1837, the American inventor S. Morse invented the telegraph and developed a set of codes consisting of periods and dashes. 1844 On May 24th, the telegraph was successfully transmitted for the first time in the world, and then the telegraph service from new york to Baltimore to Washington was opened. By 185 1, the telegraph has connected all the big cities in the United States. At the beginning of the 20th century, with the invention of radio, Morse code began to resound through space. Soon, SOS, a distress signal composed of Morse code, was born, replacing the original CQD (Come on, Danger) of 1908, and it was officially put into use.
It is generally believed that SOS means "saving lives", "saving ships" or "stopping other signals", but this is not the case. The letter combination SOS has no explanation. They are the simplest, fastest and clearest Morse code combinations selected by the members of the International Radiotelephone Conference-3 periods, 3 dashes and 3 periods. After that, 48 times a day and night, that is, twice an hour (15 to 18 and 45 to 48), the space was quiet for 3 minutes. At this time, all signals should be interrupted, even if it is only half a sentence, radio operators all over the world will adjust the frequency to SOS band-500 Hz, waiting for the emergence of distress signals. 191April 14, the Titanic was wrecked on the high seas, and the SOS distress signal was sent for the first time. Unfortunately, another ship that was sailing in the distress signal area was missed because the operator temporarily left his post. But there is no doubt that in the next 90 years, it is because of the use of simple Morse code that SOS saved countless lives.
In fact, the signals indicating "emergency help" in radio communication are three short, three long and three short. Because three short symbols in Morse code stand for S and three long symbols stand for O, the emergency distress signal is called SOS for short. Because this signal is simple and clear, it is adopted by all countries in the world. Now, whether it is a ship or an airplane, you can use SOS for help when you are in danger. After receiving this signal, anyone and any country have the obligation to go to the rescue, which has become an international practice, but generally the letters SOS should be capitalized.