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The Q code is a standardized collection of three-letter message encodings, also known as a brevity code, all of which start 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 are restricted; while an embedded three-letter Q sequence may occur (for instance when requested by an amateur radio station dedicated to low-power operation), no country is ever issued an ITU prefix starting with "Q". The codes in the range QAA–QNZ are reserved for aeronautical use; QOA–QQZ for maritime use and QRA–QUZ for all services.

Early developments[edit]

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".[citation needed] 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 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:

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

Code Question Answer or Notice
QRA What ship or coast station is that? This is ____.
QRB What is your distance? My distance is ____.
QRC What is your true bearing? My true bearing is ____ degrees.
QRD Where are you bound for? I am bound for ____.
QRF Where are you bound from? I am bound from ____.
QRG What line do you belong to? I belong to the ____ Line.
QRH What is your wavelength in meters? My wavelength is ____ meters.
QRJ How many words have you to send? I have ____ words to send.
QRK How do you receive me? I am receiving (1-5) where 1 is unreadable and 5 is perfect.
QRL Are you busy? I am busy.
QRM Are you being interfered with? I am being interfered with.
QRN Are the atmospherics strong? Atmospherics are very strong.

Later usage[edit]

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. Over a hundred Q codes were listed in the Post Office Handbook for Radio Operators in the 1970s and cover subjects such as meteorology, radio direction finding, radio procedures, search and rescue, and so on.

Some Q codes are also used in aviation, in particular QNE, QNH and QFE, referring to certain altimeter settings. These codes are used in radiotelephone conversations with air traffic control as unambiguous shorthand, where safety and efficiency are of vital importance. A subset of Q codes is used by the Miami-Dade County, Florida local government for law enforcement and fire rescue communications, one of the few instances where Q codes are used in ground voice communication.[1]

The QAA–QNZ code range includes phrases applicable primarily to the aeronautical service,[2] as defined by the International Civil Aviation Organisation.[3] The QOA–QQZ code range is reserved for the maritime service. The QRA–QUZ code range includes phrases applicable to all services and is allocated to the International Telecommunications Union.[4] QVA–QZZ are not allocated.[5] Many codes have no immediate applicability outside one individual service, such as maritime operation (many QO or QU series codes) or radioteletype operation (the QJ series).[6]

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", which means "change to backup frequency number 2", and "ZNB abc", which means "my checksum is abc, what is yours?"[7]

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.

Breakdown by service[edit]

  • QAA to QNZ - Assigned by the International Civil Aviation Organization (ICAO).
  • QOA to QQZ - For the Maritime Services.
  • QRA to QUZ - Assigned by the International Telecommunications Union (ITU).

Amateur radio[edit]

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 were originally used in Morse code transmissions to shorten lengthy phrases and were followed by a Morse code question mark (‏·‏·‏—‏‏ —‏·‏·‏) if the phrase was a question.

Q codes are commonly used in voice communications as shorthand nouns, verbs, and adjectives making up phrases. For example, an amateur radio operator will complain about QRM (man-made interference), or tell another operator that there is "QSB on the signal" (fading); "to QSY" is to change your operating frequency, or to break in on a conversation QSK is often used even on VHF and UHF frequency's. (See also Informal usage, below.)

Q codes applicable for use in amateur radio[edit]

