Short, long and silence
International Morse code represents characters with patterns of short and long signals, conventionally written as dots and dashes. The pauses help separate the parts of the message.
The International Telecommunication Union sets out the characters and timing. Begin with two short examples: the letter E is one dot; the letter T is one dash.
Order changes the letter
The letter A is a dot followed by a dash. Reverse their order—a dash followed by a dot—and you have N.
Imagine tapping the rhythm slowly on a desk. A short signal followed by a long one is a different pattern from a long signal followed by a short one. Counting two signals is not enough; their order matters.
Give the gaps their space
Use one dot as your timing unit. A dash lasts three units. The gap between signals within one letter lasts one unit; the gap between letters lasts three units; the gap between words lasts seven units.
To send A then E, you need a dot, a one-unit gap, a dash, a three-unit letter gap, then a dot. Without the longer letter gap, the listener would not know where the first character ended.
Compare two kinds of pattern
A QR code arranges information across a grid. This Morse example arranges signals in time. In both cases, the reader needs the convention that gives the pattern meaning.
Return to Read the codes around you to compare a product number, its check digit, a QR grid and a timed signal. The short quiz is optional.