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Police radio is a radio system used by police and other law enforcement agencies to communicate with one another. Police radio systems almost always use two-way radio systems to allow for communications between police officers and dispatchers.
Most modern police radio systems are encrypted, and many jurisdictions have made listening to police radio frequencies as a private citizen illegal.
Before police radio systems were first implemented, police officers assigned to their beat could only communicate with police command using telephone booths, call boxes, police boxes, or physical meetings. Calling for help or signaling other officers could only be done by shouting, using a whistle, or hitting things to make sounds. [1] This meant that properly calling for assistance, reporting an incident or arrest, being dispatched to handle a crime, or requesting police resources was only possible if the officer reached a telephone or call box. [2]
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. To follow FCC regulations, KOP was described as an "entertainment station"; to fulfill this, KOP was made publicly accessible, and music was broadcast between descriptions of stolen vehicles and crime reports. [3] The first two-way police radio system was implemented by the Bayonne, New Jersey police in 1933. [4] [5] The FCC briefly prohibited police radio communications in 1934, but rescinded their decision in 1935. [2]
Due to their cost and size, early police radio systems were only used in police cars and buildings; officers on foot patrol still had to rely on telephones and call boxes. Portable radios introduced in the 1960s made radio communications widely accessible to all officers. Early portable radios were heavy and had short battery life, an issue that gradually disappeared as technology advanced. [2]
Modern police radio systems are often augmented by mobile data terminals to effectively manage units and assignments.
Police radio systems historically used public radio frequencies, and listening to them was, for the most part, legal. Most modern police radio systems switched to encrypted radio systems in the 1990s and 2000s to prevent eavesdroppers from listening in.
In Canada, the Radiocommunication Act states that it is illegal to intercept private radio communications with the intent to divulge or use any information obtained in the interception. This applies to any attempts to listen to emergency services radios and police radios. [6] [7] Additionally, there are prohibitions on certain radio scanner devices. [6] [8]
In Germany, it is illegal for private citizens to listen to police radio, even if it is unintentional. Offenders can be punished with up to two years in prison or a fine.
In Japan, police radio communication regulation is managed by the National Police Agency. Prefectural police manage their own radio communications, which are officially limited to their respective jurisdictions but are capable of being used nationwide if necessary. [9] Individual officers communicate with radio operators in nearby police stations, while police vehicles communicate with their prefectural police's communications command centers, located at prefectural police headquarters. [9]
In Japan, police radio frequencies are encrypted and are illegal for civilians to access.
In Norway, it was historically legal for private citizens to listen to police radio frequencies. However, this is no longer possible, as the Norwegian Police Service switched to "Nødnett", an encrypted radio system.
In the United Kingdom, police radios were pioneered largely by Captain Athelstan Popkess of the Nottingham City Police in the early 1930s, [10] with trials commencing in 1931, and the results published in a 1933–1934 series of articles. [11] These experiments concluded that wireless telegraphy was preferable to wireless telephony, due to better signal reception, less chances of interception, and messages being just as quick to send and receive by Morse-proficient officers.
Popkess paired this use of police radios with his simultaneous development of increased use of police cars for patrol purposes stating that “There can be no real mobility unless [mechanization and communication] are closely related, and each is as efficient as we can make it”. [11]
It is an offence under the Wireless Telegraphy Act 2006 to listen to police radio in the UK. [12] [13] The move from open analogue to the encrypted digital airwave system (TETRA) in the UK has made it practically impossible for civilians to listen to police radio.
In the United States, police departments, sheriff's departments, and state police often run their own systems in parallel, presenting interoperability problems. The Federal Communications Commission assigns licenses to these entities in the public safety (PP and PX) allotments of the spectrum. These include allocations in the lower portion of the VHF spectrum (around 39–45 MHz), highly susceptible to "skip" interference but still used by state highway patrols; the VHF "hi-band", from 150–160 MHz; and various UHF bands. Many systems still use conventional FM transmissions for most traffic; others are trunked analog or digital systems. Recently, there has been a move towards digital trunked systems, especially those based around the public-safety standard Project 25 format set by the Association of Public-Safety Communications Officials-International. A minority of other police radio systems, the largest examples being the Milwaukee Police Department and Pennsylvania State Police, use the incompatible OpenSky format. TETRA, the standard in many European countries as well as other places in the world, is virtually unused in the United States.
Some states operate statewide radio networks with varying levels of participation from police on the county and city levels:
It is generally legal in the United States to listen to unencrypted police communications, though some states and municipalities prohibit carrying receivers within vehicles.
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code.
In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some types of repeaters broadcast an identical signal, but alter its method of transmission, for example, on another frequency or baud rate.
In radio communication, a transceiver is an electronic device which is a combination of a radio transmitter and a receiver, hence the name. It can both transmit and receive radio waves using an antenna, for communication purposes. These two related functions are often combined in a single device to reduce manufacturing costs. The term is also used for other devices which can both transmit and receive through a communications channel, such as optical transceivers which transmit and receive light in optical fiber systems, and bus transceivers which transmit and receive digital data in computer data buses.
Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz ; above the medium frequency band (MF), to the bottom of the VHF band.
Wireless communication is the transfer of information (telecommunication) between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most common wireless technologies use radio waves. With radio waves, intended distances can be short, such as a few meters for Bluetooth, or as far as millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mouse, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications involve other electromagnetic phenomena, such as light and magnetic or electric fields, or the use of sound.
