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Download Review knowledge of AC State the difference between
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Transcript
23 May 2017 6.9 How radio works What is this image? What other information can you get from it? Aims • Review knowledge of AC • State the difference between AM and FM • Describe how a simple radio works Sending sounds by radio RF carrier Modulated RF carrier RF Oscillator Modulator Amplifier AF signal Microphone Sending sounds by radio AF signal Modulated RF carrier Amplifier demodulator Loudspeaker Tuning circuit Radio gaga • AF signal: varying voltage • RF oscillator creates high frequency AC, this is the carrier • AF signals modulate the RF waves • RF wave is then amplified • RF waves then generate a voltage in the aerial • The tuning circuit decides which frequency of RF carrier to detect • The demodulator then removes the carrier wave leaving on AF • This is amplified and then converted to sound AM and FM • This is amplitude modulation or AM • You can also use frequency modulation (FM) • FM has less noise so this is better
