The Q code is a standardized collection of three-letter message encodings, all starting with the letter "Q", initially developed for commercial radiotelegraph communication, and later adopted by other radio services, especially amateur radio. 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 have often been limited to restrict ones starting with "Q" or having an embedded three-letter Q sequence. Telegraphy (from the Greek words tele = far away and grapho = write) is the long distance transmission of written messages without physical transport of letters, originally over wire. ... Amateur radio, often called ham radio, is a hobby and public service enjoyed by about 3 million people[1] throughout the world. ... 1922 Chart of the Morse Code Letters and Numerals Morse code is a method for transmitting information, using standardized sequences of short and long marks or pulses — commonly known as dots and dashes — for the letters, numerals, punctuation and special characters of a message. ... Call sign can refer to different types of call signs: Airline call sign Aviator call sign Cosmonaut call sign Radio and television call signs Tactical call sign, also known as a tactical designator See also: International Callsign Allocations, Maritime Mobile Service Identity This is a disambiguation page — a navigational...

Early developments

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 Third International Radiotelegraph Convention. (This Convention, which met in London, was signed on July 5, 1912, and became effective July 1, 1913.) July 5 is the 186th day of the year (187th in leap years) in the Gregorian Calendar, with 179 days remaining. ... 1912 (MCMXII) was a leap year starting on Monday in the Gregorian calendar (or a leap year starting on Tuesday in the 13-day-slower Julian calendar). ... July 1 is the 182nd day of the year (183rd in leap years) in the Gregorian Calendar, with 183 days remaining. ... 1913 (MCMXIII) was a common year starting on Wednesday. ...

The codes in the range QAA-QNZ are reserved for aeronautical use; QOA-QOZ for maritime use, and QRA-QUZ for all services.

The following table reviews a sample of the all-services Q codes adopted by the 1912 Convention:

First Twelve Q Codes Listed in the 1912 International Radiotelegraph Convention Regulations

Later usage

Over the years, modifications were made to the original Q codes to reflect changes in radio practice. In the original international list, QSW/QSX stood for "Shall I increase/decrease my spark frequency?", however, spark-gap transmitters were banned in the United States in the 1920s, rendering the original meaning of those Q codes obsolete. Other Q codes have been introduced, especially those for amateur radio usage. A typical spark transmitter circuit. ...

Some Q codes are also used in aviation, in particular QNH and QFE, referring to certain altimeter settings. These codes are used in radio conversations with air traffic control as unambiguous shorthand, where safety and efficiency are of vital importance. A subset of Q codes is used by Dade County, Florida law enforcement, one of the few instances where Q codes are used in ground voice communication. Aviation refers to flying using aircraft, machines designed by humans for atmospheric flight. ... QNH is a Q code. ... QFE is a three letter acronym which can have meanings in aviation, in software development, and in internet usage. ... Air Traffic Control Towers (ATCTs) at Amsterdams Schiphol Airport (Netherlands) Air traffic control (ATC) is a service provided by ground-based controllers who direct aircraft on the ground and in the air. ... County slogan: Delivering Excellence Every Day Location of county in the state of Florida County Seat Miami, Florida Area  - Total  - Water 6,297 km² (2,431 mi²) 1,257 km² (485 mi²) 19. ...

Many military and other organizations that use Morse code have adopted additional codes, including the Z code used by most European and NATO countries. The Z code adds commands and questions adapted for military radio transmissions. For example, "ZBW 2" — change to backup frequency number 2 — or "ZNB abc" — my checksum is abc, what is yours? In most military Morse code transmissions, freeform text is strictly forbidden, and all communication must be accomplished using three-letter abbreviations, the Q and Z code. For the virtual machine language introduced by Infocom, see the article under Z-machine. ... NATO 2002 Summit in Prague The North Atlantic Treaty Organisation[1] (NATO), also called the North Atlantic Alliance, the Atlantic Alliance or the Western Alliance, is an international organisation for collective security established in 1949, in support of the North Atlantic Treaty signed in Washington, DC, on 4 April 1949. ...

