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Figure 4 shows a block (subsystem) diagram for a radio communication system - AQA - A-Level Physics - Question 3 - 2018 - Paper 8
Question 3
Figure 4 shows a block (subsystem) diagram for a radio communication system. Figure 4 information input (eg voice) → input transducer → modulator → amplifier → tra... show full transcript
Worked Solution & Example Answer:Figure 4 shows a block (subsystem) diagram for a radio communication system - AQA - A-Level Physics - Question 3 - 2018 - Paper 8
Step 1
Step 2
Step 3
Explain why the signal strength at stage D is weak.
Answer
The signal strength at stage D is weak due to factors such as:
- Attenuation of the electromagnetic wave across the transmission path.
- A small fraction of the radiated energy reaches the receiver due to distance and any potential obstacles.
- Energy loss caused by reflections from the ground or natural topography, in addition to absorption in the atmosphere.
Step 4
Complete the graph in Figure 5 to represent the combined amplitude modulated (AM) signal.
Answer
The graph should depict the modulating sine wave affecting the amplitude of the radio carrier signal, resulting in a varying amplitude signal that combines both waveforms, creating an envelope that follows the shape of the modulating signal.
Step 5
Suggest whether all these stations can broadcast hi-fi music using the full audio frequency of 20 kHz.
Answer
Not all stations can broadcast hi-fi music using the full audio frequency of 20 kHz. The typical bandwidth allocated for AM broadcasting is limited, generally around 10 kHz per station, which is insufficient for full fidelity audio. The 20 kHz frequency range exceeds this limit, therefore, these stations cannot squeeze the complete hi-fi music bandwidth within their designated frequencies without interference.