Q code

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The Q code is a standardized collection of three-letter signals, 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 callsigns have often been limited to restrict ones starting with "Q" or having an embedded three-letter Q sequence.

1 Early Developments
2 Later Usage
3 Amateur Radio
4 See also
5 External links

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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.)

The codes in the range QAA-QNZ are reserved for aeronautical use; QOA-QOZ for maritime use, 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**
Abbre- viation.	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 wave length in meters?	My wave length is ____ meters.
QRJ	How many words have you to send?	I have ____ words to send.
QRK	How do you receive me?	I am receiving well.
QRL	Are you receiving badly? Shall I send 20 `...-.` for adjustment?	I am receiving badly. Send 20 `...-.` for adjustment.
QRM	Are you being interfered with?	I am being interfered with.
QRN	Are the atmospherics strong?	Atmospherics are very strong.

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Later Usage

Over the years, modifications and additions 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.) 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. Used in their formal "question/answer" sense, the meaning varies depending on whether 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 Continuous Wave (CW) traffic networks.

Some Q codes are also used in aviation, in particular QNH and QFE, referring to certain air pressures. 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.

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Amateur Radio

Selected Q codes were soon adopted by amateur radio operators—known informally as "hams". For example, 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, a ham 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.

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

**Q Codes Commonly Used by Radio Amateurs**
Code	Meaning	Sample use
QRI	Tone (T in the RST code)	Your QRI is 9
QRK	Intelligibility (R in the RST code)	Your QRK is 5
QRL	Is this frequency busy?	Used almost exclusively with Morse code, usually before transmitting on a new frequency
QRM	Man-made interference	There's another QSO up 2 kHz that's causing a lot of QRM
QRN	Natural interference, e.g.static crashes	The band is noisy today; There's a lot of QRN
QRO	High- or full-power transmission (usually 100 W or more up to licence limit)	I need to QRO when propagation is poor.
QRP	Low-power transmisssion (usually 5 or 10 W, or less)	I'm using a QRP transmitter here, running only 3 watts
QRS	Send Slower	Please QRS, I'm new to Morse code
QRT	Stop sending	I've enjoyed talking to you, but I have to QRT for dinner now
QRV	I am Ready	Will you be QRV in the upcoming contest?
QRX	Hang on a minute, I'll be right back	Please QRX one
QRZ	Who is calling me?	QRZ? You're very weak. (only someone who has previously called should reply)
QSA	Signal strength	Your QSA is 9
QSB	Fading of signal	There's QSB on your signal
QSD	Your Keying is Defective	You are QSD, check your Transmitter
QSK	Break-in	I can hear you during my transmission, you may QSK
QSL	I Acknowledge receipt	QSL your last transmission. Please QSL via the bureau (i.e. please send me a card confirming this contact).
QSM	Repeat last message	QRM drowned your last message out - please QSM
QSO	A conversation	Thanks very much for the QSO
QSP	Relay	Please QSP this message to my friend
QSX	I am Listening on ... frequency	I QSX 14200 to 14210 kilohertz
QSY	Shift to Transmit on ...	Let's QSY up 5 kilohertz
QTA	Disregard last message	QTA, I didn't mean that
QTH	Location	My QTH is South Park, Colorado
QTR	Exact time	QTR is 2000 Z

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"), QSC ("send cigarettes", not the official meaning of "this is a cargo vessel") and QNB.

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