Used in their formal "question/answer" sense, the meaning of a Q code varies depending on whether or not the individual Q code is sent as a question or an answer. For example, the message "QRP?" means "Shall I decrease transmitter power?", and a reply of "QRP" means "Yes, decrease your transmitter power". This structured use of Q codes is fairly rare and now mainly limited to amateur radio and military morse code (CW) traffic networks.

Amateur radio

Selected Q codes were soon adopted by amateur radio operators. In December, 1915 the American Radio Relay League began publication of a magazine titled QST, named after the Q code for "General call to all stations". In amateur radio, the Q codes are more commonly used as shorthand nouns, verbs, or adjectives. For example, an amateur radio operator will complain about QRM (man-made interference), or tell another operator that there is "QSB on the signal"; "to QSY" is to change your operating frequency. An amateur radio operator An amateur radio operator is an individual who has been assigned an amateur radio license by a governmental regulatory authority. ... The ARRL Logo. ...

The following table gives the most common Q codes used in amateur radio:

Q Codes Commonly Used by Radio Amateurs

Some of these common usages vary somewhat from their formal, official sense. There are also a few unofficial and humorous codes in use, such as QLF ("try sending with your LEFT foot") and QSC ("send cigarettes", not the official meaning of "this is a cargo vessel"). In the question form, QNB?, is supposed to mean "How many buttons does your radio have?" A reply of the form QNB 45/15 means "45, and I know what 15 of them do." 1922 Chart of the Morse Code Letters and Numerals Morse code is a method for transmitting information, using standardized sequences of short and long marks or pulses — commonly known as dots and dashes — for the letters, numerals, punctuation and special characters of a message. ... QRO In amateur radio, a Q code meaning increase power level. The opposite of QRP. In modern ham radio use, QRO is synonymous with high power. The typical station transmitter for high frequency use has 100 watts output. ... In amateur radio, QRP operation means transmitting at reduced power levels. ... The American Radio Relay League (ARRL) was founded in May 1914 by Hiram Percy Maxim. ... A 1969 Radio Moscow QSL card QSL, or QSL card, is the confirmation of a QSO (a radio contact) between two radio amateurs. ... 1922 Chart of the Morse Code Letters and Numerals Morse code is a method for transmitting information, using standardized sequences of short and long marks or pulses — commonly known as dots and dashes — for the letters, numerals, punctuation and special characters of a message. ... 73 (seventy-three) is the natural number following 72 and preceding 74. ...

Some ham operators within the USA, particularly those travelling long distances, will monitor the National 2-meter[1] FM calling frequency of 146.520 MHz while in their vehicles. If you see a vehicle on the road with a bumper-sticker, license plate or other sign that says QRZ 52? and a few extra antennas, that is what's happening. The reason QRZ is used instead of the more correct QSX is that QSX is not normally used in voice communications while QRZ is used extensively.

Aviation

Although the majority of the Q codes have slipped out of common use, several remain part of the standard ICAO radiotelephony phraseology in aviation. The International Civil Aviation Organization (ICAO), an agency of the United Nations, develops the principles and techniques of international air navigation and fosters the planning and development of international air transport to ensure safe and orderly growth. ...

Altimeter Setting

QNH - sea level air pressure

QFE - air pressure at airfield elevation

QSL - used to verify time when communicating with TSC

e.g.

"Runway in use 22 lefthand, QFE 990 millibars."

"Request QNH"

Direction Finding

QDM - magnetic heading TO a station

QDR - magnetic heading FROM a station

QTE - True bearing FROM

QFU - The Runway in use

e.g.

"QDM QDM QDM (callsign) request QDR"

"Runway in use 22, QFU 22"

Radio Procedures

QSY - To freecall another frequency. (This is not an official part of the standard phraseology any more but is still regularly heard)

External links

• Handbook for Wireless Telegraph Operators, October, 1909.
• Radio Laws and Regulations of the United States: Edition July 27, 1914. (Includes the 1912 London Radiotelegraphic Convention)
• ARRL amateur radio Q signals
• ITU Q code table for the maritime mobile service
• List of Q codes