Codes used today: Morse code, semaphore, binary code.
Thursday 10th December 2020 LO: understanding codes in use today Thousands of years ago the Chinese developed a system of conveying informa on using twigs that were either broken or whole. It was wri en down as either broken or unbroken lines.
It was a form of ‘binary code’. ‘Binary’ means ‘two’ – so in binary code there are only two op ons, like yes and no, or black and white, or broken and not-broken. The same idea is used today in computers. It is how computers send, receive and store informa on: music, films, pictures, phone calls, games, everything!
01001000 01100101 01101100 01101100 01101111 00100001
These ones and zeros are binary code for ‘Hello!’ Any code that uses just two symbols to represent informa on is a binary code.
In 1937, the American mathema cian Claude Shannon realized that the simple ON / OFF of an electric switch could be a binary code. 01001000 01100101 01101100 01101100 01101111
Computers are just a huge number of switches flicking on and off, millions of mes a second.
Use the key below to write your own name in binary code.
You can see how difficult binary code is for us to read! And how different we are from computers! Computers don’t get red or bored – they just do as they’re told. Signals some mes need to be very clear and simple.
Traffic lights are a code: green, amber and red.
Railways signals work in the same way: STOP / CAUTION / GO. 200 years ago people knew they needed a faster way to send messages. In 1792, the French inventor Claude Chappe developed the op cal telegraph.
An op cal telegraph is a line of towers, each a few miles apart. The signal operator in each tower passes the message on to the next.
That way a message could be sent faster than by a rider on horseback. The code used was called semaphore. Flag semaphore is s ll used by the U.S. Navy today. It is useful to communicate in very noisy environments, like on aircra carriers. Try sending a short message to your friends! Maybe just signal ‘Help!’ It’s easy to get it wrong, because you have to think of the message from the other person’s point of view, not your own. The electric telegraph was invented in the 1840s. It was the first electronic communica ons system. Pulses of current were sent down wires. Each pulse could be part of a code for a le er. Telegraph poles and wires became a common sight. The American inventor Samuel Morse developed a code for the telegraph that is s ll used in communica ons today.
Morse Code is a series of dots (short signals) and dashes (longer signals).
Telegraph operators had to tap out each le er of a message. Try sending a message in Morse Code.
Morse Code is useful because it can be transmi ed in different ways – as an electric signal, as sounds, or as flashes of light.
The ‘dashes’ are long sounds or long flashes. The ‘dots’ are short sounds or short flashes.
This is a sailor in the U.S. Navy sending a Morse Code signal from one ship to another.
Why might they use light instead of other methods of communica on? When the Titanic sank in 1912, the telegraph operator sent desperate Morse Code messages for help. ‘SOS’ in Morse Code is the interna onal distress signal. See if you can spot SOS in the clip below. h ps://www.youtube.com/watch?v=snkwsU98QlQ Imagine you are on board the Titanic, and the ship is sinking. In your work books, write a short sentence calling the coastguard for help.
Translate the message into the three codes we’ve looked at: 1. binary code 2. flag semaphore (draw s ck figures to spell out the words). 3. Morse Code.
Label each coded message, saying which code you’ve used..