Scanner (radio)
Encyclopedia
A scanner is a radio
Radio
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...

 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...

 that can automatically tune, or scan, two or more discrete frequencies
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

, stopping when it finds a signal on one of them and then continuing to scan other frequencies when the initial transmission ceases.

The terms radio scanner or police scanner generally refer to a communications receiver that is primarily intended for monitoring VHF
Very high frequency
Very high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...

 and UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...

 landmobile radio systems, as opposed to, say, a receiver used to monitor international shortwave
Shortwave
Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...

 transmissions.

More often than not, these scanners can also tune to different types of modulation
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...

 as well (AM, FM, WFM, etc). Early scanners were slow, bulky, and expensive. Today, modern microprocessors have enabled scanners to store thousands of channels and monitor hundreds of channels per second. Recent models can follow trunked
Trunked radio system
A trunked radio system is a complex type of computer-controlled radio system. Trunked systems use a few channels , and can have virtually unlimited talkgroups. The control channel computer sends packets of data to enable one talkgroup to talk together, regardless of frequency...

 radio systems and decode APCO-P25 digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...

 transmissions. Both hand held and desktop models are available. Scanners are often used to monitor police, fire and emergency medical services. Radio scanning serves an important role in the fields of journalism
Journalism
Journalism is the practice of investigation and reporting of events, issues and trends to a broad audience in a timely fashion. Though there are many variations of journalism, the ideal is to inform the intended audience. Along with covering organizations and institutions such as government and...

 and crime investigation
Crime
Crime is the breach of rules or laws for which some governing authority can ultimately prescribe a conviction...

, as well as a hobby for many people around the world.

History and use

Scanners developed from earlier tunable and fixed-frequency radios that received one frequency at a time. Non-broadcast radio systems, such as those used by public safety agencies, do not transmit continuously. With a radio fixed on a single frequency, much time could pass between transmissions, while other frequencies might be active. A scanning radio will sequentially monitor multiple programmed channels, or search between user defined frequency limits. The scanner will stop on an active frequency strong enough to break the radio's squelch
Squelch
In telecommunications, squelch is a circuit function that acts to suppress the audio output of a receiver in the absence of a sufficiently strong desired input signal.-Carrier squelch:...

 setting and resume scanning other frequencies when that activity ceases.

Scanners are used by hobbyists, railfan
Railfan
A railfan or rail buff , railway enthusiast or railway buff , or trainspotter , is a person interested in a recreational capacity in rail transport...

s, off duty emergency services personnel, reporters, and criminals.

Scanners first became popular and widely available during CB Radio
Citizens' band radio
Citizens' Band radio is, in many countries, a system of short-distance radio communications between individuals on a selection of 40 channels within the 27-MHz band. Citizens' Band is distinct from the FRS, GMRS, MURS and amateur radio...

's heyday in the 1970s. The first scanners often had between four and ten channels
Channel (communications)
In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...

 and required the purchase of a separate crystal
Crystal oscillator
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency...

 for each frequency received. Modern programmable scanners – an early 1976 US entry was the Tennelec
Tennelec
Tennelec was a US electronics company founded in the early 1960s by Edward Fairstein in Oak Ridge, Tennessee. The company came to prominence producing instrumentation for nuclear studies and later, programmable scanning radios....

 MCP-1 – allow hundreds or thousands of frequencies to be entered via a keypad and stored in various 'memory banks' and can scan at a rapid rate due to modern microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

s. Many recent models will allow scanning of the specific DCS
DCS
-Education:*Dade Christian School A private school in Miami-Dade county*Dayton City School, a school in Dayton Tennessee*Dean Close School*Dearborn Christian School A private school in Dearborn, Michigan*Desert Christian Schools, in Tucson, Arizona...

 or CTCSS
CTCSS
In telecommunications, Continuous Tone-Coded Squelch System or CTCSS is a circuit that is used to reduce the annoyance of listening to other users on a shared two-way radio communications channel. It is sometimes called tone squelch...

 code used on a specific frequency should it have multiple users. One memory bank can be assigned to air traffic control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...

, another can be for local marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 communications, and yet another for local police frequencies. These can be switched on and off depending on the user's preference. Most scanners have a weather radio band, allowing the listener to tune into weather radio broadcasts
NOAA Weather Radio All Hazards
NOAA Weather Radio All Hazards is a network of radio stations broadcasting continuous weather information directly from a nearby National Weather Service office. It is operated by the NWS, an agency of the National Oceanic and Atmospheric Administration within the United States Department of...

 from a NOAA transmitter.

Some scanners are equipped with Fire-Tone out. Fire tone out decodes Quik call II tones and acts as a pager when the correct sequence of tones is detected.

Active frequencies can be found by searching the internet and frequency reference books or can be discovered through a programmable scanner's search function. An external antenna for a desktop scanner or an extendable antenna for a hand held unit will provide greater performance than the original equipment antennas provided by manufacturers.

