48 lines
1.6 KiB
Markdown
48 lines
1.6 KiB
Markdown
# 1. Physical Layer
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This layer is responsible for the actual physical transfer of data between devices via cables or other mediums using switches, routers, etc..
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This layer also converts the data into a bit-stream of 1's and 0's.
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The signal convention must be the same on both devices. (Meaning of a 0 and a 1)
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## In depth
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Information on computers is stored in a digital format. To transmit this information we have to convert the information to signals.
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Physical layer is responsible for this conversion. The Physical layer deals with the actual physical transmission of electrical signals.
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You could say the physical layer is a bridge between real life and software.
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## Waves
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Waves, like you would see on a lake, or in electrical cables are made when a physical quantity changes in the form of a moving ridge.
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Waves by them self store no real information.
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## Signal
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A signal is a wave (carrier) that holds information. (wave + data = signal)
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The carrier is a type of wave we add our information to. In most cases a sine wave is used as a carrier wave,
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![[encoder.png]]
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A encoder converts analog or digital information in signals that can be transmitted across different [[Comminucation Mediums]]
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The process of adding data to a carrier wave is called Modulation
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## Modulation
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Adding data to carrier waves is called modulation.
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This can be done in 3 different ways.
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### Amplitude
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![[modulation-amplitude.png]]
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Amplitude or the strength (height) of a wave changes over time.
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We can change how much the amplitude is changing in a specific moment in time.
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### Frequency
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![[modulation-frequency.png]]
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Frequency can be changed
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### Phase |