Wireless telegraphy

Wireless telegraphy transmits coded messages through electromagnetic waves rather than wires. Early systems used radio waves to send Morse code between stations.

Morse code: A system that represents letters and numbers as sequences of short and long signals. Its dots and dashes were the standard message code sent by early wireless stations.
James Clerk Maxwell: A Scottish physicist whose equations unified electricity and magnetism and predicted electromagnetic waves. His theory supplied the foundation for transmitting messages by electromagnetic waves.
Radio navigation: The use of radio signals to determine position, direction, or distance. Wireless transmissions enabled ships to obtain bearings and navigational guidance.
Electrical telegraph: A system that sends coded electrical signals between locations through conducting wires. It carries similar coded messages, but its signals travel along wires rather than through space.
Radio transmitter: An electronic device that generates and sends radio-frequency signals through an antenna. It converts telegraph signals into electromagnetic waves for transmission.
Heinrich Hertz: A German physicist who experimentally generated and detected electromagnetic waves in the 1880s. His experiments demonstrated the waves later used for wireless signaling.
Maritime distress signal: A standardized signal used to request urgent assistance at sea. Wireless telegraphy made distress calls possible beyond visual range.
Radio telephony: The transmission of speech by radio waves between stations. It replaces coded keying with voice as the primary transmitted message.
Spark-gap transmitter: A radio transmitter that creates electromagnetic waves using electrical sparks across a gap. This early transmitter produced the damped waves used in the first wireless telegraph systems.
Guglielmo Marconi: An Italian inventor and entrepreneur who developed practical long-distance wireless telegraphy. His systems turned laboratory radio experiments into commercial and maritime communication.

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