A two-way radio is a radio transceiver, which is used for bidirectional person-to-person voice communication with other users with similar radios, in contrast to a broadcast receiver, which only receives transmissions.
A scanner is a radio receiver that can automatically tune, or scan, two or more discrete frequencies, stopping when it finds a signal on one of them and then continuing to scan other frequencies when the initial transmission ceases.
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, adding the ability to transfer data as well as voice 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 trunked radio system is a two-way radio system that uses a control channel to automatically assign frequency channels to groups of user radios. In a traditional half-duplex land mobile radio system a group of users with mobile and portable two-way radios communicate over a single shared radio channel, with one user at a time talking. These systems typically have access to multiple channels, up to 40-60, so multiple groups in the same area can communicate simultaneously. In a conventional (non-trunked) system, channel selection is done manually; before use, the group must decide which channel to use, and manually switch all the radios to that channel. This is an inefficient use of scarce radio channel resources because the user group must have exclusive use of their channel regardless of how much or how little they are transmitting. There is also nothing to prevent multiple groups in the same area from choosing the same channel, causing conflicts and 'cross-talk'. A trunked radio system is an advanced alternative in which the channel selection process is done automatically, so as to avoid channel conflicts and maintain frequency efficiency across multiple talkgroups. This process is handed by what is essentially a central radio traffic controller, a function automatically handled by a computer system.
A mobile phone jammer or blocker is a device which deliberately transmits signals on the same radio frequencies as mobile phones, disrupting the communication between the phone and the cell-phone base station, effectively disabling mobile phones within the range of the jammer, preventing them from receiving signals and from transmitting them. Jammers can be used in practically any location, but are found primarily in places where a phone call would be particularly disruptive because silence is expected, such as entertainment venues.
A radio listening station is a facility used for military reconnaissance, especially telecommunications reconnaissance by "intercepting" radio transmitter communications. In contrast to the original eavesdropping on an acoustic speech conversation, radio eavesdropping stations are used to eavesdrop on the information transmitted wirelessly using radio technology. For this purpose, highly sensitive radio receivers and suitable receiving antennas are used.
Telenor Kystradio is a part of Telenor and provides maritime telecommunication services along the coast of Norway, operating networks of marine VHF radio, medium frequency, high frequency and Navtex transmitters. As of January 2018 there are two coastal radio stations in Norway, Kystradio nord and Kystradio sør. The agency also issues marine radio licenses for both commercial- and pleasure ships, including callsigns and Maritime Mobile Service Identities, as well as radio operator certificates. Telenor Kystradio head office is based at Telenor Norway's head office at Fornebu. Telenor Kystradio also performs GMDSS Radio inspections, and are approved by the Norwegian Maritime Authority as well as most mayor classification authorities. The Radioinspeksjonen is located in Oslo, Stavanger, Bergen, Ålesund, Sandnessjøen, Bodø, Lofoten and Troms.
ASTRO 25 is a generation of ASTRO digital two-way radio communications by Motorola Solutions. Motorola first introduced digital two-way radio in the U.S. in 1991 under the name ASTRO Digital Solutions.
A wireless intercom is a telecommunications device that enables voice communication without the need to run copper wires between intercom stations. A wired intercom system may incorporate wireless elements.
Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates oscillating electrical energy, often characterized as a wave. They can be received by other antennas connected to a radio receiver, this is the fundamental principle of radio communication. In addition to communication, radio is used for radar, radio navigation, remote control, remote sensing, and other applications.
The Indian Telegraph Act, 1885 was the enabling legislation in India which governed the use of wired and wireless telegraphy, telephones, teletype, radio communications and digital data communications. It gives the Government of India exclusive jurisdiction and privileges for establishing, maintaining, operating, licensing and oversight of all forms of wired and wireless communications within Indian territory. It also authorizes government law enforcement agencies to monitor/intercept communications and tap phone lines under conditions defined within the Indian Constitution. The act came into force on 1 October 1885. Since that time, numerous amendments have been passed to update the act to respond to changes in technology.
The National Interoperability Field Operations Guide (NIFOG) is a technical reference for emergency communication planning and for radio technicians responsible for radios that will be used in disaster response.
Rohde & Schwarz GmbH & Co KG is an international electronics group specializing in the fields of electronic test equipment, broadcast & media, cybersecurity, radiomonitoring and radiolocation, and radiocommunication. The company provides also products for the wireless communications, electronics industry, aerospace and defense, homeland security and critical infrastructures.
In police terminology, a beat is the territory that a police officer is assigned to patrol. Beats are used to effectively divide available officers across a law enforcement agency's jurisdiction, ensuring organized police presence across a wide area.
The Norwegian Public Safety Network is a public safety network system based on Terrestrial Trunked Radio (TETRA). Nødnett is implemented by the Directorate for Emergency Communication. The network is primarily used for internal and interdisciplinary communication by the police, fire departments and health services. Nødnett is also used by several organisations participating in rescue and emergency work. Planning of the network started in 1995 and in 2006 the contract to build it was awarded to Nokia Siemens Networks. As Nokia Siemens Networks was unable to complete the contract, it was passed on to Motorola Solutions in 2012. The critical infrastructure of Nødnett was finished and was operational in all districts of mainland Norway by December 1, 2015.