S in Morse Code
S is ... - di-di-dit, 5 units, 300 milliseconds at 20 words per minute.
At this speed the screen flashes more than three times per second. If you are sensitive to flashing light, set the speed to 7 WPM or lower.
Advanced settings
...
Press play in the box above - S is already in it.
How long S takes
S is 3 dots and 0 dashes. With the gaps that comes to 5 units, number 6 of 26 by length.
- 5 WPM: 1,200 ms
- 13 WPM: 462 ms
- 20 WPM: 300 ms
The arithmetic behind them is on the timing page.
What S gets confused with
6 characters sit one element away from S, more than most letters manage:
- D
-..- a dash in first place instead of a dot - H
....- one more dot on the end - I
..- the last dot missing - R
.-.- a dash in second place instead of a dot - U
..-- a dash in third place instead of a dot - V
...-- one more dash on the end
S in the tree
- Built from:
.= E and..= I, then... - Carries on into: H and V (2 of the 26)
- Backwards:
...= itself, a palindrome - Koch position: 4 of 26
The tree shows the whole shape, the trainer teaches it by ear.
Why S has this code
S makes up about 6.3 per cent of English text, which is number 7 of 26 by frequency, against number 6 by length. Close enough that the code is doing its job for this letter.
The lengths were set by counting, not by theory - the alphabet page has that story.
Worth knowing about S
SOS opens and closes with it, and the S in an RST report stands for strength. Three dots is one of the few patterns most people recognise without having learnt the code.
Frequently asked questions
-
What is S in Morse code?
...- 3 dots and 0 dashes, spoken di-di-dit. -
How long does S take to send?
5 units: 300 milliseconds at 20 words per minute, 1,200 at 5.
-
Which letters sound like S?
D, H, I, R, U and V - each one element away from
....