Many scanner clubs exist to allow members to share information about frequencies, codes and operations. Most have Internet presence, such as websites, email lists or Web forums. The Southern California Monitoring Association (SCMA), The All Ohio Scanner Club, Chicago Area Radio Monitoring Association
Chicago Area Radio Monitoring Association
The Chicago Area Radio Monitoring Association is a scanner radio club in the Chicago metropolitan area. Membership is free and unofficial, there are no dues or membership certificates. About 1400 people are members of the mailing list or participate in other activities...

 and RadioReference.com are examples of these.

Legal issues in the US

The legality of radio scanners varies considerably between jurisdictions. In the United States it is a federal crime to monitor cellular phone calls. Some US states prohibit the use of a scanner in an automobile. Although scanners capable of following trunked radio system
Trunked radio system
A trunked radio system is a complex type of computer-controlled radio system. Trunked systems use a few channels , and can have virtually unlimited talkgroups. The control channel computer sends packets of data to enable one talkgroup to talk together, regardless of frequency...

s and demodulating some digital radio systems such as APCO Project 25 are available, decryption-capable scanners would be a violation of United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 law and possibly laws of other countries.

A law passed by the Congress of the United States, under the pressure from cellular telephone interests, prohibited scanners sold after a certain date from receiving frequencies allocated to the Cellular Radio Service. The law was later amended to make it illegal to modify radios to receive those frequencies, and also to sell radios that could be easily modified to do so. This law remains in effect even though few cellular subscribers still use analogue
Analog signal
An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...

 technology. There are Canadian
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an unblocked versions available, but these are illegal to import into the U.S. Frequencies used by early cordless phone
Cordless telephone
A cordless telephone or portable telephone is a telephone with a wireless handset that communicates via radio waves with a base station connected to a fixed telephone line, usually within a limited range of its base station...

s at 43.720–44.480 MHz, 46.610–46.930 MHz, and 902.000–906.000 MHz can be picked up by many scanners. The proliferation of scanners led most cordless phone manufacturers to produce cordless handsets operating on a more secure 2.4 GHz system using spread-spectrum technology. Certain states in the U.S., such as New York and Florida, prohibit the use of scanners in a vehicle unless the operator has a radio license issued from the Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...

 (FCC) (Amateur Radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...

, etc.) or the operator's job requires the use of a scanner in a vehicle (e.g., police, fire, utilities).

In some parts of the United States, there are extra penalties for the possession of a scanner during a crime, and some states, such as Michigan, also prohibit the possession of a scanner by a person who has been convicted of a felony in the last 5 years.

In the United States, the general guidelines to follow when using a radio scanner are that it is illegal to:
  • listen in on cellular and cordless phone calls
  • intercept encrypted or scrambled communications
  • sell or import radio scanners that are capable of receiving cellular phone frequencies (this rule does not apply to sales by individuals and radio scanners made before the ban)
  • modify radio scanners so that cellular phone frequencies can be received
  • use information received for personal gain (a common example is where a taxi driver listens to a competitor's dispatch channel to steal a customer)
  • use information received to aid in the commission or execution of a crime
  • disclose information received to other persons

Licensed Amateur Radio Operators with a valid FCC License may possess Amateur Radio Transceivers capable of reception beyond the Amateur Radio Bands per an FCC Memorandum & Order known as FCC Docket PR91-36 (also known as FCC 93-410).

Florida

843.16 Unlawful to install or transport radio equipment using assigned frequency of state or law enforcement officers; definitions; exceptions; penalties.--
(1) A person, firm, or corporation may not install or transport in any motor vehicle or business establishment, except an emergency vehicle or crime watch vehicle as herein defined or a place established by municipal, county, state, or federal authority for governmental purposes, any frequency modulation radio receiving equipment so adjusted or tuned as to receive messages or signals on frequencies assigned by the Federal Communications Commission to police or law enforcement officers or fire rescue personnel of any city or county of the state or to the state or any of its agencies. Provided, nothing herein shall be construed to affect any radio station licensed by the Federal Communications System or to affect any recognized newspaper or news publication engaged in covering the news on a full-time basis or any alarm system contractor certified pursuant to part II of chapter 489, operating a central monitoring system.
(3) This section does not apply to the following:
(a) Any holder of a valid amateur radio operator or station license issued by the Federal Communications Commission.
(b) Any recognized newspaper or news publication engaged in covering the news on a full-time basis.
(c) Any alarm system contractor certified pursuant to part II of chapter 489, operating a central monitoring system.
(d) Any sworn law enforcement officer as defined in s. 943.10 or emergency service employee as defined in s. 496.404 while using personal transportation to and from work.
(e) An employee of a government agency that holds a valid Federal Communications Commission station license or that has a valid agreement or contract allowing access to another agency's radio station.
(4) Any person, firm, or corporation violating any of the provisions of this section commits a misdemeanor of the first degree, punishable as provided in s. 775.082 or s. 775.083.

