Scanner

Uniden BCT-15 base/mobile trunktracking scanner

Uniden BCD396T handheld trunktracking scanner

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. The terms radio scanner or police scanner generally refer to a communications receiver that is primarily intended for monitoring VHF and UHF landmobile radio systems, as opposed to, say, a receiver used to monitor international shortwave transmissions.

More often than not, these scanners can also tune to different types of modulation 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 radio systems and decode APCO-P25 digital 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 and crime investigation, 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 setting and resume scanning other frequencies when that activity ceases.

Scanners are used by hobbyists, railfans, off duty emergency services personnel, criminals and reporters.

Scanners first became popular and widely available during CB Radio's heyday in the 1970s. The first scanners often had between four and ten channels and required the purchase of a separate crystal for each frequency received. Modern programmable scanners 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 microprocessors.

A hand-held wide band communications receiver.

Many recent models will allow scanning of the specific DCS or CTCSS code used on a specific frequency should it have multiple users. One memory bank can be assigned to air traffic control, another can be for local marine 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 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 All Ohio Scanner Club, Chicago Area Radio Monitoring Association and RadioReference.com are examples of these.

Legal issues in the US

New York and Florida currently prohibit scanners installed in a vehicle unless the operator has an FCC issued radio license

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 systems and demodulating some digital radio systems such as APCO Project 25 are available, decryption-capable scanners would be a violation of United States law and possibly laws of other countries.^{[citation needed]}

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.^[1] This law remains in effect even though few cellular subscribers still use analogue technology. There are Canadian and European unblocked versions available, but these are illegal to import into the U.S. Frequencies used by early cordless phones 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 FCC (Amateur Radio, etc.)^[2][3] or the operator's job requires the use of a scanner in a vehicle (e.g., police, fire, utilities).^{[citation needed]}

Canada allows any analog transmission to be monitored, but content of the communication may not be disclosed. 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.^[4] Other countries^{[which?][clarification needed]} consider possession of a scanner at any time an offense.^{[citation needed]}

In the United States, the general guidelines^{[clarification needed]} to follow when using a radio scanner are that it is illegal to:^{[citation needed]}

• 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^{[citation needed]} 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 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).^[5][6]

Legal issues in other countries

• New Zealand: According to the 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 (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.

See also

Electronics portal

• Two-way radio
• Trunked radio system
• Communications receiver
• Chicago Area Radio Monitoring Association

References

External links

Radio frequency sources

There are numerous websites which provide lists of frequencies for emergency services and businesses in various areas of the world. These are among the most prominent.

• Global Frequency Database
• Frequency Database for Germany (English/German)
• Frequency Database for Ireland.
• Police-Scanner.info - The Police Scanner Info-Portal
• PoliceScanners.net Information Resource for US scanner frequencies
• ScannerMaster's Information and reviews of many scanners
• RadioReference A very comprehensive source of frequencies in the United States.
• Scanning New Zealand
• United States Federal Communications Commission FCC searchable database of licensed radio frequencies
• Australian Communications and Media Authority ACMA searchable database of licensed frequencies and users
• FlightRadio.com - Aircraft frequencies for your scanner.
• AirNav - Airports
• Freq of Nature
• Scanning In Tasmania, Australia
• Monitoring Times Milcom Blog A Radio related blog with military frequencies, callsigns and communications news (including milsat info/frequencies).
• NF2G Scannist Pages A list of frequencies for New York State maintained by Dave Stark, NF2G.
• CARMA (Chicago Area Radio Monitoring Association)
• National Communications Magazine (NAT-COM)

Scanner manufacturers

• AOR (Authority on Radio Communications)
• Uniden under the Bearcat brand, but also OEM under Radio Shack brand in the United States
• Icom US, CA, AU, NZ
• GRE (formerly exclusively OEM's for Radio Shack in the United States, but as of 2007 also as the "GRE-COM" brand)
• GRE America, Inc. (USA office for "GRECOM" brand)

Scanner laws

• Mobile Scanner & RADAR Detector Laws in the U.S.
• Radio Communications Legislation in Australia - including the use of scanners

Other links

• RadioReference.com's Information Wiki
• Radio scanner forums and frequencies for Ireland
• Dallas-Fort Worth Metroplex Scanning
• Information and a database related to radio scanning in Ireland (1400 frequencies)
• A FAQ for scanner users
• A beginner's guide to scanning radios
• Incident Broadcast Network - Listen to live scanner feeds from around the USA and the world, for free!
• Radio Scanner Programming Service
• ScannerFeeds.us - Online scanner directory containing 1300+ links.
• Great Falls MT Area live scanner feed and information
• Evansville IN police scanner LIVE
• Pinellas County Florida - Live scanner feed from Clearwater Florida to St. Petersburg. Including EMS, Fire,and Police
• Harvard University Police Department frequencies scanner
• Yuba/Sutter/Colusa Tri-County Public Safety Network - Live scanner feed broadcast from the Central Sacramento Valley in California

Wikimedia Commons has media related to: Scanners