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Discuss how longwave (LW), shortwave (SW) and microwave links can be used to communicate beyond the visible horizon - AQA - A-Level Physics - Question 5 - 2017 - Paper 8
Question 5
Discuss how longwave (LW), shortwave (SW) and microwave links can be used to communicate beyond the visible horizon. For each link, you should give: - a typical ca... show full transcript
Worked Solution & Example Answer:Discuss how longwave (LW), shortwave (SW) and microwave links can be used to communicate beyond the visible horizon - AQA - A-Level Physics - Question 5 - 2017 - Paper 8
Step 1
Longwave (LW)
Answer
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Typical Carrier Frequency: Longwave links typically use frequencies in the range of 150 kHz to 300 kHz.
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Signal Travel Explanation: Longwave signals travel by reflecting off the ground, allowing them to cover long distances. The ground affects the propagation, and signals can travel well beyond the line of sight.
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Typical Use: An application of longwave communication is national time signals, which provide accurate time information over wide areas.
Step 2
Shortwave (SW)
Answer
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Typical Carrier Frequency: Shortwave links operate within the frequency range of approximately 3 MHz to 30 MHz.
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Signal Travel Explanation: Shortwave signals can be reflected off the ionosphere, enabling them to reach distant receivers even when they are not in the direct line of sight.
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Typical Use: A common use of shortwave is for radio communication, particularly in long-distance broadcasting and maritime communications.
Step 3
Microwave
Answer
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Typical Carrier Frequency: Microwave links utilize frequencies in the range of about 100 GHz to 2 GHz.
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Signal Travel Explanation: Microwave communication generally requires a clear line of sight due to the high frequencies involved. The signal travels in direct paths from the transmitter to the receiver, which is why towers are often used to relay signals over distances.
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Typical Use: Microwaves are widely used for satellite communication, as well as for ground-based systems such as point-to-point links between buildings.