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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.
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, and QRA-QUZ for all services.
The following table reviews a sample of the all-services Q codes adopted by the 1912 Convention:
| 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. |
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.
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.
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 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 Continuous Wave (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.
The following table gives the most common Q codes used in amateur radio:
| 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 5 |
| 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 (Morse abbreviation: TNX QSO 73 SK) |
| 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") 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."
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
Q kód | Q-Code | Código Q de señales | Code Q | Q-code | Q符号 | Kod Q | Código Q | Q-коды | Q-koodi | Q简语
"Q code"