Flashcards
P5E Satellite Communication
Flashcards do conjunto (11)
- 1What type of waves are used to communicate with satellites in a low polar orbit and what type are used for waves with a high geostationary orbit?Low frequency radio waves are used for low orbit satellites and higher frequency radio waves are used for geostationary satellites.
- 2Describe two features of a radio waveThey have a low frequency and very long wavelength.
- 3Radio waves with a frequency below what MHz are reflected by the ionosphere?30MHz
- 4Radio waves with a frequency above what GHz are reduced in strength because they are absorbed and scattered by rain, dust and other effects in the atmosphere?30GHz
- 5Radio waves between what frequencies can pass through the Earth's atmosphere/30MHz and 30GHz
- 6What type of signals are used in satellite communication and why?Digital signals are used because they are less likely to suffer from interference than analogue signals.
- 7What other type of waves are used to transmit information to satellites?Microwaves - they have a shorter wavelength and higher frequency than radio waves.
- 8Why does the dish used in satellite communication have to be many times larger than the wavelength when using microwaves?So that the waves are captured and focus onto the receiver. Microwaves have a very short wavelength which means they are not likely to be diffracted so the beam remains narrow and focused. This is why also the transmitter and receiver have to be well aligned.
- 9How is diffraction useful?It is useful because it means that radio waves can get around obstacles. So if there is a hill in the way then it will not affect the signal.
- 10What are the types of diffraction and what they look like?pg78 for diagrams and types
- 11The amount that a wave is diffracted by depends on the size of the gap and the wavelength of the wave. What do large gaps do and when does maximum diffraction happen?Large gaps simply allow the wave to pass straight through without diffracting much.
Maximum diffraction happens when the size of the gap is equal to the wavelength.
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- O usuário eliminou as informações de disciplina FlashCards sobre P5E Satellite Communication, criado por Usuário eliminado em 19-03-2017.
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- Usuário eliminado · mar 2017
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- 19 mar 2017
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- Criado por James Middleton4075 · 31 mar 2015
- Copiado por Nuttapon Nakarach · 19 mar 2017
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