science

Radio scanner

Radio scanner is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Radio scanner rather than just read about it. In short: A radio scanner or simply scanner is a radio receiver that can automatically tune discrete frequencies, scanning over a frequency band to find a signal until the initial transmission ceases. The term scanner generally refers to a communications receiver that is primarily intended for monitoring VHF and UHF landmobile radio systems, as opposed to, for instance, a receiver used to monitor international shortwave trans…

Key takeaways

Radio scanner belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Radio scanner to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Radio scanner from memory before moving on to harder problems.

Reference excerpt

A radio scanner or simply scanner is a radio receiver that can automatically tune discrete frequencies, scanning over a frequency band to find a signal until the initial transmission ceases. The term scanner generally refers to a communications receiver that is primarily intended for monitoring VHF and UHF landmobile radio systems, as opposed to, for instance, a receiver used to monitor international shortwave transmissions, although these may be classified as scanners too. More often than not, these scanners can also tune to different types of modulation as well (AM, FM, SSB, 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 digital transmissions such as APCO-P25, Digital mobile radio, NXDN, EDACS, and more. Both hand held and desktop models are available. Scanners are often used to monitor police, fire and emergency medical services. Radio scanning also 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 scan between user defined frequency limits and user defined frequency steps. 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 first became popular and widely available during the popularity height of CB radio 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. A US patent was issued to Peter W. Pflasterer on June 1, 1976. An early 1976 US entry was the Tennelec MCP-1, sold at the January 1976 Consumer Electronics Show in Chicago.

Features

Many recent models will allow scanning of the specific DCS or CTCSS code used on a specific frequency should it have multiple users. Memory banks are also common. For example, 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 also have a weather radio band, allowing the listener to tune into weather radio broadcasts from a NOAA transmitter. The weather function may also include S.A.M.E. (Specific Area Message Encoding) capability, this allows users to only receive alerts for specific counties that are programmed via the keypad. Some scanners are equipped with Fire-Tone out. Fire tone out decodes Quick Call type tones and acts as a pager when the correct sequence of tones is detected. Modern 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 for activity due to modern microprocessors. Active frequencies can be found by searching the internet and frequency reference books or can be discovered through a programmable scanner's search function. Antenna modifications may be used. For example, an external antenna can be used for a desktop scanner or an extendable antenna for a hand held unit will provide greater performance than the original equipment "stock" antennas provided by manufacturers.

Uses Scanners are often used by hobbyists, railfans, aviation enthusiasts, auto race fans, siren enthusiasts, off-duty emergency services personnel, and reporters. Many scanner clubs exist to allow members to share information about frequencies, codes, and operations. Many have internet presence, such as websites, email lists or web forums.

Legislation

Australia It is legal to possess a scanner in Australia and to listen to any transmission that is not classified as telecommunication (i.e. anything not connected to the telephone network). Phone app police scanners are also legal.

Austria Possession of a radio scanner is legal. However, article 93 of the Telekommunikationsgesetz prohibits the intentional reception of signals by third parties without authorization from the user.

Brazil In Brazil, it is legal to have a scanner, but the user is required to have an amateur radio license. Individuals are prohibited from spreading or recording any information obtained through scanning.

Belgium In Belgium it is allowed to possess and listen to a scanner. Although it is only allowed to listen to frequencies where you have a permission to listen to. Without permission it is only allowed to listen to HAM Radio or other so called 'free to listen' channels

Canada A situation that occurred in the Toronto area on 28 June 2011 involving York Regional Police officer Constable Garrett Styles was picked up by scanners. Online streaming of communications between the fatally injured officer and police dispatch were picked up by local media. The tragedy was widely reported before the officer's family was notified and several media outlets rebroadcast the recorded emergency transmission. A police initiative pressuring the government to create legislation to stop online streaming of scanner captured police communications was announced in April 2012. Although it is currently legal to stream information from a scanner in Canada, using the information for profit is not legal. Some Canadian police forces use encrypted communications which cannot legally be decrypted and streamed onto the Internet. Applications are available permitting anyone with an Internet-ready computer or smartphone to access scanner communications that are streamed onto the Internet by private individuals who possess the appropriate scanner and computer equipment.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Radio scanner

Start with the simplest possible case. Write down what Radio scanner claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Radio scanner before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Radio scanner ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Radio scanner

In research: Radio scanner appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Radio scanner in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Radio scanner is common in secondary-school and first-year university syllabi. It links to neighbouring topics Radio hobbies, Receiver (radio), so understanding it makes those chapters shorter.
In everyday life: Look for Radio scanner outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Radio scanner in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Radio scanner means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Radio scanner out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Radio scanner in simple terms?

Why does Radio scanner matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Radio scanner?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Radio scanner.