- What is information theory?
- Origins of written language
- History of the alphabet
- The Rosetta Stone
- Source encoding
- Visual telegraphs (case study)
- Decision tree exploration
- Electrostatic telegraphs (case study)
- The battery and electromagnetism
- Morse code and the information age
- Morse code Exploration
Morse code and the information age
Electric Telegraphs and developments leading to Morse Code. Created by Brit Cruise.
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- 2:31"It was formed in 1846, after its owners purchased the key needle telegraph what of the time?"
Can anyone with better listening comprehension skills help me out?(11 votes)
- I think the word is "patents".(45 votes)
- Do people still use Telegraph and/or Morse Code today?(17 votes)
Although most use of Morse Code has been supplanted by digital communications, there are still many who use it daily. These people are Amateur Radio Operators (hams), who utilize Morse code for several reasons: They enjoy mastering it as another way to communicate; they are able to speak to other hams over great distances with much less power than if they used voice; the equipment is very simple, thereby making it more compact and needing less energy to operate; for several technical reasons, Morse code can get a message through when other means of communicating can't. I believe our Special Forces military still learn Morse code to use when they have no other way to communicate. And some folks like the fact they have a "secret language".
Among hams, Morse code is referred to as CW, which stands for continuous wave. The code characters are formed by interrupting the continuous wave transmission with the "key" to form the characters.(26 votes)
- Does a computer use morse code when the keys are pressed so it can be understood? If not how does the computer understand the keys.(5 votes)
- Here's a loose description of how it works (some keyboards and computers work differently but the main ideas are the same).
In your keyboard the keys are connected to electrical switches.
A small processor called the keyboard controller that constantly scans all these switches will see when you press or release a key. It then sends a number in binary to your computer to indicate which key has been pressed or released. (Binary is the system of numbers in base 2, as opposed to the system we are used to, the decimal system, which is base 10. Binary only uses 1s and 0s as digits. )
The operating system on your computer then stores that number in a buffer ( a list containing what keys you have pressed).
Programs running on your computer can then ask the operating system what the next key pressed in the buffer was.
So from the keys on the keyboard, to the electrical switch, to the keyboard controller, to the operating system, to a computer program, is how the information flows. The information in the keyboard controller, the operating system, and the computer program are in binary.
Hope this makes sense(22 votes)
- 3:03"at a charge of 2s. 6d." s. stands for shillings, I suppose, but what about d.?(9 votes)
- "d" was used to represent pennies, which were 1/12 of a shilling. It comes from the Latin word denarius.
- Why do the letters have arrows on them?(6 votes)
- If you mean at around6:56, I think they show you the direction and strokes of writing a letter. For example, an "o" is written counterclockwise.
Now, why it was necessary to put arrows in this specific instance (explaining the Morse Code to the public) is unclear to me.(4 votes)
- 9:05(Right above the copyright line) So shillings were also used in the USA at the time? Weren't dollars in use?(6 votes)
- I'm guessing E.A. Adams & Co. wanted to sell their code book in both the US and the UK and so printed both the British and the American prices rather than having to print two versions.(5 votes)
- Did they use any punctuation?(5 votes)
- A question mark in Morse code is ..--.. or di di dah dah di dit. It might also look like IMI as this is what the individual letter are. .. = I -- = M.
- i love to communicate with morse but i dont know how!! can anyone help me(4 votes)
- can someone tell me what did all the formation of the letters in the end of the video mean?(3 votes)
- Throughout this series I have been gradually hinting that we need to think about communication as a series of selections. I use this image to get that idea across.(4 votes)
- How do we measure information nowadays instead of numbers like in the video about telegraphing companies getting ripped off by words representing phrases?(1 vote)
- Today, we measure information in bits. Those codes that you see aren't ripoffs. They are just a more efficient way of transmitting information. You know why MP3's can be a lot cheaper than CD's? It's because Apple cheats, just like the people in the video who were smart and had more efficient ways to transfer information. What those telegraph people did make uncommon words stand for phrases so the whole message was abbreviated in a few letters. Apple and other MP3 companies can sell you their music cheaper than CD because an MP3 converter deletes all frequencies that the human ear cannot hear but were recorded and take repeating parts (like the chorus) and delete all the repeats but one, which can then be played over and over in the song. The MP3 is saving information and is saving you money, just in a different way than the people in the telegraph booths. Would you call that cheating?(8 votes)
- [Narrator] In 1832, mathematician Carl Gauss and physics professor Wilhelm Weber designed a system which allowed them to communicate at a distance while they worked on their experiments, connecting the observatory with the physical laboratory. They solved a really important problem which was more of a puzzle, how to send all letters of the alphabet using one circuit or a line. And their system used a galvanometer since it was known that electric current passing through a coil creates a magnetic field pointing through the center of the loop, which could deflect a needle. But instead of merely moving a needle at a distance, their system used a switch which could reverse the direction of current instantly. This would cause the magnetic field around the coil to reverse and the needle would deflect either to the right or left depending on the direction of current, thus giving them two different signaling events or symbols, right, or left deflection. Most importantly, he