Ten-codes, officially known as ten signals, are brevity codes used to represent common phrases in voice communication, particularly by US public safety officials and in citizens band (CB) radio transmissions. The police version of ten-codes is officially known as the APCO Project 14 Aural Brevity Code. 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.
History 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. In August 1935, the APCO Bulletin published a recommendation that the organization issue a handbook that described standard operating procedures, including:
A standard message form for use by all police departments. A simple code for service dispatches relating to corrections, repetitions, etc. A standard arrangement of the context of messages, (for example, name and description of missing person might be transmitted as follows: Name, age, height, weight, physical characteristics, clothing; if car used, the license, make, description and motor number. This information would actually be transmitted in the text of the message as follows: John Brown 28-5-9-165 medium build brown eyes dark hair dark suit light hat Mich. 35 lic. W 2605 Ford S 35 blue red wheels 2345678 may go to Indiana). A standard record system for logging the operation of the station. Other important records in accordance with the uniform crime reporting system sponsored by the International Association of Chiefs of Police. The development of the APCO Ten Signals began in 1937 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. 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. In 1954, APCO published an article describing a proposed simplification of the code, based on an analysis conducted by the San Diego Police Department. In the September 1955 issue of the APCO Bulletin, a revision of the Ten-Signals was proposed, 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).
In popular culture Ten-codes, especially "10-4" (meaning "understood") first reached public recognition in the mid- to late-1950s through the television series Highway Patrol, with Broderick Crawford. 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. The movie Convoy (1978), loosely based on McCall's song, further entrenched ten-codes in casual conversation, as did the movie Smokey and the Bandit. 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".
Police officer retirement (North America) 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).
Signals by time period (North America)
Usage by Areas
New Zealand The New Zealand Police use a variety of radio communication codes including its own version of 10-codes seen below.
Philippines
TxtFire Philippines Fire-Specific 10-Codes TxtFire Philippines employs a subset of its standard 10-codes exclusively for fire-response operations. These fire-specific signals are used to dispatch and coordinate firefighting resources on VHF/UHF radio.
Fire-specific code list
Fire response protocols Codes 10-70 through 10-73 automatically trigger dispatch of firefighting units and apparatus. Code 10-45 is used to identify any fire-service vehicle (engine, ladder, tanker, etc.) on the air. All fire-specific traffic takes priority over routine and non-fire messages on the main frequency.
Operational procedures
Emergency protocols Codes 10-70 through 10-73 are designated as fire-specific codes that trigger automatic dispatch protocols within the TxtFire network. Code 10-33 is reserved exclusively for life-threatening emergencies, requiring all non-essential radio traffic to cease immediately.
Communication guidelines Before initiating non-emergency communication with another station, operators must first request permission using code "10-75" from base control and complete the communication within three minutes, or transfer to a secondary channel. During curfew hours (22:00–06:00), only emergency traffic is permitted on the main frequency; routine communications are prohibited. Base control strictly prohibits vulgar language and commercial or personal advertisements on all frequencies.
… excerpt ends here. Continue reading the full article.
