Published by Australian Academy of Science
Activity 3 | Communicating with light – fibre optics

Morse code

1. Computers use only two numbers in their communication system, 1 and 0. This is called a binary or base-two numbering system.
   • Working with a partner, try to devise binary code (1 and 0, or on and off) to send a simple message.

   • Write down why you had difficulty in sending a binary code.

2. Morse code is a system of dots, dashes and spaces to represent the letters of the alphabet. It is used in telegraphy and signalling.

   A

   Alpha

   .-

   B

   Bravo

   -

   C

   Charlie

   -.-.

   D

   Delta

   -..

   E

   Echo

   .

   F

   Foxtrot

   ..-.

   G

   Golf

   - -.

   H

   Hotel

   ....

   I

   India

   ..

   J

   Juliet

   . – - -

   K

   Kilo

   - . -

   L

   Lima

   .-..

   M

   Mike

   - -

   N

   November

   -.

   O

   Oscar

   - – -

   P

   Papa

   .- -.

   Q

   Quebec

   - -.-

   R

   Romeo

   .-.

   S

   Sierra

   ...

   T

   Tango

   -

   U

   Uniform

   ..-

   V

   Victor

   ...-

   W

   Whisky

   .- -

   X

   X-ray

   -..-

   Y

   Yankee

   -.- -

   Z

   Zulu

   - -..

   • Use Morse code to send a simple message to your partner.

   • Write down why Morse code is easier for people to use than a simple binary system of 1 and 0.

Teachers notes

1. It is difficult and laborious for us to communicate using a binary code. We can't easily identify a sequence of consecutive zeros or consecutive ones because we don't have an accurate enough inbuilt sense of time. It is possible to devise a binary code to eliminate this problem but it is generally not very efficient. For example, we could always send a 0 after each 1, and have a large number of zeroes (eg, five) between symbols. Then we could identify each letter of the alphabet by a specified number of 'dots' (each a 1, 0 sequence).

2. Morse code is easier than the simple binary system because it uses two active symbols, a dot and a dash. Also the simple dot-dash of 'A' is much simpler than its binary equivalent.

You may want to point out that because of the ability of computers to handle simple codes at very high speed, they are able to communicate in a very different way from humans.