What do you mean by three long and three short in the distress signal?

The signal of "emergency help" is three short, three long and three short.

Use Morse code to express the international distress signal SOS: S is three short, O is three long, and the complete expression is: drip, drip, drip, drip, drip, drip, drip, drip, so you only need to type the signal "three short, three long, three short", which means calling for help.

Another expression of SOS is 19 15 19. 19, 15 and 19 are the order of s, o and s in the 26 English letters respectively. The reason is that SOS distress signals are widely known. In extremely passive situations, SOS will expose the victims' distress information, so 19 15 19 is another obscure symbol for transmitting and expressing distress information.