assigned shorter symbols for the most common letters, such as A was a single right deflection. And E was a single left deflection. And he used the longer codes for less common letters, such as K, which was three right deflections. And at the time the speed of transmission was around nine letters per minute. All the needle telegraphs which followed suffered from a similar limitation. And it was an engineering problem. The signaling rate was slow. Now the signaling rate was the number of deflections per minute, which could be accurately transmitted and received. And if you squish signaling events together, the receiver would get confused due to jitter, resulting in errors, similar to how sustain notes on a piano will bleed together and become less recognizable if you play rapidly. And over time, the signaling rate was incrementally improved. One improvement was to add a small permanent magnet to the outside of the coil. This helped pull the needle back to neutral position after each deflection. And these designs led to a wide range of needle telegraphs which were deployed across Europe. The Electric Telegraph Company was the first public telegraph company. It was formed in 1846 after its owners purchased the key needle telegraph patents at the time. But the speed of these various needle telegraphs never surpassed around 60 letters per minute. As each needle couldn't signal much faster than one deflection per second. And initially the company build customers based on single messages, which could hold up to 20 words, which is about the length of a tweet. And by 1848, the cost of sending a single message from London to Edinburgh was 16 shillings. And this was around one week salary for say a shop owner at the time. So this technology was initially out of the hands of common people. In the United States, the commercialization of the telegraph was led by a portrait painter named Samuel Morse, who had followed development of the needle telegraphs in Europe. Morse's important because he focused on speeding up the rate at which letters could travel. He did away with needles. And in 1938, he initially submitted a patent based on the idea that electric current could either flow or be interrupted, and interruptions could be organized to create meaning. Though his designs on how to produce these interruptions were complicated involving a convoluted system of gears, levers, and electromagnets. However, his system was greatly simplified after his collaborations with Albert Vail. This led to an iconic piece of user interface, the simple spring loaded lever, or key, which can be controlled with the tap of a finger. And on the receiving end was a spring loaded lever that could be pulled and released by a strong electromagnet. To create a difference akin to the left, right deflection, he varied the length of a key press, or the pulse width, the closure of a switch for a very short time was called a dot. And the dot can be thought of as the basic unit of time in Morse code, and the closure of the switch for three units of time represented a dash. (beeping) - Spacing, exactly right. Very small tight spaces between the dits and das in a character. Di-da-dit. Di-da-di-dit. - [Narrator] And this was the source of difference in their coding strategy. Starting with an initial dot or dash left or right branch, which then leads to another dot or dash and so on. And this scheme assigned shorter symbol sequences to more probable letters based on the letter frequencies, which could be tabulated from books. So nodes high up in the tree, such as a single dot, represented E, a single dash represented T. And as we move down the tree, we place less common letters. And after a letter, this system inserts a three unit pause. - [Instructor] Spacing between the characters in a word or group is uniform too, but longer. (beeping) - [Narrator] It's important to realize that the meaning of these messages was intertwined with the timing of them. - Are you wondering if proper spacing is really so important, or is it no more than an extra refinement? A nice thing to do like neat handwriting. If you think so you're wrong and I'll show you why. (beeping) Dit for dit, and da for da, they match. Only the spacing makes the difference between one word and the other. - [Narrator] So to send the word Paris, we would first need to think of it as P space, A space, R space, I space, S. The signaling rate of the system was directly related to the tempo of the signal and music analogies were used inside training videos. - What he was sending what is the standard test word, Paris. And there you are. Each peak is a dit or a da, each valley, a space. This is excellent sending. Uniform and rhythmic. This is an example of poor hand sending, same word, Paris, but look at the difference. Irregular dits and das, half hazard spacing, no uniformity, no rhythm. - [Narrator] Amazingly, it was the simplicity of this keying system, which made it much faster than any of the buttons and cranks employed by the needle telegraphs in Europe. The letter rate jumped to 135 letters per minute or more with trained operators. And on May 24th, 1844, the first successful transmission was the message, what hath God wrought. And the next day it was reported by the New York Tribune. That quote, "the miracle of annihilation of space "is at length performed." Consider that at the time 90% of messages were still transported by horseback. Immediately, this technology was becoming critical to the success of military newspapers, financial traders, crime fighting, any business that relied on information now relied on the telegraph and Morse code. By 1900, the prices had dropped to 30 cents per message, as traffic surged to over 63.2 million messages sent that year. As people began using this system, they naturally thought of ways to save money. This led to popular code books, that mapped words to common sentences. For example, blade would actually mean please name and reserve for myself and family the following accommodations. The telegraph companies frowned upon this as they were happily charging people to be verbose, more letters equals more profit. It was now clear that information was an elastic term and a specific meaning was needed. And obvious question remained unanswered, if you are selling information, no matter the system, how should you quantify it to be fair to everyone? Number of letters as a measure of information would no longer suffice.