guided = wire
unguided = wireless
Radio link types
- terrestrial microwave (have microwave towel)
- LAN (WiMax)
- wide-area (cell phone)
- satellite (Geosynchronous orbit)
Data
- Analog data (continuous - voice)
- Digital data (discrete - data in computer (0 and 1))
Data(from computer) must be transformed to electromagnetic signals (use to carry along medium) and signals can also be analog(infinite number) and digital(limited number).
Can't send data without signal and cam combine to 4 combination
- analog data, analog signal
- analog data , digital signal
- digital data, analog signal
- digital data, digital signal
Periodic analog signals (look the same every period)
A sine wave is fundamental periodic analog signal that use in data comm.
- Peak amplitude
- frequencies (number of wave in 1 signal, number of wave in 1 sec. - Hz)
- period (represent time of 1 wave, sec)
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