Code Question Answer or Statement
QLE What is your expected signal? The expected signal is low...
QRA What is the name (or call sign) of your station? The name (or call sign) of my station is ...
QRG Will you tell me my exact frequency (or that of ...)? Your exact frequency (or that of ... ) is ... kHz (or MHz).
QRH Does my frequency vary? Your frequency varies.
QRI How is the tone of my transmission? The tone of your transmission is (1. Good; 2. Variable; 3. Bad)
QRJ How many voice contacts do you want to make? I want to make ... voice contacts.
QRK What is the readability of my signals (or those of ...)? The readability of your signals (or those of ...) is ... (1 to 5).
QRL Are you busy? I am busy. (or I am busy with ... ) Please do not interfere.
QRM Do you have interference? I have interference.
QRN Are you troubled by static? I am troubled by static.
QRO Shall I increase power? Increase power.
QRP Shall I decrease power? Decrease power.
QRQ Shall I send faster? Send faster (... wpm)
QRS Shall I send more slowly? Send more slowly (... wpm)
QRT Shall I cease or suspend operation?/ shutoff the radio I am suspending operation. /shutting off the radio
QRU Have you anything for me? I have nothing for you.
QRV Are you ready? I am ready.
QRW Shall I inform ... that you are calling him on ... kHz (or MHz)? Please inform ... that I am calling him on ... kHz (or MHz).
QRX Shall I standby / When will you call me again? Please standby / I will call you again at ... (hours) on ... kHz (or MHz)
QRZ Who is calling me? You are being called by ... on ... kHz (or MHz)
QSA What is the strength of my signals (or those of ... )? The strength of your signals (or those of ...) is ... (1 to 5).
QSB Are my signals fading? Your signals are fading.
QSD Is my keying defective? Your keying is defective.
QSG Shall I send ... telegrams (messages) at a time? Send ... telegrams (messages) at a time.
QSK Can you hear me between your signals? I can hear you between my signals.
QSL Can you acknowledge receipt? I am acknowledging receipt.
QSM Shall I repeat the last telegram (message) which I sent you, or some previous telegram (message)? Repeat the last telegram (message) which you sent me (or telegram(s) (message(s)) numbers(s) ...).
QSN Did you hear me (or ... (call sign)) on .. kHz (or MHz)? I did hear you (or ... (call sign)) on ... kHz (or MHz).
QSO Can you communicate with ... direct or by relay? I can communicate with ... direct (or by relay through ...).
QSP Will you relay a message to ...? I will relay a message to ... .
QSR Do you want me to repeat my call? Please repeat your call; I did not hear you.
QSS What working frequency will you use? I will use the working frequency ... kHz (or MHz).
QST - Here is a broadcast message to all amateurs.
QSU Shall I send or reply on this frequency (or on ... kHz (or MHz))? Send or reply on this frequency (or on ... kHz (or MHz)).
QSW Will you send on this frequency (or on ... kHz (or MHz))? I am going to send on this frequency (or on ... kHz (or MHz)).
QSX Will you listen to ... (call sign(s) on ... kHz (or MHz))? I am listening to ... (call sign(s) on ... kHz (or MHz))
QSY Shall I change to transmission on another frequency? Change to transmission on another frequency (or on ... kHz (or MHz)).
QSZ Shall I send each word or group more than once? Send each word or group twice (or ... times).
QTA Shall I cancel telegram (message) No. ... as if it had not been sent? Cancel telegram (message) No. ... as if it had not been sent.
QTC How many telegrams (messages) have you to send? I have ... telegrams (messages) for you (or for ...).
QTH What is your position in latitude and longitude (or according to any other indication)? My position is ... latitude...longitude
QTR What is the correct time? The correct time is ... hours
QTU At what times are you operating? I am operating from ... to ... hours.
QTX Will you keep your station open for further communication with me until further notice (or until ... hours)? I will keep my station open for further communication with you until further notice (or until ... hours).
QUA Have you news of ... (call sign)? Here is news of ... (call sign).
QUC What is the number (or other indication) of the last message you received from me (or from ... (call sign))? The number (or other indication) of the last message I received from you (or from ... (call sign)) is ...
QUD Have you received the urgency signal sent by ... (call sign of mobile station)? I have received the urgency signal sent by ... (call sign of mobile station) at ... hours.
QUE Can you speak in ... (language), - with interpreter if necessary; if so, on what frequencies? I can speak in ... (language) on ... kHz (or MHz).
QUF Have you received the distress signal sent by ... (call sign of mobile station)? I have received the distress signal sent by ... (call sign of mobile station) at ... hours.

Informal usage[edit]

Chart of the Morse code letters and numerals.[8]

Some of the common usages of amateur radio codes, including in voice and writing, vary somewhat from their formal, official sense. Humorous and unofficial codes may be also be used.

