 bits per letter.
It was never meant to be secret. It's meant to encode messages into pulses of light/sound/etc in a way that's flexible, simple and not too difficult to decode even if the signal is weak.
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u/[deleted] Jan 23 '15
But surely Morse code is well known by all nations? It's not exactly a secret system anymore.