Morse Code

Operation of Morse Code

Using a telegraph key as the transmitter device, an operator sends out messages based on short signals—the dots—combined in sequence with longer signals—the dashes. On the other end, an electromagnetic device would receive the signals, and the receiving operator would write down the transmitted letters and numbers to form a communicative text. In the 19th century, the receiving device made a click noise, which the receiving operator would transcribe into the communicative text.

In U.S. amateur radio, an operator has a “handle” that corresponds to his or her license from the Federal Communications Commission. This license name, or call letters, might be WN4CRZ. The telegraph operator, using wireless continuous wave transmission, would key the following for his or her handle: dot-dash-dash, dash-dot, dot-dot-dot-dot-dash, dash-dot-dash-dot, dot-dash-dot, and dash-dash-dot-dot. There would be a short space—silence—between each character transmitted, and slightly longer space between words. The handle, or call letters, is unique to each operator. In the example, the “N” represents the level of license (novice) and the 4 stands for the region of the United States where the operator resided (Southeast). Another operator would respond with his or her own handle, and an amateur radio interpersonal conversation would begin over the radio waves. Before radio transmission, Morse code would be transmitted with wired telegraph, which required the building of lines, usually along railroad tracks in the 19th century.

In technical terms, Morse code occurs by connecting the current when the telegraph key is pressed down, forming a circuit. Turning the key off—that is, having the points on the key separate—disengages the circuit. The current or wave that carries the dot or dash occurs when the key is struck down. The grammar of Morse code was based on the relative usage of a letter, so that “E,” the most commonly used English letter, has the shortest transmission duration, which is a single dot. Much less frequently used “Q” has a longer duration: dash-dash-dot-dash. Morse code’s grammar was also based on long held practices in visual signal messaging, including the flag-based semaphore system—long part of military operations in Europe.

Development of Morse Code

The code is named for artist Samuel F. B. Morse, one of the North American inventors of the telegraph. Morse made his telegraphy invention along with physicist Joseph Henry and machinist Alfred Vail. With a $30,000 internal improvements grant from Congress, Morse and Vail built a telegraph line stretching 40 miles along the railroad between Baltimore, Maryland, and Washington, DC, in 1844 after having received a patent for their telegraphic apparatus from the U.S. government. Morse and Vail would be the operators during the first official transmission of the Morse telegraphy from Washington to Baltimore on May 24, 1844. On May 1, Vail had transmitted from about halfway up the line to Baltimore back to Washington a message that the Whig Party had nominated Henry Clay for president; that transmission got to Washington 70 minutes before a train-delivered message did.

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