Ten-codes, officially known as ten signals, are brevity codes used to represent common phrases in voice communication, particularly by law enforcement and in citizens band (CB) radio transmissions. The police version of ten-codes is officially known as the APCO Project 14 Aural Brevity Code. [1]
The codes, developed during 1937–1940 and expanded in 1974 by the Association of Public-Safety Communications Officials-International (APCO), allow brevity and standardization of message traffic. They have historically been widely used by law enforcement officers in North America, but in 2006, due to the lack of standardization, the U.S. federal government recommended they be discontinued in favor of everyday language. [2]
APCO first proposed Morse code brevity codes in the June 1935 issue of The APCO Bulletin, which were adapted from the procedure symbols of the U.S. Navy, though these procedures were for communications in Morse code, not voice. [3]
In August 1935, the APCO Bulletin published a recommendation that the organization issue a handbook that described standard operating procedures, including: [4]
The development of the APCO Ten Signals began in 1937 [5] to reduce use of speech on the radio at a time when police radio channels were limited. Credit for inventing the codes goes to Charles "Charlie" Hopper, communications director for the Illinois State Police, District 10 in Pesotum, Illinois. Hopper had been involved in radio for years and realized there was a need to abbreviate transmissions on State Police bands. [6] Experienced radio operators knew the first syllable of a transmission was frequently not understood because of quirks in early electronics technology. Radios in the 1930s were based on vacuum tubes powered by a small motor-generator called a dynamotor. The dynamotor took from 1/10 to 1/4 of a second to "spin up" to full power. Police officers were trained to push the microphone button, then pause briefly before speaking; however, sometimes they would forget to wait. Preceding each code with "ten-" gave the radio transmitter time to reach full power. An APCO Bulletin of January 1940 lists codes assigned as part of standardisation. [7]
In 1954, APCO published an article describing a proposed simplification of the code, based on an analysis conducted by the San Diego Police Department. [8] In the September 1955 issue of the APCO Bulletin, a revision of the Ten-Signals was proposed, [9] and it was later adopted.
The Ten Signals were included in APCO Project Two (1967), "Public Safety Standard Operating Procedures Manual", published as study cards in APCO Project 4 (1973), "Ten Signal Cards", and then revised in APCO Project 14 (1974). [10] [11] [12] [13]
Ten-codes, especially "10-4" (meaning "understood") first reached public recognition in the mid- to late-1950s through the popular television series Highway Patrol , with Broderick Crawford.[ citation needed ] Crawford would reach into his patrol car to use the microphone to answer a call and precede his response with "10-4".
Ten-codes were adapted for use by CB radio enthusiasts. C. W. McCall's hit song "Convoy" (1975), depicting conversation among CB-communicating truckers, put phrases like "10-4" and "what's your twenty?" (10-20 for "where are you?") into common use in American English.[ citation needed ]
The movie Convoy (1978), loosely based on McCall's song, further entrenched ten-codes in casual conversation, as does the movie Smokey and the Bandit.
The ten-codes used by the New York Police Department [14] have returned to public attention thanks to the popularity of the television series Blue Bloods . However, the ten-codes used by the NYPD are not the same as those used in the APCO system. For example, in the NYPD system, Code 10-13 means "Officer needs help," whereas in the APCO system "Officer needs help" is Code 10-33.
The New Zealand reality television show Ten 7 Aotearoa (formerly Police Ten 7) takes its name from the New Zealand Police ten-code 10-7, which means "Unit has arrived at job".[ citation needed ]
The syndicated internet radio countdown program "What's your Twenty" [15] is named after the code for location.
