Q code

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. To distinguish the use of a Q-code transmitted as a question from the same Q-code transmitted as a statement, operators either prefixed it with the military network question marker "" (dit dit dah dit dah) or suffixed it with the standard Morse question mark (dit dit dah dah dit dit). Although Q-codes were created when radio used Morse code exclusively, they continued to be employed after the introduction of voice transmissions. To avoid confusion, transmitter call signs are restricted; no country is ever issued an ITU prefix starting with "Q". Codes in the range QAA–QNZ are reserved for aeronautical use; QOA–QQZ for maritime use and QRA–QUZ for all services. "Q" has no official meaning, but it is sometimes assigned a word with mnemonic value, such as "Queen" for example in QFE: Queen's field elevation, or "Query", "Question", "reQuest". The original Q-codes were created, circa 1909, by the British government as a "List of abbreviations ... prepared for the use of British ships and coast stations licensed by the Postmaster General". The Q-codes facilitated communication between maritime radio operators speaking different languages, so they were soon adopted internationally. A total of forty-five Q-codes appeared in the "List of Abbreviations to be used in Radio Communications", which was included in the Service Regulations affixed to the Second International Radiotelegraph Convention in London (The Convention was signed on July 5, 1912, and became effective July 1, 1913.) The following table reviews a sample of the all-services Q-codes adopted by the 1912 convention: Over the years the original Q-codes were modified to reflect changes in radio practice. For example, QSW / QSX originally stood for, "Shall I increase / decrease my spark frequency?", but in the 1920s spark-gap transmitters were gradually being banned from land stations, making that meaning obsolete.