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High-frequency direction finding, usually known by its abbreviation HF/DF or nickname huff-duff, is a type of radio direction finder (RDF) introduced in World War II. High frequency (HF) refers to a radio band that can effectively communicate over long distances; for example, between U-boats and their land-based headquarters.
Direction finding ( DF ), or radio direction finding ( RDF ), is the use of radio waves to determine the direction to a radio source. The source may be a cooperating radio transmitter or may be an inadvertant source, a naturally-occurring radio source, or an illicit or enemy system.
Radar beacon. Racon signal as seen on a radar screen. This beacon receives using sidelobe suppression and transmits the letter "Q" in Morse code near Boston Harbor (Nahant) 17 January 1985. Radar beacon (short: racon) is – according to article 1.103 of the International Telecommunication Union's (ITU) ITU Radio Regulations (RR) [1 ...
Doppler radio direction finding. Doppler radio direction finding, also known as Doppler DF, is a radio direction finding method that generates accurate bearing information with a minimum of electronics. It is best suited to VHF and UHF frequencies and takes only a short time to indicate a direction. This makes it suitable for measuring the ...
An automatic direction finder (ADF) is a marine or aircraft radio-navigation instrument that automatically and continuously displays the relative bearing from the ship or aircraft to a suitable radio station.
The International Radiotelephony Spelling Alphabet or simply Radiotelephony Spelling Alphabet, commonly known as the NATO phonetic alphabet, is the most widely used set of clear-code words for communicating the letters of the Roman alphabet. Technically a radiotelephonic spelling alphabet, it goes by various names, including NATO spelling ...
ISO 3166-1 (Codes for the representation of names of countries and their subdivisions – Part 1: Country codes) is a standard defining codes for the names of countries, dependent territories, and special areas of geographical interest.
A stereoscopic rangefinder or stereoscopic telemeter [1] is an optical device that measures distance from the observer to a target, using the observer's capability of binocular vision. It looks similar to a coincidence rangefinder, which uses different principles and has only one eyepiece.
A Bellini–Tosi direction finder ( B–T or BTDF) is a type of radio direction finder (RDF), which determines the direction to, or bearing of, a radio transmitter. Earlier RDF systems used very large rotating loop antennas, which the B–T system replaced with two fixed antennae and a small rotating loop, known as a radiogoniometer.
A wiggler, also known as a wobbler, edge-finder, center-finder or laser-centering-device, is a tool used with a machine like a mill, to accurately align the machine head with the work prior to machining.