The Chicago Police Department uses the radio code '10-1', which means an officer needs urgent help right away. The Chicago P.D. (TV series) TV show also uses '10-1' as well. [16]
Often when an officer retires, a call to dispatch is made. The officer gives a 10-7 code (Out of service) and then a 10-42 code (ending tour of duty). [17] [18]
Signal | APCO Meaning | ||||||||
---|---|---|---|---|---|---|---|---|---|
1937 APCO | 1939 First Published Set (17 signals) [19] | 1940 (APCO Standards Committee) [20] [21] | 1955 (National Operating Procedure Committee) [22] | APCO Project 2 (1967) [23] | APCO Project 4 (1973) | APCO Project 14 (1974) [24] [25] | Clear Speech (c. 1971) (plain language to replace Ten Codes) [26] | Phrase Word Brevity Code (c. 1979) [27] | |
Procedure and Officer Details | |||||||||
10-MAX | AWOL | - | - | - | Corrupt Officer | Officer not following orders | Insubordination/Rogue Officer | ||
Go Ahead | |||||||||
Under Control | |||||||||
In Pursuit | |||||||||
Traffic Stop | |||||||||
10-0 | — | — | — | — | Use caution | ||||
10-1 | Receiving poorly. | Unable to copy - change location | Signal Weak | Unable to copy - change location | Unreadable | ||||
10-2 | Receiving well. | Signals good | Signal Good | — | |||||
10-3 | Stop transmitting. | Disregard last information | Stop transmitting | Stop Transmitting | |||||
10-4 | Acknowledgement. | Message received | Acknowledgement | Affirmative (Ok) | Roger | Roger/Affirmative | |||
10-5 | Relay. | Relay (To) | Relay | ||||||
10-6 | Busy. | Busy, stand by | Busy -Stand by unless urgent | Busy | Busy | ||||
10-7 | Out of service. | Out of service (Give location and/or telephone number) | Out of Service | Out at ... | Out of Service | ||||
10-7 A | — | Not Available | |||||||
10-7 B | Off Radio | ||||||||
10-8 | In service. | In Service | Clear | In Service | |||||
10-9 | Repeat, conditions bad. | Repeat | Say Again | ||||||
10-10 | Out of service—subject to call. | On minor detail, subject to call | Fight in progress | Negative | — | ||||
10-11 | Dispatching too rapidly. | Stay in service | Dog Case | ... On Duty | On Radio | ||||
10-12 | Officials or visitors present. | Visitors or officials present | Stand by (stop) | Stand By (Stop) | Stand by | Stand By | |||
10-13 | Advise weather and road conditions. | Weather and road conditions | Weather and road report | Existing Conditions | Weather report/road report | ||||
10-14 | Convoy or escort. | Convoy or escort | Report of prowler | Message/Information | — | Prepare to Copy | |||
10-15 | We have prisoner in custody. | Civil disturbance | Message Delivered | Disturbance | |||||
10-16 | Pick up prisoner at ... | Domestic trouble | Reply to Message | — | |||||
10-17 | Pick up papers at ... | Meet complainant | Enroute | Responding | |||||
10-17 A | — | — | — | — | Theft | ||||
10-17 B | Vandalism | ||||||||
10-17 C | Shoplifting | ||||||||
10-18 | Complete present assignment as quickly as possible. | Anything for us? | Complete assignment quickly | Urgent | Priority | ||||
10-19 | Return to your station. | Nothing for you | Return to ... | (In) Contact | Return to ... | ||||
10-20 | What is your location? | Location | Location | Location | Location | ||||
10-21 | Call this station by telephone. | Call ... by phone | Call (...) by Phone | Call ... | Telephone | ||||
10-22 | Take no further action last information. | Report in person to ... | Disregard | Disregard | |||||
10-23 | Stand by until no interference. | Arrived at scene | Arrived at Scene | On scene | |||||
10-24 | Trouble at station—unwelcome visitors—all units vicinity report at once. | Finished with last assignment | Assignment completed | Assignment Completed | — | Available | |||
10-25 | Do you have contact with...? | Operator or officer on duty? | Report in person to (meet) ... | Report to (Meet) ... | Meet ... or contact ... | ||||
10-26 | Can you obtain automobile registration information? | Holding subject, rush reply | Detaining subject, expedite | Estimated Arrival Time | Detaining subject, expedite | ||||
10-27 | Any answer our number...? | Request driver's license information | Drivers license information | License/Permit Information | Drivers license information on ... | ||||
10-28 | Check full registration information. | Request full registration information | Vehicle registration information | Ownership Information | Registration information on ... | ||||
10-29 | Check for wanted. | Check record for wanted | Check records for wanted. | Records Check | Check for wanted on ... | ||||
Emergency or Unusual | |||||||||
