| 摘要 |
The invention provides an echo-cancelling system for an optical microphone, for eliminating acoustical echoes from a source of acoustical signals to which the microphone is connected, the system including a source of light for illuminating the acoustical membrane; a photodetector for receiving light reflected from the membrane and for producing output signals; means for supplying power to the source of light; a preamplifier for amplifying the output signals; an input terminal for receiving electrical signals from the source of acoustical signals; a time delay circuit for receiving signals from the source of acoustical signals, and a circuit for regulating the amplitude of the delayed electrical signals, connected between the delay circuit and the source of light, for changing the current supplied to the source of light by the light source power means.
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