39 lines
1.4 KiB
Markdown
39 lines
1.4 KiB
Markdown
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---
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tags: [radio]
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created: Sunday, July 06, 2025
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---
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# Radio basics
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Radio is the technology of communication or exchanging information using radio
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waves.
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Radio waves are electromagnetic waves that transmit at a certain frequency of
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the [electromagnetic spectrum](./Electromagnetism.md): between 3Hz and 300GHz.
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This makes them the lowest in frequency and the longest in wavelength.
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Radiowaves are generated by an electronic device called a **transmitter**, which
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is connected to an **antenna** which radiates the waves out into space.
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These waves can be detected by another antenna connected to a radio
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**receiver**.
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Information is transmitted by adding information to the raw electromagnetic
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wave. The wave by itself doesn not contain any information.
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The wave form used is a sine wave that fluctuates smoothly and consistently.
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There are two main methods of adding information to the waveform: AM and FM.
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AM stands for **amplitude modulation**. Here, the amplitude of the wave is
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altered. The amplitude is the distance from peak to peak. For example, the sine
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wave produced by a person's voice is overlaid onto the transmitter's sine wave
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to vary its amplitude.
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FM stands for **frequency modulation**. Here, the frequency of the wave is
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altered. The frequency is the number of oscillations over a given time period
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which we measure in Hertz.
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