10-30 | Does not conform to rules and regulations. | Illegal use of radio | Danger/Caution | — | Use Caution | ||||
10-31 | Is lie detector available? | Emergency basis, all squads, 10-11 | Crime in progress | Pick Up | — | ||||
10-31 A | — | — | — | — | Burglary | ||||
10-31 B | Robbery | ||||||||
10-31 C | Homicide | ||||||||
10-31 D | Kidnapping | ||||||||
10-31 E | Shooting | ||||||||
10-32 | Is drunkometer available? | Chase, all squads stand by | Man with gun | ... Units Needed (Specify) | — | ||||
10-33 | Emergency traffic at this station—clear? | Emergency traffic this station | EMERGENCY | Help Me Quick | Help Officer | ||||
10-34 | Clear for local dispatch? | Trouble at station, assistance needed | Riot | Time | |||||
10-35 | Confidential information. | Major crime, blockade | Major crime alert | —Reserved— | |||||
10-36 | Correct time? | — | Correct time | ||||||
10-37 | Operator on duty? | No rush | Investigate suspicious vehicle | ||||||
10-38 | Station report—satisfactory. | Hurry, but do not use red light or siren | Stopping suspicious vehicle (Give station complete description before stopping). | Traffic stop on ... | |||||
10-39 | Your Nr...delivered to addressee. | Use red light and siren | Urgent-Use light and siren | — | |||||
General Use | Private Use | ||||||||
10-40 | Advise if Officer...available for radio call. | Notification | Silent run - No light or siren | — | |||||
10-41 | Tune to ... kcs. for test with mobile unit or emergency service. | Car change at ... | Beginning tour of duty | ||||||
10-42 | — | Crew change at ... | Ending tour of duty | Off duty | |||||
10-43 | Take school crossing | Information | — | ||||||
10-44 | — | Request permission to leave patrol ... for ... | Request for ... | ||||||
10-45 | Animal carcass in ... lane at ... | — | |||||||
10-46 | Assist motorist | Assist motorist | |||||||
10-47 | Emergency road repairs needed | — | |||||||
10-48 | Traffic standard needs repairs | ||||||||
10-49 | Hourly report mark | Traffic light out | East bound green light out (etc.) | ||||||
Accident and Vehicle Handling | |||||||||
10-50 | — | Auto accident, property damage only | Accident—F, PI, PD | Traffic (F, PD) Traffic
| |||||
10-51 | Auto accident, wrecker sent | Wrecker needed | — | ||||||
10-52 | Auto accident, personal injuries, ambulance sent | Ambulance needed | |||||||
10-53 | Auto accident, fatal | Road blocked | |||||||
10-54 | — | Livestock on highway | |||||||
10-55 | Drunken driver | Intoxicated driver | |||||||
10-56 | — | Intoxicated pedestrian | Drunk pedestrian | ||||||
10-57 | — | Hit and run—F, PI, PD | — | ||||||
10-58 | Is wrecker on the way? | Direct traffic | |||||||
10-59 | Is ambulance on the way? | Convoy or escort | |||||||
Net Message Handling | |||||||||
10-60 | What is next item (message) number? | What is your next message number? | Squad in vicinity | — | |||||
10-61 | Stand by for CW traffic on ... kcs. | CW traffic | Personnel in area. | ||||||
10-62 | Unable to copy phone—use CW. | Any answer our Nr. ... | Reply to message | ||||||
10-63 | Net directed. | Time | Prepare to make written copy | Prepare to copy | |||||
10-64 | Net free. | — | Message for local delivery | — | |||||
10-65 | Clear for item (message) assignment? | Clear for message assignment | Net message assignment | ||||||
10-66 | Clear for cancellation? | Clear for cancellation | Message cancellation | ||||||
10-67 | Stations...carry this item (message). | Clear for net message | Clear to read net message | ||||||
10-68 | Repeat dispatch. | — | Dispatch information | ||||||
10-69 | Have you dispatched...? | Message received | |||||||
Fire | |||||||||
10-70 | Net message (State net traffic). | Fire, phone alarm | Fire alarm | Fire | |||||
10-71 | Proceed with traffic in sequence (busy here). | Box alarm | Advise nature of fire (size, type, and contents of building) | — | |||||
10-72 | — | Second alarm | Report progress on fire | ||||||
10-73 | Third alarm | Smoke report | |||||||
10-74 | Fourth alarm | Negative | Negative | ||||||
10-75 | Fifth alarm | In contact with | — | ||||||
10-76 | Fire equipment needed | En Route | En route ... | ||||||
10-77 | Fire, grass | ETA (Estimated Time of Arrival) | ETA (Estimated time of arrival) | ||||||
10-78 | Set up command post | Need assistance | Request Assistance | ||||||
10-79 | Report progress on fire | Notify coroner | Notify coroner (to be done by phone whenever possible) | ||||||
The 80 series is reserved for assignment by nets for local use. | Personal Favors | — | |||||||
10-80 | ... tower lights at this station burned out. | — | — | Chase | |||||
10-81 | Officer Nr. ... will be at your station ... | — | |||||||