QSK - "I can hear you during my transmission" - refers to a particular mode of Morse code operating in which the receiver is quickly enabled during the spaces between the dits and dahs, which allows another operator to interrupt transmissions. Many modern transceivers incorporate this function, sometimes referred to as full break-in as against semi-break-in in which there is a short delay before the transceiver goes to receive.[9]

QSY - "Change to transmission on another frequency"; colloquially, "move [=change address]". E.g., "When did GKB QSY from Northolt to Portishead....?"[10]

QTH - "My location is…"; colloquially in voice or writing, "location". E.g., "The OCF [antenna] is an interesting build but at my QTH a disappointing performer."[11]


The majority of the Q codes have slipped out of common use; for example today reports such as QAU ("I am about to jettison fuel") and QAZ ("I am flying in a storm") would be voice or computerized transmissions. But several remain part of the standard ICAO radiotelephony phraseology in aviation.

Altimeter Settings

Code Meaning Sample use
QFE Atmospheric pressure at a specified datum such as airfield runway threshold. When set, the altimeter reads the height above the specified datum. Runway in use 22 Left, QFE 990 millibars
QFF Atmospheric pressure at a place, reduced to MSL using the actual temperature at the time of observation as the mean temperature.
QNE Atmospheric pressure at sea level in the International Standard Atmosphere (ISA), equal to 1013.25 mbar or hPa and used as reference for measuring the pressure altitude. When Flight Levels are used as an indication of altitude, 1013.25 hPa is used as mean sea level (QNH).
QNH Atmospheric pressure at mean sea level (may be either a local, measured pressure or a regional forecast pressure (RPS)). When set on the altimeter it reads altitude. Request Leeds QNH

Radio Navigation

Code Meaning Sample use
QDM Magnetic heading to a station (callsign) request QDM (callsign) [12]
QDL Series of bearings taken at regular intervals
QDR Magnetic bearing from a station (callsign) request QDR (callsign) [12]
QFU Magnetic bearing of the runway in use Runway 22 in use, QFU 220[13]
QGE Distance
QGH Controlled Descent through Clouds (Royal Air Force use)
QTE True bearing from a station True bearing, True bearing, (callsign) request QTE (callsign) [12]
QTF Position in relation to a point of reference or in latitude and longitude
QUJ True heading to a station

Radio Procedures

Code Meaning Sample use
QGH controller-interpreted DF let-down procedure, on UHF or VHF[14]


Q signals are no longer used in the maritime service, as Morse code is now very rarely used.

See also[edit]


  1. ^ National Communications Magazine. Radio codes & signals - Florida. Retrieved 2010-01-30.
  2. ^ The Q Code
  3. ^ ICAO PANS (Procedures for Air Navigation Services) Doc 8400: The ICAO Q Code.
  4. ^ http://www.globalsecurity.org/military/library/policy/navy/nrtc/14244_ch4.pdf
  5. ^ www.portland-amateur-radio-club.org.uk - Web site hosted by Freeola.com
  6. ^ http://kyalami.homeip.net/qcodes.htm
  7. ^ ACP 131(E), Communications Instructions - Operating Signals, March 1997. Chapter 2 contains a full list of 'Q' codes
  8. ^ "International Morse code Recommendation ITU-R M.1677-1". itu.int. International Telecommunication Union. October 2009. Retrieved 23 December 2011. 
  9. ^ "COMMUNICATIONS INSTRUCTIONS OPERATING SIGNALS". Combined Communications-Electronics Board. April 2006. Retrieved 2013-{{subst:LOCALMONTH}}-{{subst:LOCALDAY2}}. 
  10. ^ Post in the uk.radio.amateur newsgroup Dated 2010-08-21. Accessed 2013-08-04.
  11. ^ Has anyone used a tuner with an Off Centre Fed Dipole? How well did it work? Article on Amateur Radio Wiki. Accessed 2013-08-04.
  12. ^ a b c http://www.caa.co.uk/docs/33/CAP413.PDF
  13. ^ QFU on The Free Dictionary
  14. ^ QGH on The Free Dictionary

External links[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Q_code — Please support Wikipedia.
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