| 摘要 |
The AM signal from a microphone is converted into an inaudible, FM signal which is combined with the AM signal to form a composite signal. The composite signal is amplified and converted into sound waves by a speaker. Any sound returning to the microphone from the speaker has an FM component and the FM component is demodulated to reconstruct the original AM sound. The reconstructed AM signal is subtracted from the signal from the microphone, thereby removing the echo and cancelling feedback.
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