10-82 | Reserve room with bath at hotel for officer Nr. ... | Reserve hotel room | Reserve lodging | ||||||
10-83 | Have officer Nr. ... call this station by telephone. | — | — | ||||||
10-84 | Advise telephone Nr. ... your city that officer Nr. ... will not return this date. | If meeting ... advise ETA | |||||||
10-85 | Officer ... left this station for ... (Jefferson City) (Des Moines) at ... | Will be late | |||||||
10-86 | Officer ... left this station for ... at ... | — | |||||||
10-87 | Officer Nr. ... will be in ... if officer Nr. ... will be in. | Meet the officer at ______. | |||||||
10-88 | What phone number shall we call to make station to station call to officer Nr. ...? | Advise phone number for station to station call | Advise present telephone number of ... | ||||||
10-89 | Request radio service man be sent to this station... | Radio transmission | — | Bomb threat | |||||
Technical | |||||||||
10-90 | Radio service man will be at your station .... | Transmit on alternate frequency | Bank alarm | Alarm (type of alarm) | |||||
10-91 | Prepare for inspection (date) ... (time) ... | — | Unnecessary use of radio | Pick up prisoner | |||||
10-92 | Your quality poor—transmitter apparently out of adjustment. | — | Parking complaint | ||||||
10-93 | Frequencies to be checked this date. | Frequency check | Blockade | — | |||||
10-94 | Test—no modulation—for frequency check. | Give me a test | Drag racing | ||||||
10-95 | Test intermittently with normal modulation for ... | — | — | Prisoner in custody | |||||
10-96 | Test continuously with tone modulation for ... | Mental subject | — | ||||||
10-97 | — | — | Check traffic signal | ||||||
10-98 | Prison or jail break | Prison/jail break | |||||||
10-99 | Records indicate wanted or stolen | Wanted/stolen |
While ten-codes were intended to be a terse, concise, and standardized system, the proliferation of different meanings can render them useless in situations when officers from different agencies and jurisdictions need to communicate.
In the fall of 2005, responding to inter-organizational communication problems during the rescue operations after Hurricane Katrina, the United States Federal Emergency Management Agency (FEMA) discouraged the use of ten-codes and other codes due to their wide variation in meaning. [28] [29] The Department of Homeland Security's SAFECOM program, established in response to communication problems experienced during the September 11 attacks also advises local agencies on how and why to transition to plain language, [30] and their use is expressly forbidden in the nationally standardized Incident Command System, as is the use of other codes. [31]
APCO International stated in 2012 that plain speech communications over public safety radio systems is preferred over the traditional 10-Codes and dispatch signals. [32] Nineteen states had changed to plain English by the end of 2009. [33] As of 2011 [update] , ten-codes remained in common use in many areas, but were increasingly being phased out in favor of plain language. [2]
In 1971, the Public Safety Department of Lakewood, Colorado, published a study comparing the APCO Ten-code with the proposed Clear Speech procedure. The study used standards for judgment of both communications procedures based on The Public Safety Communications Standard Operating Procedure Manual, 1970 edition, published by APCO. Accordong to the report, the Clear Speech Procedure was to replace ten-codes in all Public Safety Department radio communication since January 28, 1972. [26]
Was (Ten-Code) | Now (Procedure Word) |
---|---|
10-0 | Use Caution |
10-1 | Unable to copy – change location |
10-3 | Stop transmitting |
10-4 | Roger |
10-5 | Relay |
10-6 | Busy |
10-7 | Out at... |
10-8 | Clear |
10-9 | Say again |
10-12 | Stand by |
10-13 | Weather report/road report |
10-15 | Disturbance |
10-17A | Theft |
10-17B | Vandalism |
10-17C | Shoplifting |
10-18 | Urgent |
10-19 | Return to... |
10-20 | Location |
10-21 | Call... |
10-22 | Disregard |
10-23 | On scene |
10-25 | Meet...or contact... |
10-26 | Detaining subject, expedite |
10-27 | Drivers License information on... |
10-28 | Registration information on... |
10-29 | Check for wanted on... |
10-31A | Burglary |
10-31B | Robbery |
10-31C | Homicide |
10-31D | Kidnapping |
10-31E | Shooting |
10-38 | Traffic stop on... |
10-42 | Off duty |
10-44 | Request for... |
10-46 | Assist motorist |
10-49 | East bound green light out (etc.) |
10-50 | Traffic
|
10-56 | Drunk pedestrian |
10-63 | Prepare to copy |
10-70 | Fire |
10-74 | Negative |
10-76 | En route... |
10-77 | ETA (Estimated time of arrival) |
