| 摘要 |
A circuit for noise reduction is disclosed, including a first signal path connected to receive an input signal and including a high pass filter for providing substantial de-emphasis of the lower frequency components of the input signal relative to the higher frequency components thereof and a variable gain amplifier for amplifying the output of the high pass filter with controllable gain. A second signal path is connected to receive the input signal and provides little or no de-emphasis of the higher frequency components relative to the lower frequency components of the input signal. The outputs of the first and second signal paths are summed to produce a noise-reduced output signal. The gain of the variable gain amplifier is controlled so as to exhibit higher gain when the input signal level is relatively low and to exhibit lower gain when the input signal level is relatively high. This circuit can be used for level-compression, as in a noise-reducing encodier for a signal recorder, and may be used for signal expansion as in a noise-reducing decoder for a signal reproducer.
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