Indiana

Interference With Governmental Operations s. 35-44-3-12—Possession of police radios -- (a) A person who knowingly or intentionally: (1) Possesses a police radio; (2) Transmits over a frequency assigned for police emergency purposes; or (3) Possesses or uses a police radio:
(A) While committing a crime; (B) To further the commission of a crime; or (C) To avoid detection by a law enforcement agency; commits unlawful use of a police radio, a Class B misdemeanor.
(b) Subsection (a)(1) and (a)(2) do not apply to:
(1) A governmental entity; (2) A regularly employed law-enforcement officer; (3) A common carrier of persons for hire whose vehicles are used in emergency service; (4) A public service or utility company whose vehicles are used in emergency service; (5) A person who has written permission from the chief executive officer of a law enforcement agency to possess a police radio; (6) A person who holds an amateur radio license issued by the Federal Communications Commission if the person is not transmitting over a frequency assigned for police emergency purposes; (7) A person who uses a police radio only in the person's dwelling or place of business; (8) A person: (A) Who is regularly engaged in newsgathering activities; (B) Who is employed by a newspaper qualified to receive legal advertisements under IC 5-3-1, a wire service, or a licensed commercial or public radio or television station; and (C) Whose name is furnished by his employer to the chief executive officer of a law enforcement agency in the county in which the employer's principal office is located; (9) A person engaged in the business of manufacturing or selling police radios; or (10) A person who possesses or uses a police radio during the normal course of the person's lawful business.

Kentucky

Kentucky Revised Statute (K.R.S.) 432.570, which states that, "it shall be unlawful for any person except a member of a police department or police force or an official with written authorization from the head of a department which regularly maintains a police radio system authorized or licensed by the Federal Communications Commission, to have in his or her possession or in an automobile or other vehicle, or to equip install in or on any automobile or other vehicle, any mobile radio set or apparatus capable of either receiving or transmitting radio or other messages or signals within the wave length or channel now or which may hereafter be allocated by the Federal Communications Commission or its successor, for the purpose of police radios, or which may in any way intercept or interfere with the transmission of radio messages by any police or other peace officers.

Minnesota

299C.37 POLICE COMMUNICATION EQUIPMENT; USE, SALE. Subdivision 1.Use regulated.
(a) No person other than peace officers within the state, the members of the State Patrol, and persons who hold an amateur radio license issued by the Federal Communications Commission, shall equip any motor vehicle with any radio equipment or combination of equipment, capable of receiving any radio signal, message, or information from any police emergency frequency, or install, use, or possess the equipment in a motor vehicle without permission from the superintendent of the bureau upon a form prescribed by the superintendent.

Canada

According to the Radiocommunication Act
Radiocommunication Act
The Radiocommunication Act is an Act of Parliament respecting radiocommunication in Canada.-External links:*...

, it is completely legal to install, operate or possess a radio apparatus that is capable only of the reception of broadcasting (digital and analog, but not encrypted data) provided that private information is not passed on or disclosed to any other person(s) or party(s).

New Zealand

According to the Radiocommunications Act 1989 it is legal to possess and use a scanner at any time to tune to any private voice radio (not encrypted data) provided that private information is not passed on or disclosed to any other person(s) or party(s).

Australia

It is legal to possess a scanner. It is legal to listen to any transmission that is not classified as telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

 (i.e. anything not connected to the telephone network).

Mexico

It is legal to have an unblocked scanner and listen to any radio spectrum frequencies including encrypted and cellular band. According to the Federal Law of General Ways of Communication individuals are prohibited from spreading any information obtained via the mass media.

Brazil

It is legal to have a scanner, but the user should have a ham radio license. Individuals are prohibited from spreading or recording any information obtained.

See also

  • Two-way radio
    Two-way radio
    A two-way radio is a radio that can both transmit and receive , unlike a broadcast receiver which only receives content. The term refers to a personal radio transceiver that allows the operator to have a two-way conversation with other similar radios operating on the same radio frequency...

  • Trunked radio system
    Trunked radio system
    A trunked radio system is a complex type of computer-controlled radio system. Trunked systems use a few channels , and can have virtually unlimited talkgroups. The control channel computer sends packets of data to enable one talkgroup to talk together, regardless of frequency...

  • Communications receiver
    Communications receiver
    A communications receiver is a type of radio receiver used as a component of a radio communication link.-Features:Commercial communications receivers are characterised by high stability and reliability of performance, and are generally adapted for remote control and monitoring...

  • Chicago Area Radio Monitoring Association
    Chicago Area Radio Monitoring Association
    The Chicago Area Radio Monitoring Association is a scanner radio club in the Chicago metropolitan area. Membership is free and unofficial, there are no dues or membership certificates. About 1400 people are members of the mailing list or participate in other activities...


Radio frequency sources


Scanner laws


Other links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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