10-78 | Request assistance |
10-79 | Notify coroner (to be done by phone whenever possible) |
10-80 | Chase |
10-89 | Bomb threat |
10-90 | Alarm (type of alarm) |
10-91 | Pick up prisoner |
10-92 | Parking complaint |
10-95 | Prisoner in custody |
10-97 | Check traffic signal |
10-98 | Prison/jail break |
10-99 | Wanted/stolen |
|
Code | Meaning |
---|---|
CODE ZERO | Echo response |
CODE ONE | Informs all units to STANDBY – STOP TRANSMITTING. Do not transmit, except for emergency messages, while Code 1 is in effect. Dispatch shall announce, "Clear Code 1," when the condition is secured. |
CODE TWO | Indicates an "urgent" call short of an "emergency" situation. A Code 2 call has priority over all other police activities except "emergencies". Proceed directly to Code 2 calls as quickly as is consistent with safety. Agents may, in exceptional cases, use their emergency equipment (both visual and audible to comply with state law) to traverse an otherwise clear intersection against a red traffic control device. Once clear of the intersection – turn off the emergency equipment. |
CODE THREE | Indicates an EMERGENCY call. Red lights and siren are authorized. Proceed as quickly as possible with due regard for safety, and in compliance with the laws governing emergency vehicles. |
CODE FOUR | Used to indicate that sufficient units have responded to a location, or that assistance is not needed, or is no longer needed. |
CODE FIVE | Used when Wanted/Records checks are requested by an agent to alert the agent of a wanted felon, a person known to be dangerous or a person known to be mentally unstable. A backup unit shall be dispatched Code 2 on all Code 5's. Personnel will NOT proceed with Code 5 details until the receiving unit requests some. The unit receiving a Code 5 will request the details when he is in a safe position to do so, which might not be until his backup arrives. |
CODE SIX | When an agent is dispatched to a traffic accident, and the dispatcher states, "Code 6," the agent will advise the drivers involved to proceed to the station to file their reports. This will only be done if there are no injuries, no unusual circumstance and the vehicles are safely operable. Driver Exchange Forms will be completed at the scene to include the C. R. number. |
CODE SEVEN | Indicates "out of service – personal." |
CODE EIGHT | Assist a fire department. |
About 1979, APCO created the Phrase Word Brevity Code as a direct replacement for the Ten-code. [27]
Phrase Word | English Meaning | APCO TEN CODE |
---|---|---|
Use Caution | Caution: dangerous condition is suspected to exist. | 10-0 |
Unreadable | Radio signal is too weak to receive. | 10-1 |
Out of Service | Unit, vehicle or person is not working | 10-7 |
In Service | Unit, vehicle or person is working but not necessarily "available" or "on radio." | 10-8 |
Available | Unit is in service ready to accept assignment, not necessarily by radio. | 10-24 |
Not Available | Unit cannot accept another assignment, but may be "on radio." | 10-7A |
Prepare to Copy | Dispatcher is about to give lengthy message. | 10-14 |
Go | You have been given clearance to transmit your message. | - - |
Roger (Received) | Message received and understood. | 10-4 |
Say Again (Repeat) | Repeat your message. | 10-9 |
Stand By | Stop transmitting and wait for further instructions. | 10-12 |
Disregard (Recall) | Cancel your present assignment. | 10-22 |
Off Radio | Unit is not capable of being contacted by radio, but may be "available." | 10-7B |
On Radio | Unit is capable of being contacted by radio, but not necessarily "available." | 10-11 |
Responding | Unit is en route to assigned location. | 10-17 |
Under Control | Situation is under control when no further assistance is anticipated. | - - |
Telephone (Tel. # or person) | Call by telephone specified number or person. | 10-21 |
Priority | When transmitted, means that the following transmission must have immediate attention. | - - |
In Pursuit | Unit is chasing a vehicle and requires assistance from other units. | - - |
Traffic Stop | Unit is going to stop a motorist. | - - |
Help Officer | Help me quick (emergency). | 10-33 |
Affirmative | Yes. | 10-4 |
In 1980, the National Incident Management System published a document, ICS Clear Text Guide, which was another attempt to create a replacement for Ten-codes. The list of code words was republished in the 1990 Montana Mutual Aid and Common Frequencies document. [34]
Procedure Word | Meaning |
---|---|
Unreadable | Used when signal received is not clear. In most cases, try to add the specific trouble. Example: "Unreadable, background noise." |
