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A police radio 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 " (such as 10-4 for "okay" or "acknowledged"—sometimes written X4 or X-4), signals, incident codes, response codes , or ...
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.
The first police radio systems were implemented in Detroit in 1928, when the Detroit Police Department set up a one-way radio system to broadcast crime information to police cars. [2] The frequency was assigned the call sign "KOP" by the Federal Communications Commission .
(VFR squawk code for airspace 5,000 feet (1,500 m) and below prior to 15 March 2007 when replaced by the international 7000 code for VFR traffic.) [5] 0022 Germany (VFR squawk code for airspace above 5,000 feet (1,500 m) – prior to 15 March 2007 when replaced by the international 7000 code for VFR traffic.) [5] 0025 Germany
In Germany, before the end of 2008, [12] radio control enthusiasts were able to use frequencies from channel 03 through 67 for radio control of any form of model (air or ground-based), all with odd channel numbers (03, 05, etc. up to ch. 67), [13] with each sanctioned frequency having 50 kHz of bandwidth separation between each adjacent channel.
By the last quarter of 2006 police forces had migrated radio networks from the UHF frequencies to TeTRa on the Airwave network, followed by ambulance services in 2007 and fire services in 2010. [6] Airwave now has a nationwide network of more than 3,000 sites and provides secure voice and data communications to over 300 public safety organisations.
Provides the aircraft's pressure altitude and is usually combined with Mode 3/A to provide a combination of a 4-digit octal code and altitude as Mode 3 A/C, often referred to as Mode A and C [2] 4: Provides a 3-pulse reply, delay is based on the encrypted challenge [1] 5: Provides a cryptographically secured version of Mode S and ADS-B GPS ...
Land mobile radio systems are widely used by the military. Separate bands in the radio spectrum are reserved for their use. This includes portions of the 30-50 MHz band, and the entire 100-100, 100-100.8, and 540-2400 MHz bands, plus shared use of the 170- 170 MHz band.