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The Q-code is a standardised collection of three-letter codes that each start with the letter "Q". It is an operating signal initially developed for commercial radiotelegraph communication and later adopted by other radio services, especially amateur radio.
The Maidenhead Locator System (a.k.a. QTH Locator and IARU Locator) is a geocode system used by amateur radio operators to succinctly describe their geographic coordinates, which replaced the deprecated QRA locator, which was limited to European contacts. [1]
The QRA locator, also called QTH locator in some publications, is an obsolete geographic coordinate system used by amateur radio operators in Europe before the introduction of the Maidenhead Locator System. As a radio transmitter or receiver location system the QRA locator is considered defunct, but may be found in many older documents.
The QSK code is one of the earliest signal reporting formats and is a part of the Q code used for commercial radiotelegraph communication, appearing as one of the twelve Q Codes listed in the 1912 International Radiotelegraph Convention Regulations, and was later adopted by other radio services, especially amateur radio.
The Amateur radio R-S-T system signal report format currently in use was first developed in 1934. [citation needed] As early as 1943, the U.S and UK military published the first guidance that included the modern "Weak but readable", "Strong but distorted", and "Loud and clear" phrases. [citation needed]
An amateur radio license is valid only in the country where it is issued or in another country that has a reciprocal licensing agreement with the issuing country. [42] [43] In some countries, an amateur radio license is necessary in order to purchase or possess amateur radio equipment. [44]
Radio communications, prior to the advent of landlines and satellites as communication paths and relays, was always subject to unpredictable fade outs caused by weather conditions, practical limits on available emission power at the transmitter, radio frequency of the transmission, type of emission, type of transmitting antenna, signal waveform characteristics, modulation scheme in use ...
The consequences of overdiagnosis and overtreatment resulting from cancer screening can lead to a decline in quality of life, due to the adverse effects of unnecessary medication and hospitalization. [10] [12] [13] The accuracy of a cancer screening test relies on its sensitivity, and low sensitivity screening tests can overlook cancers. [10]