Loud and Clear | Self-explanatory |
Stop Transmitting | |
Copy, Copies | Used to acknowledge message received. Unit radio identifier must also be used. Example: "Engine 2675, copies." |
Affirmative | Yes |
Negative | No |
Respond, Responding | Used during dispatch – proceed to or proceeding to an incident. Example: "Engine 5176, respond ..." or "St. Helena, Engine 1375 responding." |
Enroute | Normally used by administrative or staff personnel to designate destinations. Enroute is NOT a substitute for responding. Example: "Redding, Chief 2400 enroute RO II." |
In-quarters, with Station Name or Number | Used to indicate that a units is in a station. Example: "Morgan Hill, Engine 4577 in-quarters, Sunol." |
Uncovered | Indicates a unit is not in-service, because there are no personnel to operate it. |
Out-Of-Service | Indicates a unit is mechanically out of service. Example: "Aburn, transport 2341, out-of-service." Note, when repairs have been completed the following phrase should be used: "Aburn transport 2341, back in-service, available." |
In-Service | This means that the unit is operating, not in response to a dispatch. Example: "Fortuna, Engine 1283, in-service, fire prevention inspections." |
Repeat | Self-explanatory |
Weather | |
Return to | Normally used by communications center to direct units that are available to a station or other location. |
What is your Location? | Self-explanatory |
Call ____ by Phone | |
Disregard Last Message | |
Stand-By | |
Vehicle Registration Check | |
Is ____ Available for a Phone Call? | |
At Scene | Used when Units arrive at the scene of an incident. Example: "Perris, Engine 6183, at scene." |
Available at Residence | Used by administrative or staff personnel to indicate they are available and on-call at their residence. |
Can Handle | Used with the amount of equipment needed to handle the incident. Example: "Susanville Battalion 2212, can handle with units not at scene." |
Burning Operations | Self-explanatory |
Report on Conditions | |
Fire under Control | |
Emergency Traffic Only | Radio users will confine all radio transmissions to an emergency in progress or a new incident. Radio traffic which includes status information such as responding, reports on conditions, at scene and available will not be authorized during this period. |
Emergency Traffic | Term used to gain control of radio frequency to report an emergency. All other radio users will refrain from using that frequency until cleared for use by the communications center. |
Resume Normal Traffic | Self-explanatory |
Brevity codes other than the APCO 10-code are frequently used, and include several types:
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy.
In communication, a code word is an element of a standardized code or protocol. Each code word is assembled in accordance with the specific rules of the code and assigned a unique meaning. Code words are typically used for reasons of reliability, clarity, brevity, or secrecy.
The (International) Radiotelephony Spelling Alphabet, commonly known as the NATO phonetic alphabet, is the most widely used set of clear code words for communicating the letters of the Roman alphabet. Technically a radiotelephonic spelling alphabet, it goes by various names, including NATO spelling alphabet, ICAO phonetic alphabet and ICAO spelling alphabet. The ITU phonetic alphabet and figure code is a rarely used variant that differs in the code words for digits.
The Q-code is a standardised collection of three-letter codes that each start with the letter "Q". It is an operating signal initially developed for commercial radiotelegraph communication and later adopted by other radio services, especially amateur radio. To distinguish the use of a Q-code transmitted as a question from the same Q-code transmitted as a statement, operators either prefixed it with the military network question marker "INT" or suffixed it with the standard Morse question mark UD.
Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications.
SOS is a Morse code distress signal, used internationally, originally established for maritime use. In formal notation SOS is written with an overscore line, to indicate that the Morse code equivalents for the individual letters of "SOS" are transmitted as an unbroken sequence of three dots / three dashes / three dots, with no spaces between the letters. In International Morse Code three dots form the letter "S" and three dashes make the letter "O", so "S O S" became a common way to remember the order of the dots and dashes. IWB, VZE, 3B, and V7 form equivalent sequences, but traditionally SOS is the easiest to remember.
