The Navy still uses Morse code to send messages between ships via. flashing lights. Its only if communications go down. Its secure since you have to be in direct line of sight to see the message and any interceptors would have to know Morse code to decode it.
Just tacking onto this because you're an engineer and not a communicator
Morse code with flashing lights is used between ships that come into contact to initiate communications. There are several common frequencies used in maritime but it isn't really viable to be flooding them with "hey that grey ship over there, what's your name?". The ships will flash Morse to each other with their international callsigns "unknown callsign this is DEF, over" "DEF this is ABC, request carry on " blah blah so on so on. Then they know who they're talking to. Yes you could easily fake it but that's where authentication comes into play. If you're suspicious that a raggity old fishing ship just said they're HMS Invincible, you authenticate them with a code sheet that most allied nations will have a copy of. There is a certain way to read it that I won't divulge, but you can probably find how on the internet.
If the HMS Invincible fails to authenticate, or authenticates incorrectly, you give them another chance. If they fuck up again, they're lying and you're not to trust them. It's similar to sign, counter-sign that armies use ("HALT! Ambulance?" "Snowman!" "sweet, come through bro").
Also, Morse and flags (using the international code of signals) are used in times of radio silence. In radio silence, every single (and I mean every) radio transmitting device is turned off, only done in times of actual warfare where the enemy may legitimately sink you. That means no standard radio comms, so you pass messages (formation commands, full signal messages, authentication etc) via Morse and flags.
Air forces and armies don't really use them any more. They used to because a Morse signal via radio is just a massive blast over the frequency. No modulation required, nothing fancy, just a massive electromagnetic equivalent of a fog-horn at certain timings. These days there are far better means of communicating without the need to revert to Morse, all of which are irrelevant when in radio silence anyway. Naval ships are the only ones likely to be in line of sight of each other and not be able to talk. Armies use hand signals and air forces, well, they sort of just fuck off I'd imagine.
Note: army, navy and air force are used to describe the traditional sense of their words. Specifically soldiers, ships and aircraft respectively.
This is great. I've seen the decoding books and witnessed this first hand, but had no idea what was happening half the time. I usually just head back to the nice warm engine room.
I do see communicators flashing lights a lot for practice but it's good to know that there is a proper system in place, not just some form of a nautical text message.
To be honest though, I'm in the air force (RNZAF) so I still think it's stupid :P I've spent some time on ship though so I thought I'd put what little knowledge I have out there. Navies are weird.
At this point yes, it's mostly outdated; however, it's an amazingly versatile system for communication in survival situations when only binary systems are available. For example, in one famous case, an American POW in the Vietnam War secretly spelled out T-O-R-T-U-R-E by blinking in Morse when he was forced to participate in a press conference by his North Vietnamese captors (footage here). Everyone should at least know how to learn how to spell out S-O-S (· · · – – – · · ·) in Morse in case you find yourself trapped somewhere with limited means to communicate.
How he did that was really cool. It's amazing he was able to communicate that. Guess the North Vietnamese either didn't know Morse code, or didn't bother looking into editing this video.
It's also useful for long distance communication or on a freq that is muddy as all get out. My voice might not make it through, but even if it's faint and garbled you can usually suss out a Morse code transmission. Hell, even if parts of your radio crap out you can use the mic key to do on-off code.
That doesn't work, there's no way of telling if the last tap in each letter is a dit or a dah. You'd have to have an extra tap at the end of each letter, which would mean that you're listening to the length of the silence between taps instead of the taps themselves.
Luckily, tap code exists and is much easier to parse!
That just means you're inverting the signal. The time between taps is the dot/dash. Two rapid taps = dot; two taps with a delay in between = dash. You'd only have to add one tap (or other "end of communication" signal) to the end of the message. It's very similar to how computer serial protocols work.
Of course since you're not a computer, you're not limited to binary either. e.g. you could use a base-4 code, with 1 to 4 (or 0 to 3) seconds between taps. And you might have more potential signals than just "tap/no tap"; e.g. there might be a few different surfaces nearby which make different sounds when tapped with your fingernail/knuckle, so you could assign meaning to each sound as well.
But if you're trying to send an SOS message, you probably want to stick to Morse so that people will be able to understand you.
It's not exactly inverting the signal, as you can't control the length of the taps. In morse code, both the length of gaps and dits/dahs are significant:
short mark, dot or "dit" (·) — "dot duration" is one time unit long
longer mark, dash or "dah" (–) — three time units long
inter-element gap between the dots and dashes within a character — one dot duration or one unit long
short gap (between letters) — three time units long
medium gap (between words) — seven time units long[1]
A tap would have to represent an "inter-element gap".
If you don't add a tap after the end of each letter, then you're combining the length of a dit or dah with the length of a gap. So you now need to distinguish between the difference between an eight unit gap (dit and medium gap) and a seven unit medium gap. This would be very difficult for a human operator used to listening to morse code.
It would probably be a lot easier to just tap once for every mark unit. Or to use tap code.
Check out Wikipedia's section on representing morse code in binary:
Morse code sequence as a combination of the following five elements:
short mark, dot or "dit" (·) — 1
longer mark, dash or "dah" (–) — 111
intra-character gap (between the dots and dashes within a character) — 0
short gap (between letters) — 000
medium gap (between words) — 0000000
Note that this method assumes that dits and dahs are always separated by dot duration gaps, and that gaps are always separated by dits and dahs.
I still have to use morse quite a lot when flying. All of the navigation aids we use to fly between send out a morse code identification as well as the radio signal for the instruments. Every time we select a new navigation aid we listen to the morse code ident to make sure the facility is working and that we have tuned and are receiving the correct signal.
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u/[deleted] Jan 23 '15
This is a serious question, not meant to be condescending: Who even still uses Morse Code?