Radio Telegraphy Signal Transmitted Across Atlantic

Wireless telegraphy or radiotelegraphy is the transmission of text messages by radio waves, analogous to electrical telegraphy using cables.^¹ Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires.^¹ In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code.^¹ In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves.^¹ At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code.^¹