science

PMR446

PMR446 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 PMR446 rather than just read about it. In short: PMR446 (Private Mobile Radio, 446 MHz) is a licence-exempt personal radio service in the UHF radio frequency band, available for business and personal use in most countries throughout the European Union, Malaysia, Singapore, Norway, the United Arab Emirates, and the United Kingdom. PMR446 is typically used for small-site, same-building and line of sight outdoor activities.

Key takeaways

PMR446 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PMR446 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PMR446 from memory before moving on to harder problems.

Reference excerpt

PMR446 (Private Mobile Radio, 446 MHz) is a licence-exempt personal radio service in the UHF radio frequency band, available for business and personal use in most countries throughout the European Union, Malaysia, Singapore, Norway, the United Arab Emirates, and the United Kingdom. PMR446 is typically used for small-site, same-building and line of sight outdoor activities. Equipment use ranges from consumer-grade to professional quality walkie-talkies (similar to those used for FRS/GMRS in the United States and Canada). Depending on surrounding terrain, range can vary from a few hundred metres (yards) (in a city) to a few kilometres (miles) (flat countryside) to many kilometres (miles) from high ground. Historically, analogue FM is used but a digital voice mode has been available in radios conforming to digital private mobile radio (dPMR446) and digital mobile radio (DMR Tier 1) standards designed by ETSI. Originally 8 channels were available in analogue mode but this has now been increased to 16 channels. Typically PMR446 is used for both recreational and business use, additionally it has been utilized by amateur-radio operators and radio enthusiasts as a license-free experimental band.

History The first steps towards creating licence-free short range radio communications were taken in April 1997 when the European Radio Communications Committee decided on a 446 MHz frequency band to be used for the new radios. In November 1998, ERC Decision (98)25 allocated frequency band 446.000–446.100 MHz for analogue PMR446; another two decisions established licence exemption for PMR446 equipment and free circulation of the PMR446 equipment. The first country which introduced these frequencies for licence-free use was Ireland on 1 April 1998. The United Kingdom introduced PMR446 service in April 1999; since 2003, it has replaced the former short-range business radio (SRBR) service. In October 2005, ECC Decision (05)02 added unlicensed band 446.1–446.2 MHz for use by digital DMR/dPMR equipment. In July 2015, ECC Decision (15)05 doubled the number of analog channels to 16 by extending analog operation onto the 446.1–446.2 MHz band previously used by digital DMR/dPMR equipment, effective January 2016; from January 2018, the number of digital channels was doubled by extending onto the 446.0–446.1 MHz band used by analog FM.

Range Until recently, PMR446 radios were handheld transceivers with fixed antennas (see Technical information). In November 2015, Midland Radio announced the release of the GB1 mobile PMR446 radio for vehicular use. The range of PMR446, just like any VHF or UHF radio, is dependent on many factors like environment (in-city range is far less than in an open field), height above surrounding obstructions, and, to a lesser extent, weather conditions. The antenna type and location, transmit power and receive sensitivity also affect range. However, with PMR446 most of these variables are fixed at manufacturing to comply with the PMR446 specifications. Most of the time the maximum range that a user in a city can expect is a few hundred metres (yards) or less. Range may be many kilometres (miles), for example between hilltops, or only a few hundred metres (yards), if for example a hill or large metal object is in the transmission path between radios. The best known long-distance record is 333 mi (536 km) from Blyth in the United Kingdom to Almere, Netherlands. This was the result of enhanced propagation conditions, not a line-of-sight signal.

Use worldwide PMR446-compliant equipment may be used anywhere throughout Europe, Malaysia, and Singapore. Type approved PMR446 radios with power up to 500 mW can be used without any licence in India and Vietnam. The devices may not be base stations or repeaters, and must use integrated antennas only. PMR446 radios use frequencies that in Australia, the U.S., and Canada are allocated to amateur radio operators, and military radar systems. Instead, the U.S., Canada and Mexico use the Family Radio Service (FRS) system, which provides a similar service on different frequencies, around 462 and 467 MHz. These frequencies are allocated to the emergency services in Europe, notably the fire brigade in the UK, police in Russia and commercial users in Australia. Interference with licensed radio services may result in prosecution. Australia, New Zealand, Vanuatu use the UHF Citizen's Band system in the 476–477 MHz range and a maximum power output of 5 W giving improved range over the lower power PMR system.

Technical information PMR446 covers band 446.0–446.2 MHz. The general ECC decision however still requires integral antennas and the actual implementation varies between different countries.

Analogue FM and digital TDMA

Analogue PMR446 uses 16 FM channels separated by 12.5 kHz from each other. Maximum power is 500 mW ERP and equipment must be used on a mobile basis. CTCSS is usually used, with more upmarket models also featuring DCS and/or fixed-carrier voice inversion. Before January 2016, only the lower 8 channels were allowed for analog FM operation. For those older PMR446 radios with 39 codes, the codes 0 to 38 are CTCSS Tones:

For those newer PMR446 radios with 122 codes, codes 0 to 38 are as above while codes 39 to 121 are DCS codes:

Digital PMR446 DMR Tier I (TDMA) uses 16 digital voice channels separated by 12.5 kHz from each other with 4-level FSK modulation at 3.6 kbit/s. Before January 2018, only the higher 8 channels were allowed for digital TDMA operation. Some Digital PMR446 radios (Hytera BD305LF, Retevis RT40, ...) support Dual Capacity Direct Mode (DCDM), which allows for the use of two timeslots during simplex (radio-to-radio) communication. This effectively doubles the channel capacity by allowing two simultaneous transmissions on one channel. Color Code (0 to 16) is the equivalent of CTCSS for digital. It's used to isolate a population of users (a company, an association, a family, ...). By convention CC1 is used for public contact. TalkGroups are used to separate groups of users (ex: TG1 for direction and TG2 for room service in a hotel using channel 12 CC7). By contacting a specific TG, each user subscribing to this TG will hear you (Group Call). A user can subscribe to many TGs (RX Group List). It is also possible to contact all users in your color code (All Call). Radio ID One for each user, to be contacted directly (Private Call).

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with PMR446

Start with the simplest possible case. Write down what PMR446 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 PMR446 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 PMR446 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 PMR446

In research: PMR446 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 PMR446 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: PMR446 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bandplans, Radio hobbies, Radio regulations, so understanding it makes those chapters shorter.
In everyday life: Look for PMR446 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 PMR446 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PMR446 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 PMR446 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PMR446 in simple terms?

Why does PMR446 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 PMR446?

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 PMR446.