science

Public Radio Service

Public Radio Service 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 Public Radio Service rather than just read about it. In short: Public Radio Service (PRS) (Chinese: 公众对讲机; pinyin: Gōngzhòng duìjiǎngjī) is a walkie-talkie personal radio service in the mainland of China, Hong Kong and Macau, but excluding Taiwan. It can be used without a license, and no fees are charged for the use of the frequencies.

Key takeaways

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

Reference excerpt

Public Radio Service (PRS) (Chinese: 公众对讲机; pinyin: Gōngzhòng duìjiǎngjī) is a walkie-talkie personal radio service in the mainland of China, Hong Kong and Macau, but excluding Taiwan. It can be used without a license, and no fees are charged for the use of the frequencies. It uses 409 MHz. It is also known as PRS409. It is similar to the American and Canadian Family Radio Service (FRS) and PMR446 in the European Union.

Technical information The PRS radio channels use narrow-band frequency modulation (NBFM) with a maximum deviation of 2.5 kHz. The channels are spaced at 12.5 kHz intervals. They are limited to 500 milliwatts effective radiated power. PRS radios are not allowed to be used at airports and onboard aircraft. They are not allowed to be connected to the public switched telephone network or cellular network.

See also 70-centimeter band CDCSS Continuous Tone-Coded Squelch System (CTCSS) Family Radio Service (the equivalent of PRS in Canada, the US, and some other countries) General Mobile Radio Service KDR 444 LPD433 Multi-Use Radio Service Personal radio service Personal radio service#Taiwan UHF CB

Notes

References

Worked examples

Example 1 — a first encounter with Public Radio Service

Start with the simplest possible case. Write down what Public Radio Service 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 Public Radio Service 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 Public Radio Service 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 Public Radio Service

In research: Public Radio Service 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 Public Radio Service 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: Public Radio Service 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 Public Radio Service 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 Public Radio Service in 20 minutes

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

Frequently asked questions

What is Public Radio Service in simple terms?

Why does Public Radio Service 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 Public Radio Service?

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 Public Radio Service.