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Radio frequency ( RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency [1] range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies, and also ...
Japanese naval codes. The vulnerability of Japanese naval codes and ciphers was crucial to the conduct of World War II, and had an important influence on foreign relations between Japan and the west in the years leading up to the war as well. Every Japanese code was eventually broken, and the intelligence gathered made possible such operations ...
Guglielmo Giovanni Maria Marconi, 1st Marquis of Marconi FRSA GCVO (Italian: [ɡuʎˈʎɛlmo marˈkoːni]; 25 April 1874 – 20 July 1937) was an Italian inventor, electrical engineer,and politician, known for his creation of a practical radio wave–based wireless telegraph system.
The codes' procedure words, a type of voice procedure, are designed to convey complex information with a few words, when brevity is required but security is not. Ten-code, North American police brevity codes, including such notable ones as 10-4. Phillips Code. NOTAM Code. Wire signal, Morse Code abbreviation, also known as 92 Code.
Crystal radio was invented by a long, partly obscure chain of discoveries in the late 19th century that gradually evolved into more and more practical radio receivers in the early 20th century. The earliest practical use of crystal radio was to receive Morse code radio signals transmitted from spark-gap transmitters by early amateur radio ...
A French ship-to-shore radio station in 1904. The invention of radio communication was preceded by many decades of establishing theoretical underpinnings, discovery and experimental investigation of radio waves, and engineering and technical developments related to their transmission and detection. These developments allowed Guglielmo Marconi ...
Hospital emergency codes are coded messages often announced over a public address system of a hospital to alert staff to various classes of on-site emergencies. The use of codes is intended to convey essential information quickly and with minimal misunderstanding to staff while preventing stress and panic among visitors to the hospital.
25 October 1944. ( 1944-10-25) Radio Londres ( [ʁa.djo lɔ̃dʁ], French for "Radio London") was a radio station broadcast from 1940 to 1944 by the BBC in London to Nazi-occupied France. It was entirely in French and was operated by the Free French who had escaped from occupied France. It served not only to counter the propaganda broadcasts of ...