Wireless telegraphy in the context of Wireless communication

Wireless communication (or just wireless, when the context allows) is the transfer of information (telecommunication) between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most common wireless technologies use radio waves. With radio waves, intended distances can be short, such as a few meters for Bluetooth, or as far as millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mice, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications involve other electromagnetic phenomena, such as light and magnetic or electric fields, or the use of sound.

The term wireless has been used twice in communications history, with slightly different meanings. It was initially used from about 1890 for the first radio transmitting and receiving technology, as in wireless telegraphy, until the new word radio replaced it around 1920. Radio sets in the UK and the English-speaking world that were not portable continued to be referred to as wireless sets into the 1960s. The term wireless was revived in the 1980s and 1990s mainly to distinguish digital devices that communicate without wires, such as the examples listed in the previous paragraph, from those that require wires or cables. This became its primary usage in the 2000s, due to the advent of technologies such as mobile broadband, Wi-Fi, and Bluetooth.

Guglielmo Giovanni Maria Marconi, 1st Marquess (/mɑːrˈkoʊni/ mar-KOH-nee; Italian: [ɡuʎˈʎɛlmo marˈkoːni]; 25 April 1874 – 20 July 1937), was an Italian radio-frequency engineer, inventor, and politician known for his creation of a practical radio wave-based wireless telegraph system. This led to him being largely credited as the inventor of radio and sharing the 1909 Nobel Prize in Physics with Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy."His work laid the foundation for the development of radio, television, and all modern wireless communication systems.

As an entrepreneur and a businessman, Marconi founded the Marconi Company in the United Kingdom in 1897. In 1929, he was ennobled as a marquess (Italian: marchese) by Victor Emmanuel III. In 1931, he set up Vatican Radio for Pope Pius XI.

A telegraph key, clacker, tapper or morse key is a specialized electrical switch used by a trained operator to transmit text messages in Morse code in a telegraphy system. Keys are used in all forms of electrical telegraph systems, including landline (also called wire) telegraphy and radio (also called wireless) telegraphy. An operator uses the telegraph key to send electrical pulses (or in the case of modern CW, unmodulated radio waves) of two different lengths: short pulses, called dots or dits, and longer pulses, called dashes or dahs. These pulses encode the letters and other characters that spell out the message.

A Tesla coil is an electrical resonant transformer device designed by inventor Nikola Tesla in 1891. It is used to produce high voltage, low current, high frequency alternating current. Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits.

Tesla used these devices to conduct innovative experiments in electrical lighting, phosphorescence, X-ray generation, high-frequency alternating current phenomena, electrotherapy, and the wireless transmission of electrical energy. Tesla coil circuits were used commercially in spark-gap transmitters for wireless telegraphy until the 1920s, and in medical equipment such as electrotherapy and violet ray devices. Today, their main usage is for entertainment and educational displays, although small coils are still used as leak detectors for high-vacuum systems.

A telegraphist (British English), telegrapher (American English), or telegraph operator is a person who uses a telegraph key to send and receive Morse code messages in a telegraphy system. These messages, also called telegrams, can be transmitted electronically by land lines, or wirelessly by radio.

The siege of Toma was a bloodless action during the First World War on the island of New Pomerania (now New Britain) between 14 and 17 September 1914 as part of the occupation of German New Guinea by the Australian Naval and Military Expeditionary Force (AN&MEF). Australian forces had been dispatched to seize and destroy German wireless stations in the south-west Pacific because they were used by the German East Asian Cruiser Squadron of Vice Admiral Maximilian von Spee which threatened merchant shipping in the region. New Zealand provided a similar force for the occupation of German Samoa. Ultimately the German colonial government was forced to surrender after being surrounded, ending the last significant resistance in the territory.

RMS Titanic sank on 15 April 1912 in the North Atlantic Ocean. The largest ocean liner in service at the time, Titanic was four days into her maiden voyage from Southampton, England, to New York City, United States, with an estimated 2,224 people on board when she struck an iceberg at 23:40 (ship's time) on 14 April. She sank two hours and forty minutes later at 02:20 ship's time (05:18 GMT) on 15 April, resulting in the deaths of up to 1,635 people, making it one of the deadliest peacetime maritime disasters in history.

Titanic received six warnings of sea ice on 14 April, but was travelling at a speed of roughly 22 knots (41 km/h) when her lookouts sighted the iceberg. Unable to turn quickly enough, the ship suffered a glancing blow that buckled the steel plates covering her starboard side and opened six of her sixteen compartments to the sea. Titanic had been designed to stay afloat with up to four of her forward compartments flooded, and the crew used distress flares and radio (wireless) messages to attract help as the passengers were put into lifeboats.

A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particle accelerator having a continuous output, as opposed to a pulsed output.

By extension, the term continuous wave also refers to an early method of radio transmission in which a sinusoidal carrier wave is switched on and off. This is more precisely called interrupted continuous wave (ICW). Information is carried in the varying duration of the on and off periods of the signal, for example by Morse code in early radio. In early wireless telegraphy radio transmission, CW waves were also known as "undamped waves", to distinguish this method from damped wave signals produced by earlier spark gap type transmitters.