A radiotelephone, abbreviated RT, is a radio communication system for conducting a conversation; radiotelephony means telephony by radio. It is in contrast to radiotelegraphy, which is radio transmission of telegrams (messages), or television, transmission of moving pictures and sound. The term is related to radio broadcasting, which transmit audio one way to listeners. Radiotelephony refers specifically to two-way radio systems for bidirectional person-to-person voice communication between separated users, such as CB radio or marine radio. In spite of the name, radiotelephony systems are not necessarily connected to or have anything to do with the telephone network, and in some radio services, including GMRS, interconnection is prohibited.
The APCO phonetic alphabet, a.k.a. LAPD radio alphabet, is the term for an old competing spelling alphabet to the ICAO radiotelephony alphabet, defined by the Association of Public-Safety Communications Officials-International from 1941 to 1974, that is used by the Los Angeles Police Department (LAPD) and other local and state law enforcement agencies across the state of California and elsewhere in the United States. It is the "over the air" communication used for properly understanding a broadcast of letters in the form of easily understood words. Despite often being called a "phonetic alphabet", it is not a phonetic alphabet for transcribing phonetics.
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Radiotelephony procedure includes various techniques used to clarify, simplify and standardize spoken communications over two-way radios, in use by the armed forces, in civil aviation, police and fire dispatching systems, citizens' band radio (CB), and amateur radio.
Project 25 is a suite of standards for interoperable digital two-way radio products. P25 was developed by public safety professionals in North America and has gained acceptance for public safety, security, public service, and commercial applications worldwide. P25 radios are a direct replacement for analog UHF radios, but add the ability to transfer data as well as voice, allowing for more natural implementations of encryption and text messaging. P25 radios are commonly implemented by dispatch organizations, such as police, fire, ambulance and emergency rescue service, using vehicle-mounted radios combined with repeaters and handheld walkie-talkie use.
A Radio code is any code that is commonly used over a telecommunication system such as Morse code, brevity codes and procedure words.
A police code is a brevity code, usually numerical or alphanumerical, used to transmit information between law enforcement over police radio systems in the United States. Examples of police codes include "10 codes", signals, incident codes, response codes, or other status codes. These code types may be used in the same sentence to describe specific aspects of a situation.
Procedural signs or prosigns are shorthand signals used in Morse code telegraphy, for the purpose of simplifying and standardizing procedural protocols for land-line and radio communication. The procedural signs are distinct from conventional Morse code abbreviations, which consist mainly of brevity codes that convey messages to other parties with greater speed and accuracy. However, some codes are used both as prosigns and as single letters or punctuation marks, and for those, the distinction between a prosign and abbreviation is ambiguous, even in context.
In telecommunications, APCO-16, is a US standard for the characteristics and capabilities of public safety trunked radio systems.
A spelling alphabet is a set of words used to represent the letters of an alphabet in oral communication, especially over a two-way radio or telephone. The words chosen to represent the letters sound sufficiently different from each other to clearly differentiate them. This avoids any confusion that could easily otherwise result from the names of letters that sound similar, except for some small difference easily missed or easily degraded by the imperfect sound quality of the apparatus. For example, in the Latin alphabet, the letters B, P, and D sound similar and could easily be confused, but the words "bravo", "papa" and "delta" sound completely different, making confusion unlikely.
A radiogram is a formal written message transmitted by radio. Also known as a radio telegram or radio telegraphic message, radiograms use a standardized message format, form and radiotelephone and/or radiotelegraph transmission procedures. These procedures typically provide a means of transmitting the content of the messages without including the names of the various headers and message sections, so as to minimize the time needed to transmit messages over limited and/or congested radio channels. Various formats have been used historically by maritime radio services, military organizations, and Amateur Radio organizations.
Procedure words are words or phrases limited to radio telephone procedure used to facilitate communication by conveying information in a condensed standard verbal format. Prowords are voice versions of the much older procedural signs for Morse code which were first developed in the 1860s for Morse telegraphy, and their meaning is identical.
Association of Public-Safety Communications Officials (APCO) International was founded in 1935. It is the world’s oldest and largest organization of public safety communications professionals and supports the largest U.S. membership base of any public safety association. APCO’s mission is to be a leader in providing public safety communications expertise, professional development, technical assistance, advocacy and outreach to benefit its members and the public.
Brevity codes are used in amateur radio, maritime, aviation and military communications. The codes are designed to convey complex information with a few words or codes. Some terms are classified to the public.
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