Quantum Gypsies

• Messaging Archeology -->
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• Introduction
• What does it mean?
• Greek Fire
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Before we begin this little history of how messages were sent and received over distances, we need to consider the message itself. At its most basic level, a message has to have some meaning and people sending and receiving the message have to agree on that meaning. We find difficulty with meaning in our face to face and printed page to face messages. I was reading on the BBC news web site about a group of businessmen from a number of different countries all understanding each other well when they spoke in English, except for one guy, an Englishman. As English becomes the language of global communication, so it is morphing into a set of meanings that people brought up on the nuances of U.K. English find difficultly in understanding.

Even when two native speakers of a language communicate, there can be problems in the meaning of messages. Take the phrase "I was reading about reading." If it is spoken, the meaning is clear from the pronunciation , reading pronounced reeding is about printed matter and reading pronounced redding means a town in the south of England. If the phrase is written however, we need some extra help to make the difference in meaning clear, like the first letter of the town being capitalised giving "I was reading about Reading." When we are sending messages over a long distance therefore, the first problem is to ensure that we use an agreed way of encoding meaning, whether that be human language, Morse code, semaphore flags or the arrangement of electrical signals.

The second problem is to agree on what is called a protocol for sending and receiving messages. That simply means an agreed method of starting and stopping messages, of putting spacing between symbols in the message and of correcting errors. Again, it's a common problem in our short distance communication. How many times have you butted in when someone is talking to you, just because you think that they have finished speaking? We actually have short protocol phrases in English to try to overcome this problem. For example, ending a spoken message with a question, such as "What do you think?", which signals that I have finished speaking.

For long distance messages, where the sender and receiver do not necessarily speak each others language, or where the transmission and reception of messages may be handled by machines, it is absolutely vital that we agree in advance on a message handling protocol.

I am going to use Morse code as an example of coding meaning and protocol, but the problems are exactly the same whatever message code is used, so I could have just as easily used a telephone system to illustrate them.

The meaning and protocol of Morse code

To set the scene, you need to know that in Morse code, a short keypress or dot is conventionally represented by "DIT" and a long keypress or dash is conventionally represented by "DAH" or "DA".

The following sounds come through your headphones -- DIT DIT DIT    DAH DAH DAH   DIT DIT DIT -- does that mean SOS or get me a beer? It depends on the agreed coding of meaning. In Morse code it means SOS, but it could equally well mean anything you want it to. What does SOS mean? SOS is the accepted international distress code, but that has only been true since around 1908, before that the most common distress signal was CQD, which means "Call to Quarters - Distress!" In Morse code CQD translates to DAH DIT DAH DIT DAH DAH DIT DAH DAH DIT DIT, which is a bit more difficult to key when your boat is sinking around you.

Of course, before the twentieth century it did not matter what the distress signal was at sea, because no ship had a radio to send it, but it was used on the American overland telegraph. You must have seen it in Westerns when the plucky telegraph operator taps out his last message after being shot by the Dalton gang.

When Samuel Morse originally used the code on his telegraph system, users did not listen to tones but to the clicks created by sounders, so long key closures (DAHs) were sent as two short key closures (DITs). The characters making up SOS would therefore be sent as DIT DIT DIT DIT DIT DIT DIT DIT DIT DIT DIT DIT and it becomes easy to see that you need to know where the gaps in letters occur, which is where the protocol comes in. A series of twelve DITs could be SOS or BAD in American Morse and I55 in international Morse depending on where you put the gaps between letters.

For a short time in the early part of the twentieth century, both American Morse and international Morse were in use on the Eastern seaboard of the U.S. Which could have led to some disastrous confusion.

We now need to wrap the text of a message in some sort of container that tells us that we have a complete message and this is achieved with Morse procedural signals, or prosigns. These are two or three character codes that are sent without spaces between the letters. For instance SK means "signing off" and is sent as DIT DIT DIT DAH DIT DAH. Prosigns were also used as abbreviations for station identifiers, common words and long winded technical terms. Think of teenagers texting and you've got the idea.

We can now construct a complete message between say a railroad baron in New York (call sign NW)and his Chief accountant in Los Angeles (call sign LA). You just need to know the following prosigns:

DE means "this is"
K means "listening" or "back to you"
BT means a separator and is often written as "="
KN means will named party please reply
SK means "signing off"

So sending a message in Morse code is not just about the meaning of the code, you also have to know the message protocol that allows complete messages to be constructed.

The same everywhere

If you look around, you can see message meaning codes and protocol codes all over the place. Comic books have a protocol that speech appears as bubbles flying out of the speakers mouth. Cigarette adverts have to abide by a protocol that they cannot equate smoking and sex and they also have to carry some code meaning that smoking kills you.

Most of the time the codes and protocols are so well known that we don't think of them as such, but for long distance communication it is vital that meaning codes and protocol codes are understood by everyone involved before any attempt is made to send a message. So there has to be some means of building up knowledge from scratch and spreading that knowledge to anywhere we want to send messages.

If I want to send you a letter, I first need to teach you my language and that has to be done face to face until you can read. I then have to invent paper and pencils and start up a post office. I now have to show you how to cut a hole in your door for letters to drop through. Someone, maybe you, has to invent an address for you that the newly employed postman can understand. Then you have to tell a friend of yours that is visiting me what that address is, and that friend will have had to have visited me previously, in my company, to know where I live. I have to learn to write, and if you saw my handwriting you would understand how important this bit is. Finally, I can write you a letter, which is safely delivered by the postman, not difficult as he only has one delivery address so far. The letter drops through your hole in the door and is immediately chewed up by your dog. Somehow it seems easier just to paddle up the Orinoco and visit you in person.

The point that I am labouring here as that a whole host of things have to have happened before we can communicate with the meaning codes and protocol codes of the World Wide Web. So it is just as well that we have been at it for two and a half thousand years.

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Last updated 05 November 2010