The Battle of Tsushima (Russian: Цусимское сражение, Tsusimskoye srazheniye, Japanese: 日本海海戦, Nihonkai kaisen) was the final naval battle of the Russo-Japanese War, fought on 27–28 May 1905 in the Tsushima Strait. A devastating defeat for the Imperial Russian Navy, the battle was the only decisive engagement ever fought between modern steel battleship fleets and the first in which wireless telegraphy (radio) played a critically important role. The battle was described by contemporary Sir George Clarke as "by far the greatest and the most important naval event since Trafalgar". The battle is also known in Japan as the Battle of the Sea of Japan.

The battle involved the Japanese Combined Fleet under Admiral Tōgō Heihachirō and the Russian Second Pacific Squadron under Admiral Zinovy Rozhestvensky, which had sailed over seven months and 18,000 nautical miles (33,000 km) from the Baltic Sea. The Russians hoped to reach Vladivostok and establish naval control of the Far East in order to relieve the Imperial Russian Army in Manchuria. The Russian fleet had a large advantage in the number of battleships, but was overall older and slower than the Japanese fleet, and outnumbered nearly three to one in total hulls. The Russians were sighted in the early morning on 27 May, and the battle began in the afternoon. Rozhestvensky was wounded and knocked unconscious in the initial action, and four of his battleships were sunk by sunset. At night, Japanese destroyers and torpedo boats attacked the remaining ships, and Admiral Nikolai Nebogatov surrendered in the morning of 28 May.

A spark-gap transmitter is an obsolete type of radio transmitter which generates radio waves by means of an electric spark. Spark-gap transmitters were the first type of radio transmitter, and were the main type used during the wireless telegraphy or "spark" era, the first three decades of radio, from 1887 to the end of World War I. German physicist Heinrich Hertz built the first experimental spark-gap transmitters in 1887, with which he proved the existence of radio waves and studied their properties.

A fundamental limitation of spark-gap transmitters is that they generate a series of brief transient pulses of radio waves called damped waves; they are unable to produce the continuous waves used to carry audio (sound) in modern AM or FM radio transmission. So spark-gap transmitters could not transmit audio, and instead transmitted information by radiotelegraphy; the operator switched the transmitter on and off with a telegraph key, creating pulses of radio waves to spell out text messages in Morse code.

The Women's Royal Australian Naval Service (WRANS) was the women's branch of the Royal Australian Navy (RAN). In 1941, fourteen members of the civilian Women's Emergency Signalling Corps (WESC) were recruited for wireless telegraphy work at the Royal Australian Navy Wireless/Transmitting Station Canberra, as part of a trial to free up men for service aboard ships. Although the RAN and the Australian government were initially reluctant to support the idea, the demand for seagoing personnel imposed by the Pacific War saw the WRANS formally established as a women's auxiliary service in 1942. The surge in recruitment led to the development of an internal officer corps. Over the course of World War II, over 3,000 women served in the WRANS.

The organisation was disbanded in 1947, but was reestablished in 1951 in response to the manpower demand caused by Cold War commitments. In 1959, the WRANS was designated a permanent part of the Australian military. The WRANS continued to operate until 1985, when female personnel were integrated into the RAN.

The Samoa Expeditionary Force (SEF) was a small volunteer force of approximately 1,400 men raised in New Zealand shortly after the outbreak of World War I to seize and destroy the German wireless station in German Samoa in the south-west Pacific. Britain required the German wireless installations to be destroyed because they were used by Vizeadmiral (Vice Admiral) Maximilian von Spee's East Asia Squadron of the Imperial German Navy, which threatened merchant shipping in the region. Following the capture of German possessions in the region, the SEF provided occupation forces for the duration of the war. Australia provided a similar force for the Allied occupation of German New Guinea.

Fish (sometimes capitalised as FISH) was the UK's GC&CS Bletchley Park codename for any of several German teleprinter stream ciphers used during World War II. Enciphered teleprinter traffic was used between German High Command and Army Group commanders in the field, so its intelligence value (Ultra) was of the highest strategic value to the Allies. This traffic normally passed over landlines, but as German forces extended their geographic reach beyond western Europe, they had to resort to wireless transmission.

Bletchley Park decrypts of messages enciphered with the Enigma machines revealed that the Germans called one of their wireless teleprinter transmission systems "Sägefisch" ('sawfish') which led British cryptographers to refer to encrypted German radiotelegraphic traffic as "Fish." The code "Tunny" ('tuna') was the name given to the first non-Morse link, and it was subsequently used for the Lorenz SZ machines and the traffic enciphered by them.

The Fleming valve, also called the Fleming oscillation valve, is a thermionic valve or vacuum tube invented in 1904 by English physicist John Ambrose Fleming as a detector for early radio receivers used in electromagnetic wireless telegraphy. It was the first practical vacuum tube and the first thermionic diode, a vacuum tube whose purpose is to conduct current in one direction and block current flowing in the opposite direction. The thermionic diode was later widely used as a rectifier — a device that converts alternating current (AC) into direct current (DC) — in the power supplies of a wide range of electronic devices, until beginning to be replaced by the selenium rectifier in the early 1930s and almost completely replaced by the semiconductor diode in the 1960s. The Fleming valve was the forerunner of all vacuum tubes, which dominated electronics for 50 years. The IEEE has described it as "one of the most important developments in the history of electronics", and it is on the List of IEEE Milestones for electrical engineering.