ACP-131
Encyclopedia
ACP-131 is the controlling publication for the listing of Q code
s and Z code
s. It is published by NATO Allied countries, and revised from time to time. When the meanings of the codes contained in ACP-131 are translated into various languages, the codes provide a means of communicating between ships of various nations, such as during a NATO exercise, when a common language
is not in effect.
telegraphy
for use by radio operators using Morse Code
on continuous wave
(CW) telegraphy. It became especially useful, and even essential, to wireless
radio operators on both military and civilian ships at sea before the development of advanced single-sideband telephony
in the 1960s.
s as communication paths and relays, was always subject to unpredictable fade outs caused by weather
conditions, amount of emission power in kilowatts at the transmitter
, radio frequency
of the transmission, type of emission, type of transmitting antenna
, signal basewave shape and size, sensitivity of the receiver
and presence, or lack of presence, of atmospheric reflective layers above the earth, such as the E-layer and F-layers, the type of receiving antenna, the time of day, and numerous other factors.
Because of these factors which often resulted in limiting periods of transmission time on certain frequencies to only several hours a day, or only several minutes, it was found necessary to keep each wireless transmission as short as possible and to still get the message through. This was particularly true of CW radio circuits shared by a number of operators, with some waiting their turn to transmit.
As a result, an operator communicating by CW radio to another operator, wanting to know how the other operator was receiving the signal, could send out a message on his key in Morse Code
stating, “How are you receiving me?”
..../---/.-- .-/.-./. -.--/---/..- .-././-.-././../...-/../-./--. --/. ..--..
Using ACP-131 codes, the question could be phrased simply “INT QRK”
..-.- --.-/.-./-.-
resulting in much more efficient use of circuit time.
If the receiver hears the sender in a “loud and clear” condition, the response would be "QRK5":
--.-/.-./-.- .....
All of which requires less circuit time and less “pounding” on the key by the sending operators.
Should the receiving operator not understand the sending operator, the receiving operator would send “IMI”
..--..
The other operator would respond again with:
..-.- --.-/.-./-.-
which is much easier than retransmitting “How are you receiving me?”
Typical Simplex
military voice exchange:
Q. Lima Five this is Charlie Two – Radio Check Over.
A. Lima Five - ok over.
A. Charlie Two - ok out.
However, some voice operators, such as amateur radio operators, find it convenient or traditional to use some of the Q codes, such as QSL, QRK, etc.
Q code
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...
s and Z code
Z code
Z Code is a set of codes used in CW, TTY and RTTY radio communication. Actually, there are different sets of Z-codes: one originally developed by Cable & Wireless Ltd., for commercial communications in the early days of wire and radio communications, another one independently developed by NATO...
s. It is published by NATO Allied countries, and revised from time to time. When the meanings of the codes contained in ACP-131 are translated into various languages, the codes provide a means of communicating between ships of various nations, such as during a NATO exercise, when a common language
Language
Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication...
is not in effect.
History
The original edition of ACP-131 was published by the U.S. military during the early years of radioRadio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
telegraphy
Telegraphy
Telegraphy is the long-distance transmission of messages via some form of signalling technology. Telegraphy requires messages to be converted to a code which is known to both sender and receiver...
for use by radio operators using Morse Code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
on continuous wave
Continuous wave
A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...
(CW) telegraphy. It became especially useful, and even essential, to wireless
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...
radio operators on both military and civilian ships at sea before the development of advanced single-sideband telephony
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
in the 1960s.
Reason for the codes
Radio communications, prior to the advent of landlines and satelliteSatellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
s as communication paths and relays, was always subject to unpredictable fade outs caused by weather
Weather
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
conditions, amount of emission power in kilowatts at the transmitter
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
, radio frequency
Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
of the transmission, type of emission, type of transmitting antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
, signal basewave shape and size, sensitivity of the receiver
Receiver (radio)
A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...
and presence, or lack of presence, of atmospheric reflective layers above the earth, such as the E-layer and F-layers, the type of receiving antenna, the time of day, and numerous other factors.
Because of these factors which often resulted in limiting periods of transmission time on certain frequencies to only several hours a day, or only several minutes, it was found necessary to keep each wireless transmission as short as possible and to still get the message through. This was particularly true of CW radio circuits shared by a number of operators, with some waiting their turn to transmit.
As a result, an operator communicating by CW radio to another operator, wanting to know how the other operator was receiving the signal, could send out a message on his key in Morse Code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
stating, “How are you receiving me?”
..../---/.-- .-/.-./. -.--/---/..- .-././-.-././../...-/../-./--. --/. ..--..
Using ACP-131 codes, the question could be phrased simply “INT QRK”
..-.- --.-/.-./-.-
resulting in much more efficient use of circuit time.
If the receiver hears the sender in a “loud and clear” condition, the response would be "QRK5":
--.-/.-./-.- .....
All of which requires less circuit time and less “pounding” on the key by the sending operators.
Should the receiving operator not understand the sending operator, the receiving operator would send “IMI”
..--..
The other operator would respond again with:
..-.- --.-/.-./-.-
which is much easier than retransmitting “How are you receiving me?”
Applicability of the codes
- Q codes were intended for civilian and military use.
- Z codes were intended for military use.
Applicability of codes by type of emission
- Civilian radio continuous wave (CW): Q codes.
- Military radio continuous wave (CW): Q codes and Z codes.
- Civilian shipboard signal lampSignal lampA signal lamp is a visual signaling device for optical communication . Modern signal lamps are a focused lamp which can produce a pulse of light...
: Q codes. - Military shipboard signal lamp: Q codes and Z codes.
- Military Flag semaphoreFlag semaphoreSemaphore Flags is the system for conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags; it is read when the flag is in a fixed position...
: Q codes and Z codes. - Military teletype: Z codes used as routers in message header.
Voice transmission
The use of Q codes and Z codes was not intended for use on voice circuits, where plain language was speedy and easily recognizable, especially when employing the character recognition system in use at the time, such as ALFA, BRAVO, CHARLIE, etc.Typical Simplex
Simplex communication
Simplex communication refers to communication that occurs in one direction only. Two definitions have arisen over time: a common definition, which is used in ANSI standard and elsewhere, and an ITU-T definition...
military voice exchange:
Q. Lima Five this is Charlie Two – Radio Check Over.
A. Lima Five - ok over.
A. Charlie Two - ok out.
However, some voice operators, such as amateur radio operators, find it convenient or traditional to use some of the Q codes, such as QSL, QRK, etc.
See also
- Q codeQ codeThe 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...
- Z codeZ codeZ Code is a set of codes used in CW, TTY and RTTY radio communication. Actually, there are different sets of Z-codes: one originally developed by Cable & Wireless Ltd., for commercial communications in the early days of wire and radio communications, another one independently developed by NATO...
- Morse codeMorse codeMorse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
- Continuous waveContinuous waveA continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...
- RadioRadioRadio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
- 500 kHz